coolant leak but dont know where water is leaking :(

[Tomm]

Hey guys

Need some help
my 06 gt tdi has has had a coolant leak for a while. The coolant bottle goes right down every couple of weeks or so. I have put a cardboard under the car to find where the leak is but nothing drips.

Ive also had the following checks done by my friend

egr cooler valve inspected and tested
coolant system pressure test
radiator check
pipes checked if anythings leaking
basically wherever the water runs my mate has checked but cant find the problem.

What really worries me is if the water leak is in the engine :(

i dont know if i should go to the vw dealers?

what should i do ?

please help

thanks
Tom

[mortygttdi]

The bkd 140pd engine has a problem with heads going porous, its not all engines but its been seen more frequently now. 1 of 2 places the coolant goes

1) the coolant drops into the cylinders through small cracks in the head usual when stood overnight and burns off has steam when you start the car up.

2) the coolant goes through into the egr cooler at the back of the engine and drops into the exhaust and again just burns off has steam.

You would need to do a pressure test and leave it overnight to see any losses has a quick test will not show up.

[vRSAlex]

Even a pressure test doesn't always show where a leak is.  Generally on these the Egr cooler would be the issue. Its worth bypassing that as a test.

[Tomm]

The bkd 140pd engine has a problem with heads going porous, its not all engines but its been seen more frequently now. 1 of 2 places the coolant goes

1) the coolant drops into the cylinders through small cracks in the head usual when stood overnight and burns off has steam when you start the car up.

2) the coolant goes through into the egr cooler at the back of the engine and drops into the exhaust and again just burns off has steam.

You would need to do a pressure test and leave it overnight to see any losses has a quick test will not show up.

So if I was to do that what should I be doing alongside that to find the leak ?

[Tomm]

Even a pressure test doesn't always show where a leak is.  Generally on these the Egr cooler would be the issue. Its worth bypassing that as a test.

My mate took of the egr cooler valve and it looked fine, he also got it tested and it came back fine

[mortygttdi]

Has Alex says bypass the cooler at the back not the EGR valve at the front, its easy to do but you'll need quite a bit of stuff removing to get to the pipes at the back of the engine.

[Tomm]

guys the egr valve that is behind the engine is the one that my mate inspected and got tested by our local radiator specialist. Who told us it was perfectly fine. Really dont know what to do :(

think i might just have to take it to dealers :(

[Andy]

as mentioned its possible it might be a porous head

[Tomm]

as mentioned its possible it might be a porous head

is that a big job to repair? what is the best way to know if its a porous head?

thanks

[Andy]

as mentioned its possible it might be a porous head

is that a big job to repair? what is the best way to know if its a porous head?

thanks

it is a big job as the cylinder head has to be removed and sent away to see if there is any cracks in it...Check the other possibilities first

[mortygttdi]

Could also be a damaged head gasket?? When Darkside Development took the head off mine to replace it the head gasket had gone between cylinder 2 & 3 you could see where the cylinders where wet wet with coolant.

[swedishfireball]

Can you run some dye through the coolant system? At least you may spot a dried residue as if it is leaking when everything is hot/expanded then it could be burning off almost as soon as it leaks.

Could be water pump seal/impellor or believe it or not the thermostat. Mine eas losing 100ml a week due to a knackered thermostat which turned out to be very awkward to diag due to only happening when warmed up and the seal expanding.

Good luck and I hope it's one of the easier/less costly issues.

[jason_rmh]

Just a thought...
I replaced the radiator on my brothers mk5 a few weeks back and that had a few leaks that weren't noticeable when it was on the car.
There were small pin hole size leaks in the rad core on the front side that you can't see as the bumper is in the way.
Also a leak from the lower rad pipe, bottom right side as you look at the car, replaced the o ring inside the plastic connector to sort that.

May not be your issue, but worth mentioning.

Jas

[Tomm]

thanks foe all the help. The radiator has been inspected and looks ok :S
i spoke to darkside and told me i should remove the egr cooler and see if that helps. Is their any down falls to doing that? i was planning to remove the egr cooler and replace it with a pipe and let the car run for a while to see if it sorts the problem. Should i do anything else alongside that?

[Andy]

if your removing the cooler then you may as well remove the egr as well