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MG TD TF 1500 - Stil overheating

My '53 TF ran too hot, 90°C at 90 km/h and started boiling at 100 km/h. I decided to rebuilt the engine, and found that the water gallery feeding the head at the back of the engine was blocked by scale. I supposed that this was a good reason for my problem.
The engine has now been rebuild, descaled, flushed, the head has been tested for cracks and resurfaced (it was not found wrapped by the machine shop), the head gasket installed with jointing compound, the radiator has a new and thicker core, and the problem is still present. I am running in the engine at 3000 rpm and the temperature is still at the 90°C mark with an outside temperature of 15°C. The thermostat is the 74°C model. The water flow in the radiator seems correct. The temperature is measured with an electric thermometer which is accurate. The timing is set at TDC and the centrifugal advance seems to develop normally.

I am running out of ideas, and I place myself to the highest world XPAG engine authorities to find a clue.
JM Thély

JM,
How many miles are on the rebuild ?? A fresh engine might generate a bit more heat while it is "breaking in"... Also, probably not the cause, but check the position of the fan blades.. while it is impossible to install them to push the air away from the motor, it is possible to mount them "Backwards" so as not to be as efficiant as when mounterd properly..

SPW
Steve Wincze

JM

A couple of items. Is timing correct (set by static method)?

There is a small hole in the water gallery behind the top front freeze plug on the carb side of the engine. Did you drill this out?

Bill
Bill L

All of the above dead on, except the small hole deal. Timing- with modern higher octane, even set TDC static too retarded- advance a little. Is the thermostat correct (does it really work- check it)? 50/50 water/coolant? (too much antifreeze doesn't carry heat as well). Read Neil Carnes disertation in a recent Sacred Octagon- he explains in detail what I have long maintained- the block cools by thermosiphon with practically zero active flow through the small hole. The laws of physics cannot be changed- the miniscule amount of flow through the small hole cannot carry any relevant amount of heat! I think most instances of miraculous cooling after drilling it out deal more with removing the 5 pounds of sludge and rust out of the bottom of the block. Just my (and Carnes) opinion! George
George Butz

Steve,
Only 200 km since rebuild. But it is strange to me to find exactly the same temperature that before rebuild.
I have forgotted to say that the car is equiped with an electric blower set to switch on at 95°C.

Bill,
The timing was set by the static method. The dynamic advance goes to its maximum but I have no mean to check if it is correct at every rpm.
For the small holes, I am with George and Neil.

George,
I tried to advance the timing +5° before the rebuild: no change.
The coolant is a ready to use antifreeze which works fine on other cars. I tried tap water: no change.

I am also interested to know what is your normal temperature in such conditions.
JM Thély

I would set the electric blower at 75/80C. Certainly not 95!

Denis
Denis L. Baggi

Denis is correct- 95 way too hot- you are almost boiling by then- and maybe already are in the hot parts (around the exhaust valves/ports) of the head. My TD runs 80-85ish when weather cool, 90ish when really hot or in traffic. Make sure the thermostat is accurate and fully opening. Also, try blocking off the bypass.
George Butz

Just a thought. Are the radiator slats (louvres en Francais?) sufficiently open? Sometimes a careful tweak with a pair of pliers top and bottom of each slat will enable them to be twisted open a tad more resulting in a more direct airflow into the radiator core.
G.E. Love

I am a member, just not logged in.
JM,

Have you checked the distributor. The washer at the bottom of the shaft wears down over time, allowing the shaft to rise. If it rises enough, the distributor will try to advance & retard somewhat at the same time. The most notable symptom is that the operating temperature will steadily rise at speed until it overheats. If there is a lot of play in the shaft, try replacing the washer and it should cure the problem. I have seen this on several cars in my club, even on my TF a few years back.

Ray Pittenger
Ray Pittenger

While I tip my hat to Neil and George I do have to disagree with their position that the hole/holes are of no use in helping cool the engine. Been there, done that - and swear by the results.

http://tinyurl.com/yr4fq

Best part about it it only requires a few hours work, can be done by the owner, costs less than $2 (new core plugs) and even if it doesn't fix it, doesn't hurt it.

Grin - and George, come on - 5 lbs of sludge?

