Losing coolant

[adbett]

Currently getting through about 1.5 litres of coolant every 500 miles (I do a high mileage so this is actually only over a few days!). Been losing a little recently but now getting pretty bad. Going to have a look over the weekend and see if I can trace the problem but could use some ideas where to start....

car is '98 1.9TDi, no puddles or drips appear under the car, no obvious steam or dried coolant around hoses when looking under the bonnet. Car starts and runs the same as ever, no loss of power. Temperatures the same as usual.

no wet carpets either!

any suggestions?

 

[John@ECM-TECH]

Have your water pump checked, they lose water when they are worn by design I think.

Any squeaks ?

 

[marms]

I think it's also fairly common for the seal on the expansion tank cap to leak. Might be worth a look as this is a very cheap fix.

 

[adbett]

no obvious squeaks, is there a good method for checking the pump? (other than just visually checking for leaks)

good idea about the cap, but forgot to mention I've already replaced it!, had that problem once before with a Golf

also removed the pressure cap this morning when the engine was nice and hot, no excessive pressure in the system and no build up of pressure even after a further 10 mins hard driving (some threads suggest that high pressure can be a sign of a combustion chamber to coolant leak). So hopefully not that!

 

[enda1]

If there was no pressure build up in the coolant system after 10mins then you definetly have a leak as these systems are designed to operature under pressure as this raises the boiling point of the coolant.
You might want to check you have no cracks or pin holes in the rubber coolant pipes. I had this problem and with the engine idling there was no obvious leak but when I got someone to rev the engine hard and the pressure increased I was able to see a jet of coolant coming out of one of the main coolant pipes, it was spraying onto the block and then evaporating so there was no obvious puddles under the car

 

[Broken Byzan]

if you are using the right coolant, you will see a pink crusty bit from where the leak is coming from if it is external. I am sure if it were the heater matrix, soggy carpets would have shown up by now

 

[John@ECM-TECH]

on my Golf after about 3 months of loosing water you could see the water pump pully actually wobbling, this is when I changed it, the garage said "oh, yes they are desgined to loose water when worn"

Most people change the waterupmp in the audi's when they do the cam belt tho.

 

[Layerz]

My problem matches yours exactly, it has slowed down since it got cooler.

What ****** me off is I asked for the waterpump to be replaced at the cam belt change but I was told it did not need doing, and it prolly started around then.

Outa interest where is the waterpump on a 1.9 tdi?

 

[adbett]

not yet had to take much apart on the engine yet (that might be about to change!) but I think the water pump is at the front of the engine towards the bottom where there are several coolant hoses coming in and out - same side as the expansion tank.

 

[SonicDeathmonkey]

Mine is doing exactly the same and I get my pump changed each time th belts are done, it's only 50 quid.

I am due for the belts in 8K, so will see if it helps...

 

[Layerz]

Very interest to see what this is, as a friend swear blind it is head gasket but I feel otherwise.