GolfGTIforum.co.uk
General => The garage => Topic started by: justin3779 on 09 December 2010, 18:13
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hi guys ive got a mk3 2.0 8v gti which has run absolutly great until last week when it started to overheat really bad. the temp gauge is going to the top and the oil temp is going through the roof as well ( it hit 120 yesterday ) the rad seams fine and the fan works but its getting that hot its blowing steam. i had the plugs out out checked the cylinders and theres no water so the head gasket aint gone. i couldnt find a thermostat either. anyone got any ideas ???????
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If you want to check the thermostat then let the car warm up and when the fan kicks in then check the two radiator hoses. The top one and bottom one should be hot. If the bottom hose is still cold then the thermostat is not opening and needs replacing. Just don't let the engine get too hot :wink:
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to check teh thermostat you be able to takem it out and put it in a bowl with boiling hot water
. then it will open up once it reaches a certain temperature , if not its broke
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do you think it might be the water pump ?????
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Coud be the water pump Mate but check the thermostat first as this is cheaper. Also try driving the car with the coolant reservoir cap off. If yours has the Blue cap then these are prone to fail and the Black caps are more reliable. Always try the cheaper easier stuff first :wink:
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i dont get it ???? how can the bottle cap affect it, cos it is a blue one
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i dont get it ???? how can the bottle cap affect it, cos it is a blue one
Not sure how they differ Mate but heard a few stories of the Blue one failing. If the rubber seal inside fais then the pressure system is not right and believe it or not it does have an effect. Try driving it without the cap to relieve the pressure and see if it makes a difference. It's a free test and may work or may not :wink:
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I thought the black caps were bad and the blue one were ok?
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I have always stuck to Black caps and never had a problem. Maybe someone else can confirm which way ??
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its the black ones which are early, blue ones were the replacment. but i believe its the mk2 pre-90 caps that the design actually changed black to blue, from what ive seen the mk2 90spec + mk3 caps are very similar black to blue. if the system isnt sealed then the coolant may boil, and if that happens you get airlocks in the system.
have a read:
http://www.golfgtiforum.co.uk/index.php?topic=106380.0
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update guys, ive got the blue cap and it seals fine. the car will run fine for about 10 miles then the water temp goes through the roof and so does the oil temp to the point were by the time ive gone from birmingham to coventry ive used 5 litres of coolant. i started it up today and the bottom hose of the rad gets hot almost intsantly so am i guessin its the thermostat ????
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Does the bottom hose feel like it's full of hot water or hot air ??
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If you've used coolant, then there's a leak, the head gasket has gone or the oil cooler has gone.
Sniff test the coolant, compression test the cylinders, investigate the oil.
5l of lost coolant, it should be very obvious.
Oh, and never drive without the expansion tank cap on.
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If you've used coolant, then there's a leak, the head gasket has gone or the oil cooler has gone.
Sniff test the coolant, compression test the cylinders, investigate the oil.
5l of lost coolant, it should be very obvious.
Oh, and never drive without the expansion tank cap on.
Why not Mate....I was told by a garage that if the pressure is building up and you remove the cap the pressure is relieved enough to drive a short journey rather than sit at the side of the road.
But agreed 5l of coolant is a lot and a leak would be obvious. Is the water coming out when you switch off the engine ??
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no wter is coming out anywhere, iv checked the cylinders and no coolant so its not the head gasket. im just totally confused
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its losing so much water cos its heating it up to the point where its blasting out as steam
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Mine was similar when I first bought it. One of the to hoses developed a minute pin hole and I got an air lock in the system. Flushed out the coolant system and all has been well since. Follow the link pasted up on Page 1 of this thread to try to get rid of any airlock. This is the reason I said take the reservoir cap off as this would release the pressure and if the car drove ok for a short distance you would know it is an airlock and could set about sorting it out. Also did the bottom hose feel like it was full of hot water or hot air as this would explain the thermostat working or not.
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If you've used coolant, then there's a leak, the head gasket has gone or the oil cooler has gone.
Sniff test the coolant, compression test the cylinders, investigate the oil.
5l of lost coolant, it should be very obvious.
Oh, and never drive without the expansion tank cap on.
Why not Mate....I was told by a garage that if the pressure is building up and you remove the cap the pressure is relieved enough to drive a short journey rather than sit at the side of the road.
But agreed 5l of coolant is a lot and a leak would be obvious. Is the water coming out when you switch off the engine ??
Your cap is responsible for releasing pressure. The system needs to maintain a pressure of about 15 psi so that it can prevent the water from boiling. If it boils, it develops air locks and causes much larger problems.
If 5l is being blown out as steam, then you must be able to see where it is coming from?
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I once took a 4x4 into the garage for overheating problems and was told the head gasket was shot and quoted £1200. Removed the cap and drove home 12 miles with no further overheating problems. Then changed the cap for a new one which cost £3.99 and the problem was gone. Sometimes it can help to remove the cap to release the pressure. I obviously would not reccommend driving for long periods without the cap but either as a test or a quick fix to get you home it can and does work as this event proved for me.
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I once took a 4x4 into the garage for overheating problems and was told the head gasket was shot and quoted £1200. Removed the cap and drove home 12 miles with no further overheating problems. Then changed the cap for a new one which cost £3.99 and the problem was gone. Sometimes it can help to remove the cap to release the pressure. I obviously would not reccommend driving for long periods without the cap but either as a test or a quick fix to get you home it can and does work as this event proved for me.
I can't see what is it gain by doing it as a test?
On a car that is working fine, running it without a cap will cause the water to boil over, develop an air lock and leak coolant.
On a car that has an airlock, running it without a cap will help remove the airlock, but will then subsequently boil over, develop another air lock and leak coolant.
The only time the cap should be off the car is when it is stationary, I can't advise driving round without it on.
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I wouldn't drive with the cap off either. As Ben said, it needs pressure to work properly otherwise it'll cause bigger problems.
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just had a thought, when i took the car in to have the clutch done the guy said that there has some bult up of white stuff on the coolant pipe that attaches to the front of the block by the spark plugs so he cleaned it all off and i noticed steam coming from there there when it overheats so colud that be causing all the problems ??? if it boils over when it loses pressure........
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Read my earlier post Mate about mine overheating when I bought it due to a pin hole in the top hose. :wink: Sounds like an air lock to me so I would revert right back to Page 1 for the guide on how to get rid of an air lock.
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If there is a genuine leak, then you can't remove an airlock until the leak is fixed.
Run it up to temp, pop the bonnet and look for your leak, doing anything else is futile.
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if its getting that hot that quick, the problem is more than a leack, remove the small pipe that feed into the coolant resovor, fill coolant resovor, start engine an rev. there shoudl be a good flow of coolant out of said pipe. if not remomove the waterpump and check to see if the inpeller is still on the end of the shaft and has it's blades still intact. it probobly dosent. you will also need to fit a new thermostat they don't like being cooked and tend to lock open