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MG MGB Technical - heater mods

its winter again and I've got the blues with the heater!! I've done all the checks but it's still not hot enough. Has any one done any real improvements like replace the matrix with a sieera one or such like. At my age and as a daily driver I want it to kick out as much heat as a modern one, so have any of you guys done something similar with great results?

gary
G Roberts

For the dead of winter, I usually replace my 180 degree thermostat for a 195 degree thermostat.

I have an "uprated" heater matrix, and frankly it still just produces tepid air. I think the fault is in the valve. I've taken this valve apart and packed small washers behind the e-clip to open the diaphragm as far as possible. (Thanks to Bob Munchausen.) I think the e-clip may have broken because, as I said, the air that comes out is once again only warm.

Another side of the equation is how well are you retaining the produced heat? Do you have any cold air leaking into the cabin? Do you have one of those magnetic flaps to cover up the fresh air intake on the front cowl? Is your hood a nice tight fit over the windows and around the rear cowl?

I've considered stuffing a sheet of foam rubber under the hood to reduce heat loss through the vinyl. If cut to the right size, it would tuck into the front rail, ride over each bow and stop just at the rearmost bow, right above the rear window.

Hope this helps,

Matt K.
Matt Kulka

I too bought an uprated matrix, and can't say I would rave about it. The biggest gain came from the heater valve modification. http://www.mgb.bc.ca/service/heater-valve.html. Very easy and free. I think I used a small nut instead of the washers because so much adjustment was needed to get full flow.
Steve Postins

From others reports the uprated matrix that *is* available for the MGB is a waste of time, can't recall much by way of comments for the uprated blower except there are two types. Out of my standard system I get 140F/60C coming out the heater and that is with an ambient of about 50F/10C. Even with the roof down it burns my feet, with it up, and in the GT (albeit a V8), it always needs turning down after a few miles. It will never give as much air flow as a modern car but should give sufficient heat ... but maybe I'm just hard having driven only MGBs in all weathers including the roadster in snow with the hood down 'cos the sun was shining. If there *are* other problems in the system you could well be wasting time and money replacing bits. But then again, if the existing matrix is blocked, and you replace it with an uprated or completely different item, then I could quite understand you exclaiming how good it was.
Paul Hunt

Over the years, your heater matrix can clog. This might be part of your problem. Another thought: Years ago, I took a trip up north around Christmas in my three year old B. By the time I got up to Arkansas, the car was freezing cold inside--engine temp barely at 140 degrees--heater output negligible. We covered the oil cooler and eventually part of the radiator with duct tape and cardboard to get the temp up around 180. Doing that and sealing the top real well with more of that magic substance, we managed to stay warm to our destination. The MGA used to offer a curtain that could be controlled from the cockpit that did the same thing to the radiator. Might be worth looking into for those of you who live in frigid climes.
R. L Carleen

I put a piece of cardboard in front of the radiator , about 6" x 9" and that seems to allow the thermostat to gain control .
S Best

This really should not be seen as normal. This is my second MGB and initially, due to negligence/ineptitude of the previous owner there are some basic steps that must be taken.

First, as others have already mentioned,check for debris in the air well.

take out the apparatus for the "demisting tubes", at the same time checking the corrugated vent pipes for debris. With the mist tubes out and a drop light, inspect to see if there are any obstructions.
ON BOTH MY CARS, there are 2 felt strips that were originally glued to the control flap..mine were both loose and laying on the "demisting tubes", effectively obstructing the flow.

I checked the operation of the flaps closely, and have found them to be quite superfluous indeed..the flaps close/seal completely when actuated to divert flow in the defrost mode.

...and finally, are your door flaps even open?..there are 2, drivers and passengers.



In summation, once the above steps were taken, I have always found the MGB heater system to be so effective, that I find myself turning it off shortly after..even in the defrost mode.
jegawatt

I thought that I should make clear that I eliminated the felts (2), for the flap..not needed, and why risk them comming off again?
jegawatt

I have fitted an uprated blower (costello fan?) not more heat, but more circulation of air for demisting.
Regards.
http://membres.lycos.fr/mgcontact/fileupload/uploads/costellofan.jpg
michel

Of course it is not the effect *on the radiator* of blocking it that allows an engine to get fully up to temp in very low ambient coditions, but how it prevents very cold air from flowing around the block, and through the oil cooler on CB cars. The surface cooling of the block and sump, the oil cooler, and the use of the heater can stop the coolant getting hot enough to even start opening the thermostat. Under these conditions the radiator will be cool anyway.
Paul Hunt

