TDi coolant loss

Zardoz

Active Member
Sep 6, 2016
525
214
North West
Sorry folks I keep posting bits in the What have you done to your car today thread about this and should have started my own thread long ago.

So my TDi has been loosing coolant in varying amounts over the last few months. Recent culprits have been a split hose (replaced) knackered radiator (replaced) and I’ve also changed parts to rule other bits out, first the coolant reservoir valve cap and then whole new reservoir itself. This has stopped the amount lost (from refilling every day!to every week) but it’s still not right.

Currently I’m getting the coolant alarm going off, wait for temp to drop, open the cap and WHOOSH it fill back up.

All this time the engine has never overheated stayed at 90

Just now I’ve noticed something new... had heater on driving home and noticed it blew cool air when stood in traffic/idle. As soon as I set off again it was face melting.

Any ideas what this could be pointing to?
 

chriswales6

Active Member
Mar 2, 2016
294
47
Sounds like poor circulation, possibly airlocks or maybe the water pump failing.

Have you checked the return flow to the header tank?
 
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Zardoz

Active Member
Sep 6, 2016
525
214
North West
I’ve watched the flow when the cars been idling and it seems right. I’ve not took the cap off to take a look when the engines hot though.

It’s due a timing belt change so I’d get the water pump done too.

In the meantime is there a way to bleed the coolant system of air pockets to rule that out?
 

chriswales6

Active Member
Mar 2, 2016
294
47
The return flow should increase with engine revs, there's videos on you tube showing what it should look like.

Sorry don't have much knowledge on bleeding the coolant. Thankfully my 03 Leon hasn't needed it yet, again you tube maybe able to help.
 
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