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MG MGB Technical - Relocating oil cooler

I have a chrome bumper GT with the oil cooler in front of the radiator.

I want to retain the oil cooler (the engine is used hard) but maybe relocate it away from the radiator so that I get maximum airflow through the radiator (modified engine, runs hot).

Has anybody managed this and, if so, how please?

Thanks,

Neil
Neil22

On the rubber bumper car it is below the radiator duct, and there are holes in the front valance to provide air for it. But why move it? Are you having over-heating problems? If you are I would look for other solutions that the position of the oil cooler. I suspect that you could spend a lot of time relocating the oil cooler to find that it has made no difference to your problem. Even with a tuned engine the standard set up should provide more than enough cooling.
Mike Howlett

Most racers have the oil cooler relocated below the panel in front of the radiator. I would not think you need this for a road car with modern oils
Stan Best

Stan, why the statement, "I would not think you need this for a road car with modern oils"? Are you implying synthetic oils?

The reason I ask is that my '69 B runs hot too. A friend suggested I run a synthetic oil in it, suggesting it'd make it run a bit cooler. Fact or fiction? And if so, a significant difference?

Curt
cjd DeHaven

How hot? If it in't losing coolant or steaming it in't overheating. With a given ambient temperature the higher the coolant temperature goes the more efficient the radiator is, i.e. it is self-regulating. Only if it gets more than mid-way from N to H would I tart to ponder thing, although I've seen my V8 on the edge of the red zone before now and didn't get any problems. Most people would be considering an electric fan or fans, I would have thought. There can also be quite a few reason why an engine is running hotter than it *should* be, and those should be looked at first.

As for synthetic if you mean the very low viscosities they are designed for modern engines with very small bearing clearances and a desire for low running friction i.e. lower emissions. In an MGB, even one with as-new clearances, I'd be bothered that the film wasn't keeping the bearing surfaces apart. I would think the effect on heat output in an MGB would be minimal, if the engine is running normally you would gain nothing except a lighter wallet, and if it is running hotter than it should then the real cause should be sought and fixed.
Paul Hunt 2010

In my case, it'll go way above N if I let it. As long as I had the car it always ran on the hot side.

A PO had the rad re-cored - it even has a serial number tag from my local rad shop. I wonder if the core he used wasn't something less than what was there prior or what it should be. Quite a few years ago I read on this site about alot of folks using a core from Modine. I looked into it a bit at the time but my local shop said he wasn't able to get the Modine product. Never did understand or find out why...

On one particularly hot day the temp went up too far - to the point where one of the bearings on the crank failed. So I rebuilt my first (and only) engine. Later found out I could have had a rebuilt shipped from the UK for less than I spent on it here in the US... While I was at it though, and with my young testosterum-infused attitude I had the cylinders bored 10 over and put in HC pistons. What a duh move... I really regret that today. Funny how we change with age.

I ended up putting an electric fan on it and for the most part it stays down around N. I don't really care for the sound it makes - sounds like siren... But it does work and I only turn it on when I see the temp go above N.

The car's been sitting for the past couple of years and this summer I've started paying attention to it again. I've really enjoyed tinkering with it again and there's a few things higher on the list than the cooling system right now. I would like to take a fresh approach on that sometime, though.

At the end of the day it is what it is and I have what I have. I still love the car and it's one more on the road.

Curt


cjd DeHaven

I've got a three core radiator and thermostatically controlled electric fan. The shroud is complete with the foam strip on the top, the water pump has been changed, the system is clean and unblocked... and yet it boils after a hard run.

When I say a hard run I mean an autotest test, or five laps of a circuit, not a trip to Tesco. It even boiled on the rolling road...

The engine is fine; smooth and powerful - 1860cc, Piper 285, big valve head, Peco, a pair of HS6s, Magnetronic on a new distributor built for the specification, etc, etc. It has always run hot; I use BPR7EV plugs when using it hard - the ceramic on the standard plugs cracks after a while.

So I'm trying to give it all the help I can!

N
Neil22

Neil22-
I relocated my oil cooler position to a new position behind the front valance in order provide unobstructed airflow to the radiator matrix. My 1972 MGB has the vented front valance from the 1972 to 1974 ½ models with a venting duct to the oil cooler provides adequate airflow to the oil cooler. As an additional benefit, this vented front valance (BMC Part # HZA 4812) was originally introduced as an aerodynamic improvement in order to reduce the tendency of the front of the car to “lift” at high speeds. Moss Motors here in the USA can supply this later Chrome Bumper front valance with its two front vent holes. (Moss Motors Part # 457-115) for $169.95. Victoria British can also supply it, Part # 9-918, for $109.95. Our British cousins can get it direct from the manufacturer, British Motor Heritage (Part # HZA592), which can supply the later Chrome Bumper Front Valance with its two vent holes for £68.69.
Stephen Strange

