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Model specific boards => Golf mk3 => Topic started by: aminorthreat1 on 02 March 2010, 16:09
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ever since i flushed and replaced the coolant in my 16v after being driven hard for 5-6 miles the coolant boils over and out the expansion tank. engine temp is normal, so i was worried it was the head gasket. so ive done everything, compression test, cylinder leakage test, and checked for exhaust gas leaking into the coolant. none of which indicated a leaky head gasket. i did manage to squeeze some air out of the pipes once the hole thing had cooled down and i had encountered an airlock when changing the anti-freeze. but with the amount of air i've squeezed out and amount ive topped up the coolant im fairly sure i've got rid of the airlock. so now im thinking theres maybe a block in the radiator? anyone else have any ideas?
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ever since i flushed and replaced the coolant in my 16v after being driven hard for 5-6 miles the coolant boils over and out the expansion tank. engine temp is normal, so i was worried it was the head gasket. so ive done everything, compression test, cylinder leakage test, and checked for exhaust gas leaking into the coolant. none of which indicated a leaky head gasket. i did manage to squeeze some air out of the pipes once the hole thing had cooled down and i had encountered an airlock when changing the anti-freeze. but with the amount of air i've squeezed out and amount ive topped up the coolant im fairly sure i've got rid of the airlock. so now im thinking theres maybe a block in the radiator? anyone else have any ideas?
Hi mate
mite be the water pump buddy mine doing the same and i've just done my head gasket and timing etc. Got a new pump today so fitting it tonight. It because the engine is getting to hot and the pump is not opening the thermo quick enough so it pushes the hot water back and out of the overflow on the expansion tank.
Water pump £21 includes Vat from GSF
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cheers mate, ill look into that. also just had a thought, is the PAS and water pump ran off the same belt? coz my PAS belt is slipping on full lock and needs tightening. i know theres two belts down there (besides the timing belt) one runs the alternator and the other runs the AC compressor.
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cheers mate, ill look into that. also just had a thought, is the PAS and water pump ran off the same belt? coz my PAS belt is slipping on full lock and needs tightening. i know theres two belts down there (besides the timing belt) one runs the alternator and the other runs the AC compressor.
I'm not too sure buddy, I changed the thermo the other day and the power steering pump and I didn't see the water pump attached to the PAS. Have you tried tightening it up mind did the same and I tightened it up and it was fine.
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just had a look, the outside belt drives the PAS and waterpump, im guessing the bottom one is the PAS pump (the one with the tensioner) and it looks as if its fully tightened. i'll have to jack it up to get a proper look since the things on its arse with a vr6 splitter so acces isn't easy, so i could be totally wrong lol. but i'll have a good look at it this weekend.
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First try changing the expansion cap.
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+1, sounds like the o ring in the expansion tank cap is perished or 'nipped'.
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is that a common fault on them? ive heard something about the pumps having plastic fins which are pretty weak, cant remember if that was the mk3's or not tho.
the cars been sat a good 3 hours and the engine is cool but the coolant is still right to the top of the expansion tank, it was filled to just above min.
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How long does it take for the pressure to build up from cold?
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few mins, not long. maybe 5. sometimes the temp gauge can take a while to rise as well but i was thinking thats just the new coolant, but 4 miles normal driving before it climbs?
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First try changing the expansion cap.
+2 I would do this as a 1st step.
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If the coolant system is overpressuring so quickly i would suspect the headgasket.
Try slowing releasing the pressure by undoing the cap, be careful not to get scalded.
If the system pressurises really quickly again then i would say the headgasket has gone.
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If the coolant system is over pressuring so quickly i would suspect the headgasket.
Try slowing releasing the pressure by undoing the cap, be careful not to get scalded.
If the system pressurises really quickly again then i would say the headgasket has gone.
Mine was doing the same matey, i changed the expansion tank for a new 1 and a new cap, still did it, new head gasket fitted 4 days ago and lots more lol. Had a new thermo and water pump fitted and still did it, Had a compression test done on it today this was fine. Me and my mechanic mate messed around with it for hours today draining the system and filling it up again god knows how many times we did this and still it pressured up.
The hose at the top of your expansion tank when you take it off is there any water coming out of it also the small hose where the ecu sensor is located just at the front of your engine block the one with the hoses going into it. The smallest hose just to the right of this little housing take this hose off and check to see if the water is coming out of this housing. On mine it wasn't nor was it coming out of the return hose at the top of the expansion tank. We think we eventually found the problem it was a blocked pipe the small one i mentioned coming of the little housing this was blocked with some hard crap which we had to force out. Touch wood this as solved the problem. The water level now stays at max. Hope this helps buddy. Steve.
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right i'll check that, im pretty certain the head gasket is fine, i spent long enough testing it and i had no probelems at all before i changed the coolant. i've also ordered a new header cap. cheers for the help.
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right, just started her up, coolant boiled over before it got up to temp. the heaters are now only blowing cold, and there doesnt seem to be any coolant moving around the system at all. im guessin its the thermostsat or the pump, so i might aswell do both.
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as stevo says, check the thin hose. with the cap off run car from cold, when you rev engine there should be a spray of coolant out of this thin hose to the top of the header tank. if not the thin hose is blocked, or the waterpump is knackered.
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as stevo says, check the thin hose. with the cap off run car from cold, when you rev engine there should be a spray of coolant out of this thin hose to the top of the header tank. if not the thin hose is blocked, or the waterpump is knackered.
Amino
Just an up-date mate, mine still ok the water level staying at max, if there's water coming out of that hose i told you about then it's more than likely either the thermo or the water pump dude, Water pump £21 GSf thermo £4.
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cheers. hopefully be able to do it this weekend.