boiling engine

[vodkakid]

my car has started to over heat and i cant work out why!
fan cuts in, theres enough coolant(the heater still blows hot air)
but there is a small amount of water under what i think is the water pump.
but its strange, some times it cools down for about 5mins then heats straight back upthen goes close to the RED!so i no longer dare drive it, though its my only car.
any ideas please

andy c

[LeeBee]

Air pocket? maybe pulled in by a leaking waterpump?

Cheers

LeeBee

[Roy C]

Thermostat failure (shut)?

Also check the level in the swirl tank (cold), NOT the expansion tank.

Roy

Edited by Roy C on Wednesday 24th October 09:14

[mhibbins]

If you've got a leak in the water pump and it's pulling in air could the water pump just be frothing up a bit of water in the air pocket and not pumping the water around efficiently causing the overheating?

Anyway, I did the water pump on my s3 a couple of months ago and it's dead easy. The pump was 35 quid from a motor factors and the job would have taken an hour from start to finish if one of the studs hadn't broken (fortunately just the head of the stuf came out and I could get the threaded bit out with mole grips but I had to go and buy a new stud.

For the sake of the next owner please use a torque wrench to do the bolts up, it's amazing how little force is required to do them up to the required torque.

--
Mark

[vodkakid]

thank you all i shall look in to this as i there is air pockets forming in the system
ta
andy c

andy c

[vodkakid]

thank you all i shall look in to this as i there is air pockets forming in the system
ta
andy c

andy c

[heath]

Vodkakid,

I have had the same problem myself, that is if the symptoms are the same. Before lashing out on new pumps try this as it won't cost you anything.

The Symptoms: Bubbling sound coming from engine area when your journey has ended, possible loss of water from around front driver's side wheel?

If so, check the caps on the radiator swan neck and on the overflow tank. A lot of service engineers put them on the wrong way around (as the TVR handbook tells them!). The cap with the pressure coil underneath should be on the swan neck (about six inches behind the radiator). The plain cap should be on the overflow\expansion tank.

What may be happening is that if the caps are in the wrong position air escapes from the swan neck as there is no pressure cap keeping it in, hot water goes into the overflow and is then forced out of an overflow pipe which exits near the tyre.

If the leaking air has caused an air lock you will probably have to bleed the system and start a fresh.

Always start with the cheapest thing first. My car no longer bubbles at the end of a journey, I no longer get airlocks and the temperature is cooler. Just remember to check the caps after each service!

Good Luck.

[vodkakid]

i replaced the swirl tank cap the other day and yet it still leaks at pressure
but all the symptoms you say are spot on !!
ill try again
cheers
ac

andy c

[johno]

The water pump is designed to leak water when the pulley bearing has gone. There are holes round the bearing housing which are visible.

If you check the pulley by getting hold of it and wiggling it ( no comments now ) to see whether it has any play in it.

I replaced the pressure cap on my swirl tank for a new one this year with the same pressure rating and it leaked coolant. Put the old one back on and no problem.

There seems to be a difference in the depth of the dishing of the cap which reduce the pressure it fits and causes this. I'm not certain about this though.