You might try locating it to the side out of the direct line, the extreme right for example. A bit like an MGC.
Just to be a bit different, why not. Won't cost you anything except four drill holes to try it. It probably won't make much difference because the oil cooler is cooling the block, which is thermically connected to the head reasonably well. Heat is being radiated. However if you've got genuine cooling issues because your motor is hotted up, a bigger or more efficient radiator (and electric fan despite the noise).
Like this article
http://www.eaa.org/experimenter/articles/2009-06_radiator.asp
a three pass radiator. The water has to go the long way around, no shortcuts.
Peter Sherman

When the B was designed oils were a lot less capable than they are today. The oil cooler meant that oil pressure always stood up under hard driving back then. The water circuit should do all you need, everything possible you could ask is in the archives here.
Stan Best

Stan, Based on a standard or lightly modified engine. The fuel we have nowadays is completely different from the fuels we had in the sixties, seventies. The present mixture combusts at significantly higher temperatures. Still the balance of the entire system appears to be ok during operation. The problem really commences when idling. My B, a completely overhauled engine with re-cored radiator, new oil cooler with a stage 2 head and the maximum advance at 31 degrees, if I advance further I experience a lot of pinking runs at 85 to 88 dgrees C when the outside temp is 30 degrees C. The coolant temperature, however, starts to climb and climb and my water temperature does not level out at 100 dgrees C. While idling my oilpressure gauge commences to rapidly swing between 40 and 60#.

As it does not level out I do not where it is going so I am not very pleased. I blame the fuel we buy as major contribution to the problem. At this point in time I am considering a run on a rolling road.
Next I am trying a test with bonnet raised at the back to find out whether it is the heat that accumulates under the bonnet.

Could it be that my ignition is too late when idling only?

Look forward to your feedback

Frank



F Navest

The oil gauge jumping between 40 and 60 psi is usually due to air that is trapped in the copper line that runs from the engine to the gauge. This a very common affliction. RAY
rjm RAY

Frank,
overheating only when idleing implies not enough air being moved through the radiator by the fan. Are you idleing too slow?
The easy answer is put an electric fan and adjustable thermostat in. One of the ones with a plastic surround. You won't need a big one. They don't cost much Just zip tie it to the front of the radiator and it will kick in at whatever temperature you set. Like this one, (although there are much cheaper brands around).
http://www.daviescraig.com.au/
In theory you shouldn't be having problems unless your water pump or mechanical thermostat (the one in the top water outlet) was bad. In fact I'd change the thermostat out first, that's very easy and cheap. Get a new one , or if you can be bothered and you've got a thermometer you can test it in a saucepan on your stove.
There were a number of temperature thermostats over the years, but so long as it is fully open at 88 degrees C it's good enough.


The back of the bonnet thing only works when the car is completely stationary. The moment the car starts moving the windscreen area is a high pressure zone. Also without the rubber seal it will let water onto the foot well on rainy days and find ways down onto your socks.

I'm running a V8 and I have the though the guards headers. Because these work so successfully some people will put vents in the inner guards. Much more effective location than bonnet vents as the wheel arches are low pressure zones and suck air out of the engine compartment. You'd have to be running a really high tune, perhaps supercharged 1800 engine. However you really should not need to go to that extreme.

However that's allot of mucking around and the electric fan will fix your problem right now for less than $200.

Peter Sherman

Neil22, I wanted to make a contribution to show that my car is also quite warm and that I have been thinking a long various tracks myself during the past months. I will try a thermotat controlled electric fan for the time being.
Lifting the bonnet or louvring does not seem to be a good idea.
A careful check of the basic settings, like the advance may be worthwhile.
This leaves me and probably you as well, the last option. Have a run on a rolling road. Should you decided so prepare the car as dcescribed in the last chapter of the BOOK by Peter Burgess on MGB engines.
If you go unprepared hyou will be paying a lot for getting all the settings right. Have all your liquid levels including the final drive properly filled.
Valve seting, ignition as well as carburation adjusted.

Frank
F Navest

My car is tuned 1950cc 271 cam Peter Burgess big valve head etc. It used to over heat in traffic, but has been fine since I fitted the Moss fan shroud. This avoids the ugly (IMHO) electic fan and any problems with the electric fan circuit.
Stan Best

Air in the gauge oil line does nothing, 60psi is 60psi whether it is being transmitted through air, oil or anything else. Fluttering of the gauge is well known at certain combinations of oil temperature, revs and pressure, is caused by the pressure relief valve and differs from car to car. The factory added a sintered plug to the gauge to reduce it, but it still happens. Chances are if you changed anything to do with the relief valve it would change, but this may be anything from stopping the fluttering altogether to simply moving it to a different combination of circumstances.

