Overheating Issues!

[stedolan]

Car: 1991 S2 3B

I've been trying to sort an overheating problem for the past couple of weeks now but have had no luck so far! The engine cools fine when traveling at speed (about 75-80 degrees) but it can get up to 110 when driving through town/traffic etc. Even when I leave the engine running idle the engine still overheats (the temp gauge sits at the second notch above 90 after about 20 minutes).

What I've done so far:-

- The aux rad was in a deteriorated state, so I decided to replace it with a decent second hand one. At the same time I thought it would also be a good idea to change the engine coolant.

- The top hose starts to get hot around the 70 degree mark, so I presume this means the thermostat is working ok?

- Both rads get hot and there are no cold spots - so I don’t think there are any blockages. This is also proven by the fact that the old coolant was clean when I drained it out the bottom hose (no signs of corrosion!).

Also, when the engine is overheating at idle speed the fan only seems to kick in every few minutes and only runs for about 12 seconds. This has no effect on the cooling system and the temp gauge remains at the second notch above 90. Does this sound normal? Surely the fan should stay on until the warning alarm turns off and the temp returns to normal operating levels?

Any advice will be much appreciated!

Thanks, Ste

[Rusty]

Sounds like head gasket I'm afraid. I had the same problems. Quite a shock when you looked at the temp gauge on occasion

Having said that an air lock could also cause this (or a severe leak). Have you bled it through a couple of times to make sure it's good?

The temp gage is from the engine and the rad fan is from the rad switch so unfortunately you can have high temps on the gauge but the fan is not on. I put in a fan over-ride switch to see if it cured the probs but it didn't really. Good mod though as I put it on in traffic when the temp is above 15deg or so and it keeps everything at correct running temp.

[A80Avant]

im sorry but aside from doing an air leak test,i fail to see anything wrong with your engine.
As AAH had posted a long time ago, 2 notches above 90 means 103C not 110.The 110 mark is the dot after the 3d notch.
If you have the OEM thermostat then it is understandable to reach those temps,as the thermostat is working at 98C.You could use a thermostat of 85 or 83C and that would mean that the car would take more time to reach the working temp.Also you could add a lower fan temperature sensor so the fan could kick in sooner.

I have all that and in hot days in Greece in traffic i get 2 notches above 90 which is perfectly normal.You could also get 110C for small periods of time as well without problems as SJM pages suggest.
Finally you could also rest your mind if you would change the main radiator,as mine had been stuck 3/4 after the engine rebuild which was the reason of the overheating.I was getting high readings with all sensors replaced,which directed me to the main radiator problem.

IN all,i think you dont have a problem.If the temp.stays at 2 notches above 90 on most or all circomstances,you should not worry.
Also the fan kicks in only for a few seconds cause it is working on the 1t scale,as it should.If you had the A/C on as well,you would hear it louder and longer,suggesting that you are on 2nd fan level.You would get that if you'd hit more than 103C about 105 and up as well.