4.4 Cooling System
 

Hey Guys,

My brother owns a 1999 540i with the sport package built 11/98. It has 133k.

He recently replaced all hoses (6 or 7), sensors, water pump, thermostat, expansion tank, bleeder screw and the little cap that it sits inside, etc. He did not replace the radiator or anything in the accumulator area.

He did some other work with the power steering hoses and when He was done He took it to the Stealership. This was His first time working on a car and when he started the car he blew off the upper hose coming off the radiator going to the water pump and thought he had really screwed up. But it was because he didn't get it fully connected to the water pump. The dealership looked at his work ran the car for a few hours and gave him a pass. They said he didn't have the connector on all the way.

He drove about 1000 miles with no issues and one day in the morning the "check coolant level" light comes on.

Here is what he has been doing for the past couple of weeks now. He takes the cap off the expansion tank and the level indicator is all the way down, He then turn the bleeder screw open and can hear some air hiss out and usually around the same time there is a click in the engine area. (bad thermostat??)

Once the expansion tank cap is off and the bleeder screw open the level indicator starts to rise and stops at the max amount of fluid. He puts the expansion tank cap back on, tighten the bleeder screw and get back in the car. The "check coolant level" is then gone until the next day. Or about 8 hours has to pass without driving and when he get back into the car the light will come on. But not all the time.

The "check coolant level" light has even skipped a day or two from coming on. It has never come on while he was driving. The light only comes on when it hasn't been driven in awhile.

Thanks guys

This is the same motor as the 4.4 X5, does anybody have any experience or suggestions as to what I should look for?

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