Best,

Gene
Gene Gillam

Ok, so I didn't weigh it, but there was a solid wall of rusty sludge when the bottom core plugs were removed (accumulating for about twenty years). Took a long time to flush and pick out with a coat hanger, and left a huge rusty stain on the cement that wife was not pleased with!
George Butz

My 53 TD drove me almost crazy with overheating until the cooling system was explained to me. Here goes.....the original thermistat had a "sleeve" on it that would allow coolent to circulate only through the small "side" outlet when cold. This was done to assure that the engine would warm up quickly. It allowed about 30% of the radiater to work. When that coolent became hot enough, the thermistat would open and block the side outlet, therby causing the entire rediator to work. In my case, the modern thermistat had no "sleeve". I simply blocked off the side outlet with a plate in which I drilled a 1/16 inch hole to avoid any air pockets. I cut the plate from a beer can with a pair of scissors. I hope this helps. Tom
Thomas McNamara

I fitted an electric fan ( Kenlowe ) to my TD and it always ran hot even boiling. I tried a number of things which included placing a restrictor in the bypass hose to force more water through the rad. It worked to some extent but the conclusion I came to after a long period of trying different remedies was to remove the Kenlowe and refit the original fan blades. The reason for doing this was because I felt that by the time the engine got hot enough for the fan to cut in,the engine was too hot for the fan to do any effective cooling. For me the re-fitting exercise worked and since then runs at a steady 80c and that is with a 9.25 CR head!!

Good luck,

David Tinker. Wales UK
David Tinker

I m a TD guy so overheating is not that bad, but I have a friend here, actually a british chap, who has TF and he had the same problems you mention until I recomended him to have his radiator rebuilt (not cleaned, flushed or similar) but have a new one built using the old tanks and good bye overheating.
The blade in the wrong direction is also a good hint.
Jose Vargas

Just a thought, but perhaps you are running too lean, which will cause hot running. Try enrichening (is that a word?) the mixture. That may help to cool things down a bit.

I do like Jose's radiator idea.

Larry
Larry Thompson

At the moment, I am with David and G.E. Love and will try to refit the fan blades. Then, when the problem is fixed, I will make the Thomas improvement to improve the cooling efficiency.
All the other points which were raised have already been addressed and checked. Many thanks anyway for all your contributions. I will post the results of my experiments.
JM Thély

Guys,

I'm with Gene regarding the hole(s)behind the freeze plugs. Many years ago I helped a friend rebuild his TC engine. The block was clean as a whistle internally because we had it vatted at Chem-Strip. Once the newly rebuilt engine was back in the car we had severe overheatng problems. Of course, we tried all the remedies that have been mentioned plus anything else we could think of - - with no success at all. This went on for weeks and weeks. Very frustrating. Finally someone told my friend about the little hole behind the front freeze plug. We were highly sceptical that such a thing could be a factor, especially since we had had the block chemically cleaned, but, hey, what did we have to lose. Imagine our surprise when, upon removing the freeze plug, we found a small flake of shiny solder stuck in the hole! Where did the solder come from? Well, my friend had had his radiator rebuilt while the engine was out, so we guess it must have come from the radiator. We plucked out that little flake of solder, replaced the freeze plug and - - cool as a cucumber!

To this day I can't understand how one little 3/16 inch hole can make such a difference, but the factory must have thought so too, because about halfway through the xpag production run they added a second hole behind the rear freeze plug. I guess it takes twice as long for the aforementioned sludge to block up TWO holes enough to cause a heatng problem.

Make of it what you will. That's my two cents worth.

Cheers,
Reed Yates
Reed Yates

I suspect that the small hole allows the air to bleed out of the upper end of the cylinder block.
Bill L

Some years ago, I read somewhere that when the subject freeze plugs are removed, one should make sure that there are no pieces of the casting still inside the passage way. I stuck my finger up in there as far as I could and found that, indeed, the passage way was partially blocked. I carefully removed the casting segments with a hammer and punch followed by a long magnet used for retrieving lost steel nuts and bolts. After each hammer strike I probed the passage for the broken segment with the magnet. I revoved quite a few pieces before I was content with the workmanship. The coolant now can flow freely through the passage way. Unfortunately, I cannot claim any improvements since I did this to my spare engine, yet to be installed. Opening these coolant passages are bound to improve the flow.
Jim Merz

This is no cure, but it may help some TF owners.
Undo the rear latch on the bonnet sides and allow the rear corners to pop up. A lot of heat will escape through this 'new louvre'.