I have heard that removing the chrome fine mesh grille that you can buy as an aftermarket accessory has helped . I have never seen the need to fit one.
S Best

I've gone to the effort of removing the heater and resealing the box and passages so that every breath the little fan puts out goes through the matrix and into the car just where it ought to. A lot of work, improved it some, but not enough. Most cars I've owned (even older ones) have been able to clear a frozen windshield relatively quickly, and eventually heat hot enough to roll the window down if wanted, even in sub freezing temps. My B is barely able to clear the moisture off the windshield after 10 minutes of running, and that's in 40 degree weather. What happens when it's 20 below?! There's enough heat in the air (its quite hot when you put your hand at the vent)but not enough air. I was thinking of finding a much faster rpm motor and using the same fan, or modifying the heater box to mount a fan/motor assembly from a different vehicle. From what I've seen of the size of other heater cores, the B one ought to be performing well (once the valve is working and the thermostat is hot enough), I think the most improvement is to be gained by increasing airflow. I've read archives where people try TR7 fan/motor, and "costello" fans which are I guess no longer available, but these only give modest improvement. I haven't seen or heard that anyone has come across an easily copied solution to be used by those of us with cold winters.
Greg
Greg

The following site details an upgrade.
I used it to see what was involved in the removal..I am currently doing a heater box restoration.

http://www.chicagolandmgclub.com/photos/b_heater/
jegawatt

Here's what I can't figure out. For a few short months in the fall of 2002 and winter of 2003 I owned a '71 midget. I loved the little beast but alas it was the one MG model I've owned that my wife could not abide - so I sold it. But in the coldest weather - around 20 degrees F, the heater would absolutely drive me out of the car. The air was just plain HOT. I've owned and driven many MGBs over the past 20 years and none of them would come even close. Of course the cabin volume of the Midget is much smaller, but so is the engine.

One factor that I believe we're dealing with is that the 1800 B block is a very cool running engine. A 190 degree thermostat helps, but in subfreezing temperatures, I have completely covered the radiator and the oil cooler; the engine would still run cool, and heater output would still be nil.

For those who think the heater control valve is at fault, I have built a heater control valve as per Bob Munchausen, with only marginal improvement. The major advantage of this design is that it turns on and off much better than the original design. It appears to me that it does open more, but that doesn't seem to translate into much more heat.

There certainly is a problem with the effectiveness of the fan, but the harder you blow lukewarm air, the cooler it feels. So I think the first issue is to route more heat into the matrix. That is, if there is any heat to route.

Allen
Allen

Try wrapping the exhaust manifold with that stuff they sell to keep the engine bay temperature down. Didn't seem to do much for performance, but made the engine run hot enough to blow the head gasket - twice!

I rebuilt my heater following the instructions in the Lindsay Porter book. I did nothing special, just de-scaled the the matrix with Oz (stuff for kettles). Also replaced the pipe that runs along the top of the rocker box as it was very scaled. Heater burns my legs!

