Overheating under load cool at idle

[Bimmer96]

So iv searched for hours and cant seem to find anything like this. I replaced my cracked degas tank and bled it a ton of times. I have heat with the coolant cap on all the way but to airlock after a little bit of running and start to overheat if i accelerate and no heat. i have the cap cracked a little for the time being so i can get to work and what not. It has a new water pump the previous owner had put on. Im a BMW tech and havent had a bmw or mini do this eaither. any help will be appreciated

 

[FASTLLS]

BMW tech ehh.. cool.. I was going to be one but decided I liked the lineman career better.

I would bet you have another cracked plastic cooling part somewhere and still getting air into the system..
Wait.. are you getting heat?

Check that your fan is running at full speed..

What year and engine?

 

[Bimmer96]

BMW tech ehh.. cool.. I was going to be one but decided I liked the lineman career better.

I would bet you have another cracked plastic cooling part somewhere and still getting air into the system..
Wait.. are you getting heat?

Check that your fan is running at full speed..

What year and engine?

Well i get heat for a little while befor it over heats then i crack the cap and back off the pressure and its cool again and no heat. but im running with the cap backed off a little and its running at normal but i have a little heat and none at idle. the fan is working fine. its a 2001 v8

 

[FASTLLS]

Check the cross over tube, feed (running by the head; it's plastic), coolant tree for cracks.. It's normal for these to crack and let air into the system..

 

[tireman]

fan pump or fan motor

i had the same problem in my 01V6. turned out my fan motor went bad. check out the actuator on the pump also, it may be failing. from what i understand you can take off the actuator and clean it. my fan pump would work correctly by pumping the fluid,,,the fan motor appeared to work normal while sitting still, but once on the road the fan motor would not do the high speed consistently.

when you turn on the heat, you are taking some of the heat out of the coolant system which helps cool it down.

 

[FASTLLS]

i had the same problem in my 01V6. turned out my fan motor went bad..

That's what I was thinking.. Kinda sounds more like a fan problem..

 

[Lincoln Jealous]

i had the same problem in my 01V6. turned out my fan motor went bad. check out the actuator on the pump also, it may be failing. from what i understand you can take off the actuator and clean it. my fan pump would work correctly by pumping the fluid,,,the fan motor appeared to work normal while sitting still, but once on the road the fan motor would not do the high speed consistently.

when you turn on the heat, you are taking some of the heat out of the coolant system which helps cool it down.

i had my actuator on the pump replaced before, caused an overheating problem, wasnt easy to diagnose or find