Overheating donkey!

[gambler]

I’ve been having problems with the S1 overheating. From cold, it will heat up and cool itself back down ok. Once it’s had a bit of a run, the temp goes up, fan goes on and it just gets hotter and hotter. A bit of a rev sometimes helps but not all the time. Bleeding seems to help a bit but after a couple of runs, it goes back to the old problem

It had a new radiator last year. The fan also now seems to kick in at 94 rather than the old temp of 85.

Any ideas?

[scott.a]

could be the waterpump. Could also be the thermostat.

[Stephen]

Are they not all prone to a 92/93 fan turn on temp?

[Victor Meldrew]

Head issue... leaking exhaust into the cooling system.. similar symptoms to a water pump.

1. The car will run and sit at idle for hours without issue?
2. After a good spanking you get a temperature spike that only gets worse? That will be the exhaust gasses cavitating in the pump. A good rev starts it circulating again. Problem goes away for a little while.
3. Don't believe the indicated temp gauge to be 100% correct, it can change when the radiator fan kicks in due to a change in voltage. Turn your lights and heater on and off and watch to see if the indicated temperature changes.
4. Loosing coolant through the expansion cap?

Been there... got the T shirt....

[UncleRon]

Funny I was looking at pictures yesterday of your Elise with N3 TUT behind when Andy lent me it to take to Folembray a few years ago - Fond memories!

Agree with the guys above my S1 Elise radiator fan does not kick in till well into the 90's and that's a pretty rare occurrence for me. Waterpump and thermostat are possible issues but in the first instance and for £8 odd I would probably just try a combustion leak tester kit like the one in the link below to see if there is an obvious sign of exhaust gasses in the coolant just to get a feel of a potential head gasket or cylinder issue. If the fluid goes yellow then maybe back it up with a compression test.

https://www.ebay.co.uk/itm/BT-1-100ml-C ... SwHHJdZweV

If these checks come back clear and you have bled the full system using all the bleed points and the radiator gets hot as normal then I would probably target the water pump next, fit a new cam belt & tensioner at the same time and take it from there.....

[gambler]

Thanks chaps,

Have had the a sniffer in the head gasket, which has recently been changed. All is well with the head gasket

[robin]

Yeah, I still think it's the head. Might be opening up when hot. Here's the thing - you're getting some sort of coolant loss/gas in the coolant - where in the system is that happening? Remove all the spark plugs and see whether one is much cleaner than the others. Also give it a spanking so that it overheats, then let it cool down enough so you can take the cap off - BE CAREFUL - then do the hydrocarbon test.

Do you get any coolant on the floor when it's standing?

[Victor Meldrew]

Yeah, I still think it's the head. Might be opening up when hot. Here's the thing - you're getting some sort of coolant loss/gas in the coolant - where in the system is that happening? Remove all the spark plugs and see whether one is much cleaner than the others. Also give it a spanking so that it overheats, then let it cool down enough so you can take the cap off - BE CAREFUL - then do the hydrocarbon test.

Do you get any coolant on the floor when it's standing?

It took around four attempts the first time to diagnose the gasses in the coolant on my car.

I think that the gasses may pool at the radiator end. Put your hand on the radiator to see if it is hot over the whole surface area. I was finding cold spots that went away when it was given some revs. That would be the gas pockets. Try parking the car nose down a hill and rev it a bit before turning the engine off. Should give you the best chance of getting the gasses back into the header tank.

Dan (may you never need to speak his name) took the head off and had it pressure tested, it passed. The engine was rebuilt, new water pump and thermostat fitted and the car returned. Problem still there, eventually got another positive sniff test. Turns out the place he used tested it at ambient temp, not in a hot bath to simulate normal running temp. When cold it was fine, but when hot the cracks opened up and leaked. New head fitted, problem solved.

[robin]

I think the heads are prone to cracking somewhere between the combustion chamber and the exhaust ports - Dave Andrews (of DVA fame) wrote something about it ... though perhaps only an issue when porting the head.

Scott - what head is actually on the donkey?

[UncleRon]

Sounds like it might also be worth seeing what results a compression test carried out when the engine is as close to 90 degrees as possible are.

Probably worth wearing gloves and not as easy working on a well hot engine but careful use of the tools should avoid you getting burnt and by the sounds of things checking the engine compression when it's as close to normal operating temp as possible seems pretty key here.