Neil
Neil Lock

Ah, the onset of winter! It always brings cries for assistance from those with bad heaters. OK, try this-
One of the tasks that most MGB owners eventually confront is the overhauling of the heater box. The heating system on the MGB may be an antiquated design, but it is adequate if kept in good operating condition. Unfortunately, reconditioning the system is a time-consuming task, so they are almost always in a state of severe neglect. It is not unusual for the heater core to be so loaded with sediment that it barely functions, if at all. Reversing the flow within the closed system by switching the hoses in an attempt to purge the heater core is a very bad idea as it would force the sediment trapped in the heater core into the rest of the system, there to do all kinds of mischief in the coolant passages of the engine, coolant pump, radiator, thermostat, and heater valve. However, you can backflush the heater core with the hose disconnected and hope for the best. Simply pouring a descaler into the system can be risky as it is often the "kiss of death" for an internally corroded old heater core, resulting in leakage into the cockpit. If you want to get its performance up to what its designers intended it to be, you'll have to pull the heater box and do a rebuild. While you're going through this ordeal, keep telling yourself that the entire process is just part of the initiation ritual into the ranks of an elite group of MG owners who have "been there, done that". Consider it to be the MG owner's equivalent of a quaint and colorful puberty rite.
Removal of the heater box is not as difficult as some make it out to be. First, disconnect the battery, then disconnect the wires from the fan at their snap-connecters. Next, remove the three screws that secure the blower motor mounting plate and remove the motor along with its mounting plate. This will make the heater box lighter and thus easier to handle. Now, drain the system and remove the hoses from the heater box. Next, depending on which you have, remove either the radio speaker box or the console and loosen the demister tube retaining clip screws. Remove the screen demister duct tubing and pipe elbows from the lower part of the heater unit, then remove the pipes onto which they were mounted. They should slide right out.
Next, remove the heater air control from the dashboard and disconnect the control cable from it. Finally, remove the screws that secure the heater box to the bulkhead. Pull the cable out with the box. Make sure that you thread the directional control cable through behind the dash - this has two purposes: firstly, so it won't snag on any wires as you pull the heater out and thus result in a electrical problems and, secondly, since it will come out with the heater, it's easier for the cable to thread through the bodywork without having to "U-turn" itself from where the control knob is located. Be aware that there is a rubber gasket beneath the flange of the heater unit and that it will often be difficult to remove. Normally it's just a matter of wiggling, tilting the assembly forward from the top, and just gradually working it out.
Once you have the heater box out of the car, remove the four cover retaining clips and peer inside. If the air intake is not protected by a screen sandwiched between the heater box and the circular air intake gasket you should not be surprised to find a considerable quantity of leaves and other debris clogging the fins of the heater core, thus preventing adequate air circulation. Take the heater core to a local radiator shop and have it boiled out to remove the usual accumulation of crud from inside of it and have them pressure-test it. If it leaks, a new one is available from Victoria British. To do a proper rebuild on the heater box, you will need the following parts:
Heater Unit Base Gasket (Moss Motors Part# 282-750)
Vent Door Seal (Moss Motors Part# 363-145)
Heater Core Foam Seal (Victoria British Part# 9-9079)
Air Intake Seal (Victoria British Part# 12-5556)
Air Intake Screen (Victoria British Part# 12-085)
Heater Outlet Seal (Moss Motors Part# 363-135)
In addition, you will need thick strips of felt which you should be able to obtain from a fabric shop.
When reassembling, pay special attention to the careful sealing of the heater box, so that airflow has to travel through the heater core rather than bypass it.
Now you are ready to reinstall the heater box. Attach the air control cable to the heater box, then attach the block seal, air inlet seal, and perimeter seal to the heater with rubber contact cement. Pass an 8" length of small metal tube (probably a length of steel fuel line) through the rubber grommet in the firewall and up through the rectangular hole where the heater resides. This tube can act as a cable guide for the control cable so that it won't get kinked as you lower the heater into place. You might consider taping a shop rag over the rear edge of the bonnet aperture so the heater box would not scratch the paint as you lower it into place. Using Wire Pull Lube (either Rotanium or Yellow 77 should work fine), smear it all over the rubber block seal. This material will evaporate over time and, unlike grease, will not attack the rubber. Pass the control cable through the metal tube, then slowly lower the heater box into position. With the wire lube, steady firm pressure is all that it should take to get it into place. If possible, have a friend pull the cable and tube from the inside of the car as you lower the heater into place. Once the unit is in place, just pull the metal tube off the cable. Reinstall the fan with its motor and be careful that you do not accidentally reverse the connections.
Should you still be dissatisfied with the performance of the heater, you might consider installing the uprated heater core available from the MG Owner's Club in the UK and modifying the heater valve in the manner described by Bob Munchenhausen in his website article found at http://members.aol.com/bobmunch/index1.html
If you find evidence that water is seeping into the cockpit from under the dashboard, this means that the drain tube for the air intake plenum is clogged with debris. This can be very bad as the water just sits in there in the plenum and can cause rust. Left uncorrected, water will stand in the air intake plenum and the resultant rust can do serious damage. However, it's not hard to clear out the drain tube.
If the car is on axle stands you could slide right under there and see the drain tube hanging down beside the right front of the transmission. It should be hanging down just below the bottom of the car. On the end of it is a round bulb with a slit-like lip. In MG lore this is called "Tom's knob," supposedly after the engineer that designed it. Supposedly this "knob" was to prevent exhaust gases from working their way up the tube, into the air intake, and from there into the heater box, poisoning the air inside the cockpit. Unfortunately, the bulb can eventually get plugged up with debris, usually a compound of teeny bits of leaves and dust. This part is no longer available, so you're going to have to be careful with it.
Remove the cover and look in the corner. You'll find a small hole which connects to the drain tube on the left side of the plenum chamber when viewed from the front of the car. You'll want to avoid damaging the paint, so gently push a doubled-over electrical wire into the hole and gently twist it to clear the hole out, then add water and gently push it down through the tube while twisting the wire. Get under the car, squeeze the knob so that the slit opens, and have a partner flush water under pressure directly down the hole in the plenum chamber. This is the easiest approach and sometimes doesn't work. If it does work, you'll get a nasty bunch of crud on yourself.
If that method doesn't work, there's another that will: The drain nipple for the air intake plenum is located on the right hand side of the transmission tunnel, under the heater and just above the bellhousing. The drain tube is fitted to it's outlet tube by a hose clamp and is accessible from the side of the gearbox tunnel down in the right hand footwell area. You might have to remove the center console heater control mounting or try looking behind the hot air outlet in the footwell. It is pretty hard to see and even harder to get your hand thru to refit. Be prepared for grazed knuckles. Remove the 4 screws holding the flap to the tunnel, then you will see the tube that drains the air intake plenum. It has a clip holding the tube to the drain nipple. Undo that and reach under the car to pull out the tube. Now cleaning out the tube itself is easy. This is really the best way of cleaning the tube as sometimes there's a bend in the tube, thus it cannot be cleaned out using a wire.
I went through this joyous ritual with my second wife's car and resolved to never endure it again. I fabricated a screen using black stainless steel window screen and put it under the chromed intake grill. Nowadays you can buy one from Victoria British for $9.95 (Part# 12-017).









Steve S.

This topic is discussed in Roger williams second book 'How to Improve MGB, MGC and MGBV8'. Roger suggests that the small pipes leading to the heater matrix are the root of the problem. These 0.375" dia pipes are smaller than later cars such as MGRV8 or late Minis, Marinas and Princesses, which use 0.5" dia pipes.

It must be possible to recore the heater matrix and fit 0.5" metal pipes. I had a quote from a local radiator specialist of about £50.00 for such work. Some Marinas used B-series engines so would seem to be candidates for control valve donors and block adapters. I don't yet know how to complete the circuit as far as the return line is concerned. Any ideas would be welcome.

Steve S's comprehensive instruction procedure for removal of the heater box assembly only goes to show what an appalling design the thing is. It combines two functions - those of water-to-hot-air-conversion and hot air distribution. If the existing heater box were cut along the front lower edge, the heater radiator could then be removed and serviced, leaving the hot air distribution system untouched. I seem to remember an MGOC article suggesting this mod a few years ago but I have not tried it yet.

Just my two-pennyworth. Hope it helps.

Peter
P L Hills

Gents,
I have a new website, http://www.s95408591.onlinehome.us/ , which incorporates both my Alternator conversion info AND my Heater Valves info ~ both for slightly modifying the OE heater valve as per Matt's experience, and also offering a homebrew alternative, which frankly, seems at least to be as effective as the OE valve and less leakage and trouble prone.
Bob Muenchausen

Bob-
Thanks for posting your website's URL. I've changed the old one in the article.
Steve S.

folks

Thanks for all your comments, there is just one more thing, I'm getting a decent flow of water through the matrix but am unclear whether or not this indicates the passage ways are all clear or not, or is the flow is just taking the easiest route. What do you think?

Gary
G Roberts

I once installed a Oldsmobile heater blower motor in my '59 Sprite. And I drove it all winter's long. Packed rags, and cardboard and whatever to close the gaps in the top and side curtains. I made it!
Safety Fast
Dwight
Dwight McCullough

Thanks for including my info in your article, Steve - it is much appreciated.

Also, anyone trying to get the most out of the heater system ought to check out Paul Hunt's comments as well at his site, http://www.mgb-stuff.org.uk/wn_heaterframe.htm .
Bob Muenchausen

I upgraded the heater core (matrix?) on my 77 B, and can not say that there was a noticable change. I plan to order the upgraded motor and fan in the future.
R Hill

a relay (see the Moss U.S. site...www.mossmotors.com...tech tips...cranks up the volume...that along with restoring the heater per Steve S. has me turning heater blower off frequently. When doing so I blasted and painted the box and when reinstalling the core into the box got some dense foam at the home repair/hardware store that is used to seal around airconditioners , etc. in homes to seal around the core and force the air flow through the core instead of around. Also found grommets at the same store that fit perfectly around the inlet outlet tubes and really seal it so air goes where intendend. Oh....can't remember if Steve said to clean or have cleaned the electric motor. Brushes are NA but mine worked a lot better by just cleaning it out.



J.T. Bamford

"I plan to order the upgraded motor and fan in the future"

And again not see a noticeable change? A triumph of optimism over experience :o)

A relay *will* increase fan speed, but unless there are problems in the fusebox, switch and connectors which should be dealt with instead, will be negligible. And don't even *think* of fitting a relay for the slow speed of a two-speed motor :o)
Paul Hunt

If you need to replace brushes in the heater motor (or other small electrical motor), you can probably find an acceptable or adaptable substitute among the many replacements offered for power tools and other small motors (appliances, etc). A better hardware store, tool supply, or an electrical motor shop can probably help you find some brush that is either identical or at least close enough.
Bob Muenchausen

Doh! And you could also check for usable brushes at your friendly auto parts store. (gee, that was too obvious! ;-) )
Bob Muenchausen

Kenlowe Fans, engine cooling type, brushes fit old BMC heater motors, and still availible!
I fitted blue Costello fan, useless, like standing on Baker Street underground station, you know, all wind and noise but no heat!! I found the best to gain heat in cabin was to convert to V8 engine, perhaps a little extreme.
Richard Evans

I know an MGB cannot be compared with a Volkswagen Beetle in terms of airtight-ness but cracking a window or 1/4-light open a bit really helps the standard system do its job, in screen clearing at least. Otherwise it is like the fan is trying to blow up a ballon.
Paul Hunt

Hi fellow frozen owners.

I've had it with the existing contraption. Done all the good stuff to my GT, insulated the cabin, firewall
and done all mechanics. Even installed a nice(powerful) fan motor from SAAB.

I can assure you all seals are in place and kosher...even found N.O.S. core, clean as a whistle. I re-routed full 1/2"piping and put a bronze and stainless Marine ball valve in. (getting rid of that leak-prone piece of zinc that hovers over the distributer)

The result? Like an athsmatic mouse breathing its last shallow breaths on my ankle. (Ignition is safe now though).

The temp here is well below freezing and driving has lost its sense of fun.......I'm ready to explore alternatives.

Since our 'B's are one of 500,000 or so, I don't trouble too much about factory 'original' It's not a Bugatti and although the basic car is excellent, a lot of the finishing bits and accessories are damned lame. Built to a price under poor economic conditions, it's as L.G.K.Setright wrote in the '30's "MG makes a very good 'bad car'."

Onwards, I'm going to remove the poor thing and bury it in an unmarked grave (dumpster). That will leave a lot of room to fit a 'Real heater' dont you think?

Now the flaps & gizzies that direct the imaginary flow are pretty sound, not to mention an integral part of the Enever designed box section that holds everything together so well. I'm restricting my mods to the engine bay.

Who among you are willing to explore alternatives that
A) Work, B) provide real comfort, and C)look good and professional?

I'm on the case, join me, puleeze!!!! I'm freezing
and 'Alice', my 67 GT has always been my main, often only car.

I will post my findings, I invite you to join me and post too.
Stewart
stewart caskie

Many years ago I purchased an old Chevy to use as an airport using airport transfers tunbridge wells car and installed an electric heater. Toasty.
Dan Robinson

Stewart,

So you're from Ashville. We were just down in Maggie Valley last week. Check out the "Wheels Through Time" Museum in Maggie Valley sometime, if you haven't already. It was worth the trip.

Now, back to the topic. I'm with you, Stewart. Here in Craig County Virginia, we're at 3000 feet altitude and it does get cold. My Midget used to get toasty - downright hot - in this weather. I too built a ball-valve to replace the distributor sprinkling system in my GT. The main improvement is that it works: when you turn it off, it turns off; when you turn it on, it turns on. But it doesn't turn on very much.

In terms of actual heat, I'm tempted to try a diverter type valve that progressively routes the coolant to the heater core INSTEAD of the radiator. Does one gain much by covering the oil cooler? ' Confess I haven't tried that. Last year, when temperatures dropped below 20 degrees F, I covered the entire radiator with cardboard, with little or no effect. When the weather turned warm again I forgot to uncover the radiator promptly because it didn't make any difference. The temp needle stayed in the usual place.

