😀Hi,

Recently brought a 645ci .

Expansion tank full/empty level indicator was broken , but float was working.

Changed reservoir tank and now the coolant warning light intermittently comes  on , checked coolant and it is full.

Could it be faulty expansion tank or air lock?

Car is running fine and not overheating.

Welcome any ideas.

Regards

Neal

Afternoon Neal

When you changed the expansion tank did you move the level switch over from your old tank or did the new/replacement have one fitted?? 

I take it when you say level indicator you mean the rising flag under the main filler cap? That is just an "idiot" guide to help people know when it is full/empty by giving a visual reference 

The actual level switch is in the bottom of the tank with a small electrical plug, try unplugging it and replugging it in case there was some dirt on a connection.

Dave

Hi Dave,

Replacement tank came with flag, I will clean connector up and also check there is no air lock.

Thank-you for responding,

 

Regards

Neal

OK Neal

Was the replacement "shiny new" or used if it was used maybe the level switch has a fault. It's item 2 at the bottom of the drawing realoem gives the part number below.

17137553919

 

Hi Dave,

It was brand new and is a Bilstein.variant

Morning Neal

A Bilstien variant ? Is the tank the same as the one in the drawing and is the part number  17137542986 or different ?

Have you had the codes read and reset? which may clear it other wise I would still suspect the level sensor even brand new stuff can have a fault. if you still have the old tank try swapping the level sensor.

Dave