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2000 528i overheating

1K views 12 replies 2 participants last post by  tredburn08 
#1 ·
Hey guys, I want to one, say hello as this is my first time on the forums, and two I apologize for the lengthy post as I am desperate for help. So, a while back I bought a this 528i hoping to make a good car out of it. The guy told me it had an overheating problem and didn't have a clue why. When I returned to the garage with the car, I noticed the corner of the radiator was cracked, so it immediately received a new radiator and thermostat.

Shortly after this I find that the car is still overheating, check cylinder pressure and can't build over 80 pounds of compression in cylinder #1. So I take the head apart find my blown head gasket issue, and simultaneously discover the problem with the m52tu aluminum engine. The big sert kit was installed and I now have 130+ compression in all cylinders.

I filled the coolant and took it out for a drive. Temperature got up to 215 according to my scanner and then dropped to 180 and continued to fluctuate between the two. Job well done....until the next day.

Next day I notice the temperature is starting to rise and hits the 3/4 mark on the temp gauge, then goes back down to normal. After a few minutes, it hits the 3/4 mark again, but this time continues to climb, so I shut it down.

I am at my end with this thing guys. Does anyone have any suggestions for me? