VW GOLF coolant level

rjpd77

Hi,

The engine on my 1997 VW golf (40 000 miles) is overheating (engine overheating light on and steam coming from engine) Filled up with coolant screwed on cap and left overnight to see if any leakage occurred. Level was the same next morning. No leak?

Turned on the engine while stationary and after after about 20 mins wisps of steam are coming out from the coolant expansion tank (in fact I can see the coolant boiling in the expansion tank) although engine overheating light does not come on. What is preventing the coolant from doing its job? Coolant pump? Air hole?

Dont use the car much so fancy having a bash at fixing it myself. Bought a Haynes Manual!! Was gonna drain the entire cooling system and refill. Any advice or observations would be appreciated.

Thanks a lot.
Richard

P.S.

(I'm just curious here feel free to ignore)

Id also be interested to know how the cooling system works. I gather the coolant draws heat from the engine thus heating the coolant. But since its a closed system and there is a finite amount of coolant in the system I would imagine the coolant has to be cooled down pretty quickly before it can draw more heat from the engine. How is this acheived? Thanks again

rjpd77

rjpd77 wrote: »

............. How is this acheived? Thanks again

The radiator and when stopped the fan
Does your fan come on before the boiling coolant occurs?
How is the oil level?
Might well not be the water pump, if the pump was dead the water in the rad and expansion tank wouldn't be circulating around and the engine overheat light should defo come on.

If all pipes into and out of the rad are warm than it's not the pump.

Fishtits

I'm guessing its a petrol 1.4.

If so the headgasket's gone.

Follow the Haynes manual exactly and you will do OK, get the head skimmed, keep everything spotless clean.

Good exercise for a DIYer, most Pros would scrap it due to the labour involved...

PS the 1.4 was a carry over from the 70's... its a dog.

mondeo

Sounds like the head gasket is blown to kingdom come, all that pressure coming out of the system like that.

exaisle

It's possible that the seal on the expansion tank cap is not actually sealing properly....Am I right in thinking that if the coolant is not under pressure then the boiling point is lower?

George Dalton

It could be the head gasket but there are some other possibilities that need to be ruled out first. The thermostat housings often break on these internally which prevents the thermostat from opening, this will cause the symptoms described by the OP. It is also worth checking the operation of the radiator fan. It could possibly be the water pump or even the expansion tank cap as suggested above. I certainly wouldn't jump to conclusions about the head gasket anyway.

OP it sounds like you may be out of your depth regarding diagnosing this one. But any half decent garage should be able to tell you what is wrong pretty quickly so that is probably the best option in this case to avoid any engine damage or replacing head gaskets or other parts needlessly.

rjpd77

Hi,

Thanks for all the input.

I think you're right George I am out of my depth Haynes Manual or no. I'll be visting a garage soon methinks. But at least I'll be able to use a few of your quotes to sound cool at the garage!!

I still amazed that incoming air and the fan can reduce the temp of boiling water (thats all coolant is right?) sufficently to keep the engine cool.

Excuse my ignorance Fishtits but "Dog" is good as in Hardy and reliable?

Thanks again all for taking the time.
Richard

coylemj

exaisle wrote: »

It's possible that the seal on the expansion tank cap is not actually sealing properly....Am I right in thinking that if the coolant is not under pressure then the boiling point is lower?

You are correct, the lower the pressure the lower the boiling point which is why you can't brew tea at the top of Mt. Everest, the water boils at too low a temperature to infuse the tea. It also works the other way, if you keep water under pressure the boiling point is increased, this is how pressure cookers work.

If steam is coming out of the expansion tank and the engine doesn't think it's overheating, it suggests the water is boiling at 100 C which in turn suggests that it's not under pressure so I'd check to see if the expansion tank cap is screwed on properly, won't cost you a penny and could fix the problem.

exaisle

...and maybe let us know the outcome.... :-)