Coolant Level Float

[giraffophobic]

Hello again, recently I corrected a coolant leak issue on my 2006 3.0si by replacing the expansion tank and coolant level sensor, and verifying there were no further leaks with a pressure test. Today I checked my coolant level again, and the float was sitting at the very bottom of the tank, with no coolant visible.

I have been driving reasonably far distances in the couple weeks since the repairs, and have had no low coolant or overheating warnings appear on the dash. I checked the level after the engine was off for approximately 10 hours. Is this a normal/non-concerning occurrence, or something worth getting checked out?

I'm getting a leak down test for my head gasket on Friday

 

[Ewazix]

Did you re-fill and bleed the system per TIS? Unlike my M54 I think you need to activate the electric pump on your Si, otherwise it could just be the level settling.

 

[giraffophobic]

Did you re-fill and bleed the system per TIS? Unlike my M54 I think you need to activate the electric pump on your Si, otherwise it could just be the level settling.

Yes, the process of re-filling/bleeding was completed. I believe the mechanic took care of the pump activation while doing the bleeding. If the level is still settling, am I able to drive with the coolant level as-is? Or am I misinterpreting

Thank you for the response

 

[enuff_zed]

Did you re-fill and bleed the system per TIS? Unlike my M54 I think you need to activate the electric pump on your Si, otherwise it could just be the level settling.

Yes, the process of re-filling/bleeding was completed. I believe the mechanic took care of the pump activation while doing the bleeding. If the level is still settling, am I able to drive with the coolant level as-is? Or am I misinterpreting

Thank you for the response

I think you should be filling it back to the correct level and then monitoring it.
Hopefully it was just an airlock sorting itself out and it won't drop again. But I would be looking at all the hoses etc that you disturbed when you changed the expansion tank. It is possible a seal hasn't seated correctly. When I changed the tank on mine I renewed all the O-ring seals in the ends of the hoses, and the ones I removed were quite hard and flattened.
Top it up, run it until it is hot then pop the bonnet and see if you can see any leaks.

I'm just keeping my fingers crossed for you that it is not in any way related to your oil usage issue.

 

[giraffophobic]

Hello again, forgot to update this thread a few days ago. Leak down test results indicated no head gasket leak (phew) but what was discovered was a very difficult to spot crack on the underside of the upper radiator hose. The theory is that the small amount of coolant escaping (while the engine was running at operating temperature) was evaporating as it escaped, leaving very little trace in a difficult to access space. I believe an occasional contributor to this issue was the expansion tank cap not being tightened all the way after topping off the coolant ("just tight enough" was not tight enough), although I don't know for sure.

How the hose leak didn't make itself apparent during the pressure test of the cooling system is a different question...

Thank you all once again for your assistance!

 

[Ewazix]

That's a good result, micro-leaks can be tricky to find