Coolant expansion tank leak

[BritishMattWorks]

Hi all, so yesterday I replaced the thermostat of my Z4 3.0si which went ok seems to have worked so far. I'm no expert but looks like something was missing in the middle of it (see image) which might explain why it never got warm when running.


I've now got 2 new issues one seems to be an airlock in the heater hoses that I thought I bled out yesterday.

But I also spotted that around the coolant expansion tank it seems to leak though can't quite tell if it's under the cap or hose connections on the back though probably worth changing both.

Has anyone does this job or can point me to a good video on it?

Also is there a tool that anyone recommends for refilling coolant that reduces getting air in the system? It was a pain trying to push the air through the hoses to get the heater working last night only to have it not work today, meaning I probably need to do it again. And I have done the electric pump bleed procedure but it didn't seem to clear that.

 

[smorris_12]

On they older engines, expansion tanks would occasionally leak from a seam which made it harder to diagnose.

I found the N52 bleed cycle to work well. You don't have the noise pointed down at all, do you? That'll make it struggle. And have you got the HVAC set to full hot?

 

[BritishMattWorks]

Yes was set to full hot, and nose was raised when I did it yesterday. I think I have a lot of air in system that needs to work though and not enough coolant, checked before I drove today and the coolant was low. Probably just need a few more cycles to get it through.