I am really mad about this!

[GR40]

My G40 seems to have developed a habit for overheating! Now I am really irritated about it because it is the 4rth time I have changed the thermostat and the plastic tubing around it in a period of under a year and the damn thing keeps on leaking all over! Not even silicon didn't cure it! the bolts keep on getting loose and the car every summer needs a 4 hour inspection to find the damn leak! Is there a solution to it, like aluminium tubing! The temperatures where I live reach about 40oC every summer, but it seemed able to cope with it before! Is it normal for the car to reach 100oC on open road for speeds like 140km/h?

[PeteG40]

when you replaced the thermostat housing - did you get new bolts too, with the new housings they require huge self tapping screws, not the normal bolts that came on it.

I've seen a few new housings, with old thin pitch bolts - never gonna seal.

Just a suggestion!

Pete

[GR40]

The new housing came as a set with new bolts! It does seem way fragile though beeing plastic and I am concerned that it might be bending from heat up to the point it starts leaking!? Who ever though of making a thermostat housing out of plastic???

[PeteG40]

never had a problem - bit of silicone against the block and on the thermostat - then just nip the bolts round thermostat housing up.

[GR40]

Is it possible for my a**hole mechanic to have puted the thermostat the wrong way in causing it not to work properly!? Everything seems to work perfectly as soon as I stop to check it! both hoses to and from the radiator are hot, the fan is on and the entire rad is hot to all its length! I did have the same problem in the past and was caused by the thermostat beeing stuck half open thus overheating and melting the plastic housing! I am thinking 82oC thermostat this time!

[JIMMYP]

have u check to see if ur waterpump is circulating the water if thats gone then it will cause overheating. dont think u can get thermostats wrong way round they should have the correct shape for it to fit in. or could b possibly head gasket.

[GR40]

The pump has les than 2000km! I don't even want to think about a head gasket change! I did noticed the other day the fun going on at over 95oC no excuse though for it not to cool down at 140km/h! Is there a way to check if the gasket has gone bad? There is no indication of oil in the water or the other way around!

[JIMMYP]

sounds as though its liquid tight but might not mean its gas tight. one way to check is to take top of expansion bottle run it and smell in the bottle for a petrol smell if it smells like petrol its a good indication if it smells of fish then its just ur anitfreeze. another way is to leave expansion cap on run it and if the rubber coolant pipes go rock hard in around 1 to 2 minutes that another indication that its gone cus the gases from the cyclinder are getting into coolant and pressurising it up. or the other way is ask ur mechanic if hes got a head gasket leak checker aka a lipnas tester. i think thats how its spelt and if the blue liquid in that turns yellow when sucking in coolant vapour then that indicates its gone. if ur travling at 140k it should b keeping itself cool because the air being rammed into the rad should cool it. the fan shouldnt have to run until idling where no ramming effect goes on. hope that helps.

[GR40]

thnks mate, that does help!

[GR40]

Well I did both and there was neither smell nor hoses being swelled! The problem seemed to be elsewhere! I did found out that one of the bolts that holds the exhaust manifold had snapped (apparently a common problem to vws of that era) and a second one snapped as soon as I touched it so apparently the cylinder next to the thermostat housing had serious gas leak! Probably pissing really hot gasses to that area! I did use new gasket and bolts and the leak was fixed! Now it only overheats just a bit but I would love to eliminate that too!