Big overheating problems

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acf8181
Posts: 809
Joined: Tue Apr 05, 2005 12:00 am
Location: Norwich

Big overheating problems

Post by acf8181 »

So when i did a trackday a while back i had the car try and overheat, which i put down to an air pocket in the coolant system as it was fine on road before and after.

However, its now overheating on road, and very quickly!

First issue is fan....they don't appear to come on at all, however i pulled the plug off the rad temp sensor and they came on. It still overheats with them running all the time, so that's not the cause of the overheating, but is obv not right.

I took the sensor out and did the test where you boil it in a pan of water and check resistance at various temps.....all was correct, so don't think that's the cause of no fans. Whats next most likely thing to cause the fans not to come on?

As for the overheating....engines runs fine, no leaking from any bit of the cooling system is obvious (tiny small leak out rad, but not to level of losing about 6 litres of coolant i keep having to put in the car!). Pipes appear same temp coming out of and in of radiator when car is warm. Could thermostat be the cause (seems to work as when warm coolant colour changes - i'm only putting in straight water at this point - suggesting to me its 'releasing' coolant into the engine).

I'm just trying to work out if i haven't thought of anything easy to check, before i get a block leak test kit to confirm its the headgasket (compression leaking into coolant)!

Suppose other thing is water pump....is it possible for one to stop pumping coolant around engine? Or would that be obvious?
tiff_lee
Posts: 384
Joined: Thu Jun 04, 2015 2:18 pm

Re: Big overheating problems

Post by tiff_lee »

" but not to level of losing about 6 litres of coolant i keep having to put in the car!"

You should of opened with this, how often you having to top it up?

"Pipes appear same temp coming out of and in of radiator when car is warm"
same temp as in both cold or both hot? if both hot i'd be satisfied water pump and thermostat is working.

If you are regularly losing 6 litres of coolant with no visible leaks and the car is overheating i'd wager head gasket, i've had it myself on a C20LET, the car still went like a bullet but gasket was gone.
Nails
Posts: 1398
Joined: Thu Aug 07, 2008 10:06 am
Location: durham-ish

Re: Big overheating problems

Post by Nails »

You also say the radiator is leaking a small amount? Have some one rev the engine while watching your leak. Its more than likely to squirt out under pressure. This will also be letting air in and the system wont be pressurising properly either.
A garage could do a leak down or sniffer test for you also quite cheaply.
killerferret666
Posts: 659
Joined: Thu Jul 26, 2012 8:00 am

Re: Big overheating problems

Post by killerferret666 »

I had exact same problem

Engine running hot
Eating water
No leaks
Pipes in and out of radiator don't appear to feel that different anyway as they radiate heat so both are still warm now.

To be honest it's the eating water statement if it's not leaking it's going somewhere and generally that can only be out the exhaust.

Anyway my issue was the headgasket
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abovetherim
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Joined: Wed Feb 16, 2011 8:49 pm
Location: Leicester

Re: Big overheating problems

Post by abovetherim »

I also have also had similar symptoms as you. It started by struggling to start, first start after a couple of days. I then noticed the heater going cool (ie coolant loss). Found a weep on the rad so I bought a new rad. I then found a weep/p1$$ on the hose connection to the heater valve so I tried to seal this but I failed as the system was pressurising and heating up far too quickly.

My theory was the over pressurised system from combustion gasses took out the old rad and found the weak spot at the heater valve.

Dived in and changed the HG and when I took the old one out it was in good condition apart from a small sooty build up on the combustion ring between a waterway and cylinder 3. I sorted the ill fitting hose for the heater valve also. With the new HG it now hold temp bang on and has lost zero coolant in 2 weeks.

All this said there are pipes around the oil filter that could be leaking. One of the heater feed pipes runs from the engine bay under the car above the fuel tank and is prone to deteriorating.

Hope you sort it
acf8181
Posts: 809
Joined: Tue Apr 05, 2005 12:00 am
Location: Norwich

Re: Big overheating problems

Post by acf8181 »

Seems you are all backing up my thoughts!

Guess i gotta rip it apart...booo! Oh well, suppose i should really do cambelt anyway (no record of it), so can do it all in one go!

Any ideas on rad fans?
acf8181
Posts: 809
Joined: Tue Apr 05, 2005 12:00 am
Location: Norwich

Re: Big overheating problems

Post by acf8181 »

oh, and i suppose its possible the head is cracked.....if so, is this likely to be easily visible?
killerferret666
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Joined: Thu Jul 26, 2012 8:00 am

Re: Big overheating problems

Post by killerferret666 »

acf8181 wrote:oh, and i suppose its possible the head is cracked.....if so, is this likely to be easily visible?


When fitting my metal head gasket I had the head refaced and at the time also pressure tested.

£50 for pressure test and about £35 for reface
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acf8181
Posts: 809
Joined: Tue Apr 05, 2005 12:00 am
Location: Norwich

Re: Big overheating problems

Post by acf8181 »

Started taking my head off now! (ok, well, i say started, i undone downpipe bolts and i think crank pulley bolt loosened - awaiting other half to come home to press brake so i ca be sure its loosened!)

Will be a bit at a time job due to (lack of) finances!
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