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MG MGF Technical - Ford overheating help (no F content)

I'm afraid this has no F content - but as I cannot find a nore suitable forum, thought I might pose the problem here!
A friend of mine has a kit car powered by a 2.0 OHC 8v pinto sierra engine. The problem is that the engine always runs hot. It has never quite overheated yet, but on hot days it does need to be driven with one eye on the temperature guage!
We have removed the thermostat completely, but the heater still gets warm, even on cold days, and we have recently fitted a new double core radiator, but the car still runs very hot.
In desperation we took off the head over the weekend, but no signs of HGF, so we are now reassembling (with new gaskets etc.)
Anybody got any ideas or suggestions of what else to check?
Jason H
Jason H

Water pump?
Radiator fan not comming on (if car overheats whilst driving slowly)
Not enough room around the radiator for air to flow out of the car?
Engine in too tight a compartment?
Water not holding pressure?
Will Munns

Jason,

If this Sierra engine still got a fan with a single blade (like a lawn mower) replace it by a decent multi blade fan(box). Sierra engines are notorious for not cooling enough if built over into a kit cars, because of lesser space for air flow. You can easily remove the old fan and tie-strap the new box to the radiator.

Peter
Peter Roos

How are you sure that the engine is actually running hot? Seems a daft question I know, but if the only evidence for a hot engine is a temperature guage, then I'd double check that the engine really is as hot as you think it is before throwing more money at a problem that might not exist.

If you are 100% sure that the engine is too hot with a secondary temperature measurement, then Will's and Peter's suggestions are excellent places to start checking and re-checking: cooling airflow could be the problem here.

What kind of kit car does your friend have? A 'Lotus 7' clone?
Rob Bell

Thanks for the help - the car is a "Beauford" a thirties style open car - with a massive upright grill and a huge bonnet and hence loads of under bonnet space - room for 2 engines (makes a change from the F!).
We have already replaced the fan with a multi blade unit (it is on a viscous coupling).
We belivee the engine runs hot based on the temp gauge, which has been replaced, a second temperature sensor and gauge fitted temporarily a few weeks ago, and the hot air from the heater even in the winter with the thermostat has been removed.
The water not holding pressure is one thing we have not checked - no visible leaks , but it does use some water. I had put this down to the engine running hot, but perhaps a pressure test is in order!
Jason H
Jason H

Ah yes, I know the ones.

If the sender and guage have been replaced and are thought to be reliable, then you have a problem with the circulation of the water.

Water pump is one area to check, the other the plumbing of the coolant circuit. Is hot water getting to the radiator as it should?
Rob Bell

You say the thermostat has been removed, have you also blocked the bypass pipe? stupid question I know, but if you have just 'removed' the thermostat then the water will just bypass the radiator as the bypass is easier.
I would expect the heater to be warm even in the winter, just to take longer to get to temp.

Will
Will Munns

Will,
I hadn't thought of that!
But if that is the case, then with a thermostat fitted which opens, the water would still just go down the bypass and not go through the to the radiator. What makes the water go through the open thermostat to the radiator as opposed to round the bypass?
Jason H
Jason H

The thermostat closes the bypass as it opens the radiator, Get youself a G-Cramp and clamp the bypass hose shut.

Will
Will Munns

Will,
Already got a G clamp, so when it is reassembled I will try that out.
Thanks, Jason H
Jason H

Will,
I have just phoned my friend with the car, apparently there is no bypass. The thermostat just blocks the water flow until the opening temperature is reached, then it opens and the water circulates into the radiator. Seems surprising but apparently this is normal on older engines!
Jason H
Jason H

When you say the temp sensor, I guess you mean the Water temp sensor?
If the water is not being pumped around the system fast enough I would expect (on a good airflow) the water leaving the radiator to be very much cooler than when it enters. Check this.
If the radiator is full of gunk (quite possible on an old radiator) then the water may be passing thru it, but not reaching most of the cooling fins, if this is the case I would expect the temp to be very hot at the exit of the radiator. Check this.

If the radiator is gunked up then either replace the radiator, or run a lot of water backwards thru the radiator.
The cars heater matrix behaves like a bypass, even if the thermostat has no bypass pipe - is it the original pipework or has it been replaced with a wider pipe or diffrent matrix? If so then try G-cramping the pipes to the hater matrix (might also look like a slow water pump)

Will
Will Munns

This thread was discussed on 02/09/2002

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