Matthew
Matthew Magilton

Gentlemen:
I have been following this saga for days now and please allow me to interject my two cents worth. The TF has a pressurized cooling system. is the cap correct, and is it holding pressure? How about the carbs, too lean? Let's not forget the timing and distributer bushings so the advance works as intended. Everything correct there? I had a problem with my TD and it turned out to be carb mixture and timing with timing being the ultimate fix. I run around 8 degrees advanced and have a five speed trans and a 4.3 rear. I only get hot at extended periods of speed (65mph)but it cools right down as soon as I ease up off the throttle just a bit even on 90 degree days. Lastly, ...got the right head gasket for the motor, I know you said XPAG..we got round or bananna hole heads or gaskets? I suggest using a timing light with a degree meter it's much more accurate than static or guess work. Whatever it happens to be IT'S FIXABLE, I am interested in the outcome.
Roy
Roy Dougherty

JM - Regarding the overheating problem on your TF, all the comments and ideas so far are spot-on from my experience. One final check could be made on the small detachable louvred plate on the side engine panel. Are the louvres in the correct direction to allow air to flow from inside the engine bay area to the outside? Sometimes this can influence the heating problem.
Rob Grantham

Cars will tend to run hot at speed if the exhaust is overly restricted. I recently had a good deal of trouble with a B - cause was mice had filled the exhaust with dog food! Especially likely on cars that are dead in the winter. They will go all the way up the pipe and through any open valves, filling up a cylinder or two with food, nest and mouse pee - hell on parts! I found that out after I took the carbs and head off to get same out of the cylinders that had open intakes.
Happy hunting.
FRM
http://www.usachoice.net/gofanu
FR Millmore

Would it be possible at all to learn mice to decoke the pistons, without taking the cilinderhead off?

Sorry for that, Willem
Willem van der Veer

No, it's a trade union thing. They do no useful work, unless you guarantee unlimited free seat cushions and wiring harnesses for life!
FRM
FR Millmore

And I thought I had trouble , with mud wasps sealing off my lawnmower exhaust!

Matthew.
Matthew Magilton

JM,

If all these suggestions fail, I have two more ideas to give you new hope.
1.) Is the impellor on the water pump in good shape? Possibly the blades/fins/vanes are corroded and the tolerances so poor the pump is inefficient.
2.) Make sure the spacer between the pump pulley and the fan blades is present. The approximate 3.0 cm thickness brings the blades significantly closer to the radiator. Your thicker core will have to allow this.

Bill
Bill Hite

If all the above has been done I would go the radiator rebuild route too. I was in the same position until I had a new core put in. Now I cannot get my car to run above 80, even on very hot days in the mountains.

Chris
Chris Couper

I have listened to this issue about how cleaning out the drain holes behind the frost plugs affect the cooling of the XPAG engine ever since I got my TD. When I rebuilt the engine I closely checked the design of the flow patterns of the coolant through the block and the only reason for these holes that I can see is to completely drain the main flow path to the back of the block. These holes are the only connection between this path and the drain plug. I believe any cooling effects that can be attributed to cleaning out these drain holes is probably the result of carb. tuning changes when the carbs were off to remove the frost plugs.
J.W. Herbert

JM,
I too had a nagging over heat problem . I was tipped off that antifreeze is NOT the best item to transfer heat out of the motor . If you store your car outside in sub freezing weather you may need antifreez other wise why use antifreeze ?
I flushed out all the antifreeze and replaced it with water and a dose of anti rust stuff and a neat item called HOT SPOT . The HOT SPOT is a agent that makes water,,,wetter . It prvents water from making bubbles at the hot spots in your engine ,like near the valve seats , bubbles do not carry heat away.
I live in Philadelphia Pennsylvania USA and trust me it gets hot here . In the summer it often hits 90 to 95 degrees F. Since useing water with HOT Spot and anti rust my car has not overheated once . Think about it do you realy need anti freeze ?
It's a cheap quick easy fix what could be better ?
A.L. Gerstle

This thread was discussed between 13/04/2004 and 16/05/2004

MG TD TF 1500 index

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