The oil cooler was originally an option, only standard later to stop paranoid owners complaining about low oil pressure in hot weather. On the Surrey Run this weekend it was very warm, I had a rally plaque in front of the grille, the coolant temp was slightly higher than normal (a lot higher after a couple of hill climbs) but the running oil pressure normal. However when switching off heat-soak moved the temp needle to mid-way between N and H (which is still classed as 'normal') and on the restart the initial idle oil pressure was less than 20psi when it is normally 40. However after a few seconds both the coolant temp came down and the oil pressure went up, as expected.
PaulH Solihull

Paul, Are you saying that 60 psi effects oil and air in the same fashion? Air is easily compressed whereas oil is not. Unless you bleed all of the air out of the tube running to the safety gauge, the compression of air will affect your readings. RAY
rjm RAY

Pressure in a fluid acts equally in all directions and is independant of cross sectional area (Pascals tubes http://www.wfu.edu/physics/demolabs/demos/2/2b/2B2040.html)
So Paul is right, if the oil is at 60 psi, then the air must compress until it is at 60 psi to react the pressure in the oil. There is a bit of Heisenburgs principal, the total system volume goes down slightly but it will be minimal.
Stan Best

What temperature do people set their electric fans to come on at?

My car has been running hot but the engine is still new (less than 1000km still). I think it is dropping now but it is hard to tell since the weather has been getting cooler as well.

Increasing my advance from about 14 degrees to around 18 now seems to have helped temperature wise too. That also made a big difference to how well the car pulls and it also eliminated a hesitation I had when the car was cold.

Funny how all these things are related.

Oh, I have a plastic oil line to my gauge rather than copper since I was worried that would work harden and break (thanks to Garth for pointing that out to me). It definitely has a lot of air in it. More air than oil I think. Doesn't affect the gauge. I get steady readings that vary smoothly with rpm.
Simon Jansen

Simon,
Anything greater then 88 degrees, when the mechanical thermostat opens fully. The range rover V8, also a 88 degree C mech mech' thermostat, has an electric thermo switch that goes in the thermo housing that is rated to 92 degrees C. Unfortunately you can't currently buy a reliable version of these. After the original failed I tried three at $60 a pop,no joy usual Chinese product thing. When will we learn?
Now I have a davis craig adjustable thermo switch ($65) and have set it about one quarter of the way from thermostat open to boiling. Purely empirical stuff. I set the temperature gauge to the centre of N when I felt the warm water flow to the radiator using the Gauge Cold end adjuster. Then set the hot end adjuster of the gauge to the middle of H when the pressure gauge began to overflow, the first few bubbles. that way I know exactly when it will boil at 15 PSI.
Quarter of the way might be 95.
Peter Sherman

Thank's Peter. I currently have mine set to come on at 95 on the gauge. Sounds about right then! I keep meaning to slide a thermocouple under a hose to check the gauge is accurate but I have no reason to think it's not.
Simon Jansen

The factory switch is set to come on at 90C for both 4-cylinder and V8, there is little point in having them set any lower. I know some people like to have them set low in an attempt to stop the temp gauge rising above N, but that is unwarranted paranoia, really.
PaulH Solihull

I seem to have solved my overheating problem with my 1970 roadster. When the ambient temperature exceeded 98 degrees F the temp gauge would go all the way to H when idling or slow running. I installed the plastic fan shroud from Moss and so far the gauge hasn't gone more than half way between N and H.
J Brownell

I was thinking that moving the cooler would help uncover the radiator, rather than aid cooling per se. I'm thinking about going back to an engine fan, seems to work better than an electric fan which isn't really big enough due to the shape of the radiator and covers up a few too many fins for my liking anyway. Just need to get a new water pump (I have a long water pump, no room for the fan... silly mistake but wasn;t a problem as I didn't need to use the fan...) and that's a way cheaper proposition than a plastic fan even on ebay!

N
Neil22

"I was thinking that moving the cooler would help uncover the radiator, rather than aid cooling per se"

Eh? What would be the point of that if it *wasn't* to aid cooling?
PaulH Solihull

I installed one of Moss's shrouds, several years ago, and didn't see any improvement. I have a supercharger system and it is a royal pain to fit in place. It also makes adjusting the custom tensioner almost impossible, without special tools. When I recently had to replace a failing water pump and ageing radiator, I left the shroud off and see no decrease in cooling. The only problem was that that I had misplaced the old radiator packing pieces so I made a new set out of some redwood strips that I had lying around. RAY
rjm RAY

Neil I had thought of moving the oil cooler to behind the valance but living on dirt roads I decided it was not worth the risk of a stone chip empting the sump.

Denis
Denis4

This thread was discussed between 06/07/2010 and 26/07/2010

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