But Stewart, I'm not sure I agree with you about the air movement "flaps and gizzies" that direct the imaginary air flow. Don't most modern systems use "puller" fans downstream from the heater and A/C cores? I tried A/C
in my MG Magnette a couple of years ago and among my failures, using the existing air "movement" system figured largely.

I'm wondering if the heater hose tap off the head serves the heater well, even with a more free-flowing valve. I'm tempted to blank off the outlet from the head and attempt a heater tap from the thermostat housing. If the maximum heat is generated in the head, the coolant leaving the head at the thermostat ought to be hotter than that leaving between #4 and #3. Further, I'm thinking of an electrically powered impeller in the line from the thermostat housing to the heater, "encouraging" hot coolant to go to the heater rather than the header tank. Once I get the heater core hot enough, I'm thinking of pancakes fans at enlarged floor outlets which will supplement the air movement attempted by the original fan.

' Hope this thread reveals many more and better ideas.
We need 'em!

Cheers - Allen
Allen Bachelder

Hey Allen,

Nice addition!
30-some years ago I lived in Aberdeen and drove my '37 TA around all year...including Germany, Holland etc in winter.
I fitted a nice little Bedford truck heater from the scrapper's and plumbed it into the head. Lord, was that fine! I zipped up 1/2 the tonneau cover, used a blanket and drove one hand out-one hand under, swapping every-so-often. It was wonderful being warm in that old 'rickshaw'.

What's your GT like?

Anyway, JC Whitney sells a self contained unit that might be made to fit handsomely. There's pics, but they don't show the back 'motor' side and it seems that is a 9" motor sticking out of a 4" case. I'm asking for drawings.

I had an MGA and seem to remember a separate fan, ducted to the heater plenum....that's an OK way too!

I'd rather have one 'honker' than a gaggle of pancakes fans. Oh, lest I forget, do blank off your oil cooler and make a panel to fit your rad with a 9" hole for the fan, flattened down at the top by 3" or so to keep the upper rad uncooled (convection/thermo-syphon) and near the header tank. We're keeping BTU's here. Worked on the TA.

Stewart.
stewart

I carefully cleaned and repaired my heater core (a tube had broken off). I painted it then tested it and it is now perfect. I then find on closer inspection that the heater box is rusted too much to be used!

So until I find a replacement I won't run a heater in the car. I guess it is a good idea to fit two blanking plates in the engine bay to stop fumes getting into the cockpit? One over the round hole on the vertical panel and one flat over the top of the flat bulkhead.

Simon
Simon Jansen

I read all of your comments on the B heater problem. I have owned and driven MGB's and C's for 30+ years and my wife and I still use them as every day drivers. The winters are rather mild here in East Tenn, but sometimes in late Dec and thru Jan it gets downright chilly. I simply install a blanking plate under my fresh air grille and open up the fresh air vent behind the radio. This acts as recirculating air and instead of fresh cold air blowing over the heater core that is trying to heat up, it is warm air blowing over that heater core. It gets quite comfortable and if the windows try to fog, I simply open the vent windows if need be. It is that comfortable. When the temps get and stay below 30 degrees, I simply block off the radiator with a piece of water resistant cardboard with a hole cut out, appx 8x10 or so. Moss and VB sell a black magnetic cover with the MG logo that lays over the grille if you don't want to make your own blanking plate.
M. Whitt

Allen,
As per your question about covering the oil cooler core. I do it every winter. But not for raising the coolant temp and heater efficacy, but to keep oil pressure up.

Sounds weird, I know, but apparently, from what I read, modern oils are formulated such that as long as the oil stays cold, it will assume a thin consistency so as to move more freely to where it is needed, albeit, at reduced viscosity and reduced protection. However, once the temp is raised under normal driving conditions, it supposedly thickens making it much more able to protect bearings etc.

If the oil cooler is left exposed in very low temp conditions, such as can happen here in Idaho, my oil pressure gauge will show a Max. oil pressure of about 40-50 PSI. However, if I place a plastic shroud over the oil cooler during winter to keep out the artic air, the oil pressure will rise up to its normal level of about 70 PSI.

In both exposed and unexposed conditions, water temp will go up to normal (about 190 F), but the oil pressure seems definitely affected by the cooling effected by the oil cooler, in spite of coolant temp. If there is a Petroleum Engineer among you, is my situation typical for an oil such as Castrol GTX 20w-50???
Bob Muenchausen

M Whit,
What a simple little tip and so effective. I'll be using that one to keep the interior a bit warmer.

