530i expansion tank float stick too high

[B234R]

Well, yesterday I picked up my 2001 530i from the workshop, they replaced the water pump, the thermostat and a radiator hose (as a caution, they worked well but I bought the car a few months ago). Of course they put new coolant.

This afternoon, with the car completely cold, I checked the coolant level. The float stick was way too high, I thought the workshop filled that stupid opaque expansion tank (thanks BMW!) up too much, so I pulled out a bit of coolant with a syringe and a small hose but I extracted almost a quarter of a liter and the stick didn´t went down...if I push it down with my finger the stick drops, but as soon as I remove my finger the stick goes up again.

I think I´ve taken out enough coolant (see the picture) to see that stick lower but it remains the same height...anybody has any idea why this happens? I´ve read threads about broken float sticks living in the bottom of the expansion tank, but this is strange...the radiator was replaced by the former owner in May, but I don´t know if the expansion tank is new or old.

Thanks!

20181204_175157 (Grande).jpg 20181204_175209 (Grande).jpg

[lucas999]

I would try taking more coolant out, just to see if there is a point where the stick starts to go down. It seems that the reservoir might simply be way overfilled. After removing enough coolant, the stick should start to go down. Another possibility is that the cooling system may not be bled properly, and an air bubble could make it seem like the system is way overfilled when it isn't in reality.

The coolant should be far from the top of the expansion tank, hence the 'expansion' function. Best of luck!

[BimmerBreaker]

Start it for a bit to circulate, check the level again

[bigMphan]

Yeah, I'd be careful about that. With cooling systems being the Achilles Heel of our era of BMW the last thing you need is higher than normal pressures. I'd get it up and running, turn up the interior heat to 110% and if the stick doesn't come to normal siphon out coolant until that stick sinks in. You don't get to know how much overfilled it is. Any bit too much is too much IMHO.

If you're sure it's correctly bled and burped suck some out, go for a drive, let it cool and start from square one again.

[JimLev]

Check it in the morning when the engine is cold. If the stick is still high take more coolant out.
The tank should be 1/2 full when cold.

[crazy4trains]

You NEED to remove some more coolant. If the bobber is moving freely and still standing above the rim of the expansion tank there is too much coolant in there. Not enough room for expansion means increased coolant system pressures followed by broken bits and pieces.

[B234R]

Yes, if I look to the float stick it could seem there is too much coolant, but look at the picture...the stick is about 3,5 cm above the top of the neck of the tank, but that plastic inside the tank isn´t covered by the coolant. Could somebody take a look to his expansion tank and tell me if, with the stick in the correct height (level with the neck), that plastic is submerged in coolant?

20181204_175209 (Grande).jpg

Thanks a lot!

[TheAngryBear]

Normally mine “looks” empty when the float is at the correct height.
Remove some more coolant


2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1

[geargrinder]

^^^ Appreciate the caution B234R but yes nothing looks wrong... the tank does look "pretty empty" from above when its at the right point.

[crazy4trains]

Your answer is in post #6.

[B234R]

I´ve taken out some coolant, almost half a liter...and now the float is at level with the tank neck. I´ve driven about 40 km in heavy traffic and the temperature gauge was right in the middle, so no worries. I´ll be checking the coolant now and then, through.
Bad habit of many mechanics: overfill with oil, coolant, etc..

Thanks a lot!

[JimLev]

Make sure you only check it when the engine is COLD.

[ross1]

Yes, a bit overfull. Put the cap back on and forget it.

[effduration]

..... Could somebody take a look
20181204_175209 (Grande).jpg

Thanks a lot!

You're not running the required BMW "blue" coolant ?

[BimmrMeUpSnotty]

I’ve run the green stuff for a couple years on my old 530, never had an issue. But I did switch back to the blue BMW stuff before I sold the car. You just have to do a full flush of the system so that you don’t mix the two. I now run nothing but the BMW coolant in all my other cars, failure rates are all the same.

[crazy4trains]

Yes, a bit overfull. Put the cap back on and forget it.

Not the best advice for the e39.