1991 BMW 525i (OVERHEATING) HELP

[BeeMaa Blues]

Hi there I have just had the water pump and thermostat replaced because the pump had, had it. A few weeks before this I had the fan belts and Pulleys done. Now since then it has been Overheating could this be because of the work that has been done on it or some other reason? PLEASE HELP

[jeffreyb4me]

IF the waterpump impeller actually broke off [a orignal type plastic one], that and the t-stat should have fixed it. IF however the waterpump was replaced only due to leaking, and you'd driven the car too long and too hot you may have damaged the engine [head gasket/warpage].

Make SURE the shop has the system COMPLETELY bled [no air in the system], this can be difficult on M50/E34's due to the heater valve/pump location.

This may not be much help, but some more info from you if you have it would assist in further.

[BeeMaa Blues]

I just done the newspaper test on the fan and could stop it from spinning while the engine was running could this be the problem?

[jeffreyb4me]

That's a fairly good test. Another and maybe the best test is with the engine fully warmed up [hot], shut it off. If the fan spins for more than about 1.5 sec's. AND the center of the radiator is HOT to the touch, the Fan Clutch is bad. This will only effect engine temp. at idle and around town [stop & go] cuasing it to run very warm to hot.......jeff b.

[crash8168]

Nearly every m50 i take down after being overheated with any serious miles on it has had a cracked head.

[BeeMaa Blues]

Thanks for all your help ... But theres more Okay so I leave it idling for the first start of the day for 10 minutes, Within that 10 minutes the temperature is hot it has hit the (red area) so I turn it off I can hear water bubbling in the radiator bottle ...and after it has cooled down there is no water in the bottle .... where did it go? Any answers for this would really help... Also is a compression test the only way I can tell the head is cracked or is there other ways ... thankyou

[crash8168]

compression test will not tell you if the head is cracked. remove plugs, pressurize cooling system, leave overnight, crank with plugs out looking for coolant to spray out of cylinders.

[jeffreyb4me]

I agree with 'crash8168', but there are times when even this won't pinpoint the source, usually M50's and they do crackin some odd places, I've seen up to 8 in one cyl. head.....if it's not hitting the ground, it's going out the tailpipe.

[BeeMaa Blues]

Thanks for all the help ..Everyone... I will try that tomorrow...Crash... OK would the car be running rough? Because its running fine it just overheats... and when I turn the in car heater on the needle moves down to the 3 1/4 mark and stays there instead of the red area... the heater is also blowing cold air in the hot position.. Is that symptoms for something ? ...I know I should take it to a specialist, but do you know how much they charge here... I could buy a whole new car for that price.....Thanks Once Again

[jeffreyb4me]

Most likely, In your case, the heater is blowing cold air because of an air pocket, THE SYSTEM ISN'T BLED PROPERLY.

The engine won't necessarily run rough but may if the internal leak is bad enough

You MAY NOT have a cracked head but it's a real possiblity.

DO THE BASICS FIRST ! properly bleed the system.

You'll SAVE money with Reputable Indedependent. I rerepair BMW's everyday for people who've tried to "save money" at 'Igor's We Fix It All' shops, sometimes spending $$$$ for a $$ repair. Talk to some BMW owners in your area, there's uaually at least one shop where they know your car and are honest.

If you don't have one, buy a manual.

[BeeMaa Blues]

So whats causing water to spew out the reservoir when I turn the car off after it has been warmed up?

[jeffreyb4me]

Are you opening the rad. cap hot?? These caps have a release pressure rated @ 2bar which is rather high.....if it's releasing and is secure it soounds like a bad cap or ludicrous system pressure, i.e. blown hwad gasket...........

[4-Door Flunky]

The most important fact you've given us is that even after the car has been warmed up, you get cold air out of the heater vents. That means that no water is circulating through your heater core...or your radiator, probably.
If your car has already overheated, even once, then you've probably got other problems.
The needle for my temperature guage would start creeping up if I was stuck in traffic, and then then temp would go down as soon as the car was moving. That's when I knew it was time to replace my fan clutch. I didn't bother with the newspaper test.
Good luck...but I suspect you're screwed. BMWs will last an incredibly long time, if properly maintained, but you probably waited too long.
Flunky

[server_bmw]

Beemaa blues...
Infact, the same thing happened to me...
I had to replace my additional water pump...(the one by the fuse box)...because one day i was driving up I-85 and coolant suddenly spewed everywhere on the windshield... i stopped along the way to discover that the additional water pump heads had broken off and the hoses where no longer connected...the temp gauge ran red and I had to call my sis to pick me up...
Anyway, I had the pump replaced (fairly easy) and cranked the engine - letting it run for around 10 minutes. However, it still ran hot - all the way to the warning point. So i checked the reservoir and saw there was no coolant... I thought this was the problem but after filling her up a day later got the same results. So i had to call in the big guns(given my limited knowlege on the affair) on which after examination, told me the heads were cracked... oh boy!!!! I stronly agree with jeff... but first i think you should completely bleed the system for it may save you a ton of $$$$....
thanks and godspeed