Thanks, Charlie.
Charles Goozee

You are very welcome Charlie. And I agree to what Bob said from Idaho. Blanking off the oil cooler is a great idea on the cars too. I do that on my oil cooler cars too.

Mark
M. Whitt

I just park up in a layby with the girlfriend, before we know it the windows are steamed up and things get really hot! Heaters fine. Back aches a bit though.

John Thomas
John

Thanks guys, for your suggestions. Here in the Appalachian Mountains, at our altitude, we usually have 3-6 weeks where the morning temperatures are always below freezing - usually around 25 degrees F. I'm guessing this is around -4 C. Occasionally it will drop to 5-6 degrees F. Last year, I covered the air intake grill with one of those magnetic covers. Another way to get it to recirculate is to open the fresh air vents in the dash. When the fan is running with the outside grill covered, a sheet of paper held up to the dash vents will be sucked toward the vent and "stick" to it - demonstrating the vacuum, confirming that the idea is working. In cold weather, this does pose a problem for defrosting, but then there isn't much to lose anyway. One does need to keep vent windows cracked open. In conjunction with this, I covered the radiator completely while watching the gauge, expecting it to overheat. Surprise, the gauge didn't read any differently at all. Nor did it affect the amount of heat coming from the heater.

Bob, thanks for explaining something I've noticed for several years. When my car is very cold, the oil pressure will hang just below 50# until the engine starts to warm up. Guess this is why the engine still cranks fairly easily at 20 degrees F even with Castrol 20-50 in the sump. I will promptly cover the oil cooler!

I don't expect covering the oil cooler to make much difference in heater performance though. I've had the same heater problems in MGBs without oil coolers.

But perhaps all these suggestions employed at once will make some difference. - Allen
Allen Bachelder

Forgive me if I am repeating anyone elses comments...Has anyone considered whether the engine thermostat is working correctly?

The temperature of water into your heater matrix is one of the variables that affects its operation the most.

If the thermostat is too far open the water flow through the heater will be less. In addition the temperature of the water will be low.

I once diagnosed a faulty thermostat using a digital contact thermometer with probe taped to the rubber outlet hose. When I pulled out onto an arterial road (speed 80km/h) I watched the coolant temperature plumet from around 70degC (low) to around 40degC (previously I thought impossible!) and that was on a 25degC day!

In the aircon industry a 5degC rise (say from 80degC to 85degC) in heating water temperature can give a large increase in heating capacity given a constant flow of water. If the heater matrix/coil is designed to operate with the temperature of the coolant at the thermostat rating and you then put 40-60degC water through it don't expect to get any heating performance out of it.

Renewing you thermostat may solve the problem!

Regards,

Dom

Dom

For anyone driving a 75up mg here's another way if your daring enough and good enough at welding. run a .5 diameter pipe through the collector flange on your after market exhuast systems to heat up your heater water supply alot more then what the engine would normally do. (Basically cut a hole through your exhuast pipe, run the tubing through (use a thick guage tubing btw!) weld it in place and make sure its sealed then run your heater hoses. This can also work for other mg models either running the piping through the exhuast system or wrapping it around the exhuast system there by using the exhuast as a secondary heater element. You must make sure to use thick guage tubing usually a 1/16" inner wall tubing will work and be absolutely careful not to burn through the pipe when your welding it, last thang you want is to risk blowing your heater up or your engine or radiator by introducing hot exhuast gases inside it.
Where did i find out about this you might be wondering? Well it was surprisingly enough on modern marvels a few cars in the 30's 40's used the exhuast system to heat up the supply water to the heater core. It didn't hang around long after the V8 came out.
CJD Dark

Dwight,
Do you recall what model Olds you got the fan from? I need to replace my trashed fan motor and will probably get a substitute from the local junkyard. I just wanted to know where to start looking.
Bill
Bill Boorse

Bill
It was an older model that I got out of a '66 model 88, I think.
But models from the 70-80's should be the same.
It just ran so much faster, that it 'caught' more heat.

Hey!
Her's another trick that I used successfully in many of my cars.
Throw away the belt driven fan!
And in sub-zero weather, I even completely covered the radiator.
[with cardboard] It's called a 'Polish thermostat.
[I apologize to my Polish friends.]

