1.9Tdi losing coolant but we can't figure out how

**chrisgeary** · 11-01-2009,07:48 PM

A friend of mine has an R reg 1.9TDI B5 with about 100K on the clock. its losing coolant but only while running. It will alarm every few days (50 mile round trip commute daily) and require topping up.

The radiator and water pumps have been changed. The water pump had partially failed as a fin was missing. The system has been pressure tested and no leaks found. There are no leaks in the cabin. The heater works normally. There are no pools of water under the car. No signs of dripping or damp smells anywhere. The only odd thing is the downpipe from the coolant reservoir is cold when all others are warm. I checked my 1.8T and the downpipe is about as warm as the main coolant pipes. He's even used radweld and its still losing coolant. Its just disappearing.

Anyone had this before or could suggest what to look for next?

thx

Chris

**passat 130 tdi** · 11-01-2009,08:29 PM

with the engine hot, pop the bonnet and look for any steam vapours rising.

**adamss24** · 11-01-2009,08:31 PM

Blown head gasket or a porous head. Diesels are able to run with steam inside pistons so, when you take the head off, it will show where the gasket is blown as the head in that area will be very clean due to the steam.

**chrisgeary** · 12-01-2009,12:11 AM

Thank you both

**gujiguy** · 13-01-2009,01:14 AM

Hi,

I put radweld in the coolant and that worked a treat for me. I had the same problem as you, it will lose coolant every 50 miles.

Give it a try and see if it works.

**scotty33** · 13-01-2009,01:21 AM

If you take the top engine cover off, you can check the coolant pipes which bolt to the side of the head, these are plastic, with an O ring seal at the flange. Over time the flange warps and starts leaking.

**chrisgeary** · 13-01-2009,10:29 AM

Originally Posted by gujiguy

Hi,

I put radweld in the coolant and that worked a treat for me. I had the same problem as you, it will lose coolant every 50 miles.

Give it a try and see if it works.

Interesting, how much Radweld did you use?

Chris

**gujiguy** · 13-01-2009,12:10 PM

I bought a little bottle from halfords and poured everything in. I first poured the radweld and then put water in.

Its been 3 months now and havent had any problem till now.