Morris Minor Owners Club

Hi all I have a problem with a slight over heating engine.
The engine was an emergency replacement after my old 1098 gave in just before the last Barnsley jogle. The donor engine was an unknown quantity but did the joggle with no problems.
Except it ran at a temperature of 90 not 80 as I think it should have.
I changed the thermostat but to no avail so I am now running without a stat at all but it still runs at 90. I have also noticed a slight oil mark on the seam of the cylinder head and block.
Has the gasket gone? Or
Could the water capillaries be blocked?

Presumably you are using all the original items(radiator, etc) which were used on your original engine without any over heating? If so then, if the new engine is otherwise running as it should be then it suggests that the waterways may well be furred up. Either that or you are running too far retarded or your fan belt is slipping.

Cheers Willie
Yes, every thing is standard as was on the old engine.
I was wondering if some kind of rad flushing chemical might do the trick? IV not had any experience of them. On the other hand, is it just a case of taking the head off and cleaning what I can and try again?

I have flushed engine with water from hosepipe forwards and backwards but to no avail

There are several products available for removing the furring, in the past
I have had to remove the cylinder head and clean out every waterway hole
in the block and the head with the appropriate drill size(cleaning them out NOT drilling them oversize)! If you wish to avoid removing the head then
you could fill the engine up to the thermostat housing with a solution of 'kettle
descaler' and leave it overnight. Reverse flushing of the radiator usually
produces a lot of gunge but, your other engine didn't overheat!

Is it really overheating - or just the gauge showing a high reading ? Are you losing any water ?? I'm surprised it would overheat with no stat fitted - the Minor radiator is huge and should cope with just about anything. Verify the true temperature with a thermometer in the rad - but take care when removing the cap in case it boils up on you!

Another thing worth checking as I suffered froma hot running car that proved a pain to locate until the water pump leaked and when changing it I automatically went to change the bypass hose and was amazed that it appeared to be almost blocked and the bypass stub was completely bunged up so I did the same as Willie and removed the head and cleaned out everthing I could, and that solved the hot running issues, but try Willies suggestion of Kettle descaler 1st as its easier.

My brothers minor kept over heat a good back flushing, just using a hose to both engine, heater and rad helped.

Well, I’ve just tried putting the de-scaler in the engine. I used the one that washing machines live longer with. I ran it up to temperature and added the maximum amount stated for washing machines. (Pre mixed in hot water first) I let the water pump pump it round for a minute or two, then stopped the engine and left it to stand for three hours.

I then flushed the engine and radiator forwards and backwards until the water was coming out clean. After reconnecting the hoses and topping up, I ran it back up to temperature. However, it was still 85ish so I checked the rad temperature with 2 different thermometers and they both showed 80 degrees exactly.

So, I think as Bmcecosse said it could be a discrepancy in the temperature gauge itself.

Thanks to all for your help and advice.