Just watch the temperature gauge.
I think that an electric cooling fan is far superior anyway. H.P. & economy gains, plus faster warm-up.

The trick is to get as much heat as possible into the heater core/matrix.
Safety Fast
Dwight
Dwight McCullough

I was wondering about the heating on my 73 B. It was working but I had remembered it working much better years ago, when I got stuck in a Blizzard hours away from the nearest gas station. (When the car isn't moving, it's a toasty little device)

The radiator had recently been flushed, so i didn't think that was it.
I took apart the blower and oiled bearings, cleaned it, etc. Putting it back together, I noticed that the two nuts on the back of the blower directly affect the speed of the fan. If they're too tight, the fan won't blow or only blow very slowly. With the fan blowing, I could tighten them to the optimum level.

This simple adjustment made a whole lot of difference in terms of cabin heat
Philip

In my '67 GT there are flaps to turn off the air to the footwells. The valve to redirect the air for defrosting can be removed from the airbox, which enhances the air flow. For windshield defrost, close the footwell flaps. Without that cranky sticky baffle in the way, the air flow volume increases and the problem rotary control is no longer needed. I'm running an 11 lbs radiator cap and a 195 thermostat year around. Heat even on cold days isn't a problem.
Barry
Barry Parkinson

Dom,

Thanks for your post. You're absolutely right in that a check of the thermostat ought to be item #1 in the quest for better heater performance. In fact, until last summer, my 74.5 GT was running with a 160F (70 C?) stat. I replaced it with a 190F (87 C?) stat and the gauge tells me I'm running much warmer than I was (uncalibrated gauge - it's now up closer to "N" than it was). There is a marginal improvement in heater performance but I'm underwhelmed. Sure, when outside temps are around 50 F (10 C?), sometimes I turn the blower off, but at 25 F (minus 4 C), forget it. Again, my Midget was not like this. At 25 F, the Midget heater would cook you right out of the car unless you cut it back seriously.

I find it hard to believe that an 1800 cc engine can't put out enough heat to keep the interior of an MGB comfortable down to at least 10 F (-12 C). There's a fundamental flaw here that we're not addressing. Or is it a combination of multiple flaws? - Allen
Allen

I count nine areas that can cause the heater to underperform, so after 30 years it is quite possible that it *is* a combination of multiple flaws. Sort out those and there are at least four improvements that can be made, or though two of them - the uprated blower and matrix - don't always get a good press.

My daily driver GT always kept me warm with the heat control not on max even during a two month period of below zero temps night and morning. Admittedly it was a V8, but it was cold enough to freeze the water bottles of many modern cars which could be seen stopped on the hard shoulder night and morning scraping encrusted salt of the screens by hand. My water bottle never froze either.

Both my roadster and V8 put out about 140F/60C with an ambient of 50F/10C and that is more than enough for me and the Navigator. But maybe we are just 'ard.
Paul Hunt

Hi All

As a Midgeteer, I can throw in my 0.05 here to point out that Spridgets have a length of 4" diameter trunking to lead air from the front of the car to the heater matrix, which develops a considerable 'ram' effect when the car is in motion. As far as I know B's do not have this ducting.

In the mid-90's I ran a Midget as my daily driver, top down unless there was something falling from the sky. My feet were always toasty warm, and this despite the fact that in all the time I owned the car the heater fan did not work!

Maybe the answer is to sell those big ol' B's and get Midgets...

James
James Reinhardt

James,

I know that there is a more than little truth in that of which you speak. As I've noted before, my Midget (a '71 model 1275) produced super-abundant cabin heat under the coldest of circumstances. Why did I sell the Midge and retain my "big ol' Bs? Because my wife didn't like Midge. It's the only MG she's ever seen that she decided to dislike and I was unable to persuade her otherwise.
B's don't have those 4" ram air intakes because they try to suck their intake air from the grill on the cowl. Perhaps one of us could design an air scoop that would ram the air in the grill...

- Allen
Allen

I block the intake with duct tape and open the fresh air flap to recirculate cabin air. My cheap top fits so poorly that it really doesn't matter.

There is a considerable high pressure point at the front of the windshield (cowl induction scoops take advantage of this effect) so the "B" does, in effect, have ram air.
Interestingly, a study was done on air flow on an MGA once and it was found that the engine vents actually inducted air once the car speed went over something like 25mph.

Mike!
mike!

This thread was discussed between 19/11/2004 and 09/12/2004

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