Help! Changed thermostat and housing, still overheats - BMW Forum

BlueKnight · 06-15-2009, 08:45 PM

After the plastic housing blew wide open, I switched to a metal one.
I replaced the thermostat as well.

BTW: When she overheated, I was off the road < 60 seconds

The car now overheats, within 1 minute.
What can this be/ faulty thermostat?
No water in oil Vice Versa

witeshark · 06-15-2009, 10:24 PM

Maybe a thermostat stuck closed. Do you know the water pump is good?

BlueKnight · 06-16-2009, 12:03 AM

Thanks White.
After posting, I wondered if that noise was the water pump. hmmm
I heard a high pitched noise coming from that area, I thought it may have been the belts.
Is there any way of checking it?

witeshark · 06-16-2009, 12:05 AM

There is, but personally I'd take that to a pro. But testing the thermostat is easy, Google it. That narrows things a bit!

marti5 · 06-16-2009, 06:19 AM

Pour some water over the belts, start up if they squeal they are loose.

Cas · 07-18-2009, 02:43 AM

You can check the pump by the reservior tank,remove the cap before starting the engine(making sure it is not under pressure,hissing when just starting to unscrew),start the engine and run till it gets hot,give it a bit of throttle and you should get a flow of water from the return pipe just under the rim of the expansion tank cap.
I just had to change my water pump about 4 months ago,not a nice job,but the pump only cost just over £30,i would'nt like to hazard a guess at what a garage wuold charge though.hope it helps.

thaman420@live.ca · 07-22-2009, 10:54 AM

Quote:

Originally Posted by Cas

You can check the pump by the reservior tank,remove the cap before starting the engine(making sure it is not under pressure,hissing when just starting to unscrew),start the engine and run till it gets hot,give it a bit of throttle and you should get a flow of water from the return pipe just under the rim of the expansion tank cap.
I just had to change my water pump about 4 months ago,not a nice job,but the pump only cost just over £30,i would'nt like to hazard a guess at what a garage wuold charge though.hope it helps.

i'm going true the same troubles and would like some info on how u did remove the old water pump , yesterday i removed my radiator to chek it out seems pretty damaged but i dont know then i looked at the termostat it was working fine so now im thinking water pump.

DonJ · 07-22-2009, 12:24 PM

On some cars there is a bleed valve on the thermostat housing. It is used to bleed air bubbles out of the system. You might have an air bubble that is preventing the coolant from getting to the engine. A while back I had an '81 528 that required me to add coolant once in a while. If an air bubble developed in the system, it would start to overheat. But once I opend the bleeder valve and burped the air out - the temp would drop back down to where it should be.

thaman420@live.ca · 07-22-2009, 03:03 PM

Quote:

Originally Posted by DonJ

On some cars there is a bleed valve on the thermostat housing. It is used to bleed air bubbles out of the system. You might have an air bubble that is preventing the coolant from getting to the engine. A while back I had an '81 528 that required me to add coolant once in a while. If an air bubble developed in the system, it would start to overheat. But once I opend the bleeder valve and burped the air out - the temp would drop back down to where it should be.

all try that has soon as i get a new radiator > anyone?

emiliomax · 07-28-2009, 09:17 PM

also, some models have the bleed screw on the expansion tank itself.

FoxNova · 07-29-2009, 01:08 PM

God this reminds me of my last car. My thermostats was stuck and car overheated all the time. I replaced it and it was fine until my radiator started leaking. One day I went outside and there was a puddle under my car. Turned out I had pin sized holes in it so I replaced the radiator and all was ok after that

Hope it doesn't get that bad for you. Good luck!

AlpineSixAndSeven · 07-29-2009, 03:33 PM

How many miles are on the pump in it? might be worth changing as matinaqce since your in there...

Cas · 07-31-2009, 03:00 AM

Ok Thaman, What i had to do was remove the fan from the pump assembly to remove the radiator,it gives a bit moreroom to work if you remove the pipes and hoses at the front,top of the engine,air box,loosen the pulley belt,not remove,(if you do remove,draw a diagram of how the belt came off),you can get to the tensioner from the passenger side of the car,move the belt away from the pump and them undo the pump bolts.I had to give the pump a bit of a tap with the rubber handle of a hammer,in case the pump is ok.
the impeller on the pump will be plastic if it is the original,bmw changed this to metal,then composite,original had design faults.
I was lucky with mine as when i removed it from the block the impeller fell into 4 or 5 bits which could have been floating around in my engine.
Its not really that big a job,just compared to say ford/vauxhall,which i can change in about an hour. hope it helps thaman.
By the way,if you are a bit strapped for cash,the pump itself will be ok,just the impeller will be trashed,i'n sure you can buy a replacement impeller,make a bit of money back reconing the pump.