Overheating mystery

[BK544E34]

94 530i. Has built motor. Irrelevant for this issue...


Car was not warming up so I replaced the thermostat and the waterpump (it was leaking too) Now the car won't bleed and overheats. The car has had stop leak in it prior to my ownership. Can blow through the heater core, no problem.

Car temp gauge will climb when giving gas and then will come back down with RPMs. Car has been bled with BMW Special tool vacuum bleeder, a Snap-on vacuum bleeder and has also sat with a spill free funnel and ran until it has warmed up. The heater is still blowing cold.

Any ideas where I should go next?

[Aleksey]

94 530i. Has built motor. Irrelevant for this issue...


Car was not warming up so I replaced the thermostat and the waterpump (it was leaking too) Now the car won't bleed and overheats. The car has had stop leak in it prior to my ownership. Can blow through the heater core, no problem.

Car temp gauge will climb when giving gas and then will come back down with RPMs. Car has been bled with BMW Special tool vacuum bleeder, a Snap-on vacuum bleeder and has also sat with a spill free funnel and ran until it has warmed up. The heater is still blowing cold.

Any ideas where I should go next?

Check / replace coolant temp sensor in the rear of intake manifold and one on passenger side of radiator.

Also if this issue is happening right after you build your motor... have somebody else open up and check it after checking it with vacuume gauge for proper Hg which will tell you if something is wrong right away.

[BK544E34]

The motor has 76k and counting. Compression is good and leak down is <10% on all 8 cylinders.

Will check the temp sensors, but the lack of heat leads me to believe that it would be an air pocket somewhere.

[FLG]

I usually drill one or two (small 1/8 ) holes in the metal sides on the thermostat. This makes the bleeding process MUCH easier.

[xxx-Lost-Soul-xxx]

Ever had the climate control on at Full heat and drive around like that for a while?

[BK544E34]

I usually drill one or two (small 1/8 ) holes in the metal sides on the thermostat. This makes the bleeding process MUCH easier.

I will try this... Still is doing the same thing. Having the heater on blast and driving around will still overheat the vehicle.

[Aleksey]

I usually drill one or two (small 1/8 ) holes in the metal sides on the thermostat. This makes the bleeding process MUCH easier.

? The car is self bleeding.

OP when you fill up the coolant, start the car and run it then take out the small line that goes to top left side (driver) of radiator until bubble free coolant is flowing.

[FLG]

The holes help to bleed the car so you aren't waiting for the thermostat to open.

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[Aleksey]

The holes help to bleed the car so you aren't waiting for the thermostat to open.

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You can use the method I described above, no need to drill anything.

[Jean]

Yep, these v8 systems are pretty much self bleeding.