View Full Version : Adding coolant to expansion tank

08-09-2005, 12:57 PM
Just a stupid question...

When I got car back from dealer after doing the coolant flush.

I noticed the low coolant level warning came on and waited until the next morning to top up to the "level" mark.

I just opened the cap when I added and did not open the bleed screw. Now I am getting the low coolant level warning again... could it be that there is an air bubble in the system and should I be opening the bleed screw when I add coolant to cold engine?



08-09-2005, 01:32 PM
I think the sensor for coolant is in the resevoir (not sure for E39), do you find that you constantly are filling it? you might have a leak.

08-09-2005, 01:37 PM
thanks for the reply Gamite,

the sensor at the bottom of the expansion tank and to date I have not filled it, other than that initial time at dealership. In fact, my recent inspection with engine stone cold indicated the coolant level to be where I last left it. No indication of a leak either.. My intial thaught was a failed coolant level sensor.

Since I do a lot of driving between Hamilton and TO, I did not want to get stranded on the 407

08-09-2005, 05:00 PM
Here's the thing. You don't need to fill the expansion tank, and you don't need to open the bleeder screw to top it up. If you want to bleed it, run it how, and slowly open the bleeder screw.

One thing I did notice though after replacing my rad is that I did also receive a low coolant warning. If your rad, and exp. tank are intact, check the hoses that go from the block to the heater core in the firewall. One of my hoses had a small tear that was causing a slow leak. The OBD will detect a pressure loss and throw a low coolant level. The hoses are on the driver side of the block around 12 inches below the cabin filter.

Give it a shot.

08-11-2005, 10:21 AM
it takews several days , several trips to bleed coolant properly after it was changed. I ended up adding little by little after every drive and openin the bleeding screw to let the air out for 5 days.
I had low coolant light to come up untill the the system was bleeded completely.