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Discussion Starter · #1 ·
Hi all, I need some advice...

I have had coolant loss issues with my 110 BHP GT TDI Golf Mk IV for a while. I have have done many things to exclude the obvious easily fixed problems and am 95% sure that its the head gasket leaking gas into the water, over pressurising it and forcing it out through the over pressure valve in the expansion tank cap.

I just wanted to get as many opinions as possible to confirm my diagnosis before we change the head gasket this weekend.

Here are the symptoms:

No coolant loss when engine not running.
No oil in water, no water in oil (that i can tell)
Rusty colour in the coolant (may be due to lack of inhibitor at the moment, but seems to come back quickly after renewing).
Water temp bang on 90Deg C once up to temp, gets to temp easily.
Coolant fans work correctly.
Water is visable having escaped down the over pressure overflow pipe after a run. wet patch on panel underneath and wet at the outlet. (I have changed the cap and checked o-ring seal)
No other detectable leaks.
If engine has been on a run and then left to cool overnight a gushing noise and coolant rise occurs when remove exp tank cap.

So what do people think? Is it def the head gasket?

Thanks for any advice!

Adam
 

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Sounds more like an air lock in the cooling system. If I read you right, the coolant is just water which means that it has been drained and refilled. Was the system bled properly when that was done? Get your coolant checked for combustion contamination. It's a simple test that any garage etc should be able to carry out, if that's clear then you don't have a blown head gasket.
 

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Discussion Starter · #3 ·
Hmm, had thought it was this too. Can an air lock cause it to over pressure in this way? I am losing about a litre per hour on the motorway. Also I have drained and refilled it twice, being careful to pump it through by compressing lower rad hose and the problem has remained.

I do hope you are right though, sounds cheaper!

How do I get my coolant checked for combustion contamination?

Thanks for your help!
 

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sounds like head or gasket probs, are the hoses pressurising up? you say its been using coolant for a while, cars dont normally just develop air locks. whip the head off and check it out
 

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ĢЁΞЯĐϋЪ said:
I do hope you are right though, sounds cheaper!

How do I get my coolant checked for combustion contamination?

Thanks for your help!
Take it to garage, even Kwik-Fit should be able to carry out the test. They just take a small sample of coolant and a re-agent which reacts with any combustion residues and gives a reaction.
 

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Just a thought, is the water pump working, they pack up often this is a common problem on them due to the plastic impeller on the pump and can often give various different problems, usually they just overheat, but they don't always, just take the cap off the expansion tank and start the engine let it warm up a little until the thermostat opens, if you can see the coolant coming through the little pipe near the top into the expansion tank then it is probably not the problem, if it is not coming through then take the small hose off and get someone to rev the engine if it dribbles through slowly then the water pump is knackered, if none comes out then the pump is also knackered, as suggested before I would also get the coolant checked for combustion contamination but check the water pump first as it won't cost you a penny, if it's not the pump then as you say it unfortunatley looks like it may be the headgasket :(
 

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Discussion Starter · #7 ·
Thanks for advice guys.

Autocraftkid: I have heard about the water pump problems and intend to change it when do timing belt (mine is a 98 so will def have plastic impellor- what were they thinking!) I have taken the small pipe off the expansion tank and have seen water come through in spits and spurts, but that was just on tick over. Will check later once its cooled with revving.

joe kelly at beachside: Yeah although the problem did begin around the time I replaced the temp sensor and refilled coolant. Although the fact that it seemed to get worse with thime makes me think its the head gasket.

clarkson46: I will take it to quickfit or somewhere tommorrow which will answer the question either way I guess. If its gone then will have new gasket, timing belt and water pump going in at the weekend! Would rather be at the pub though! :-(
 
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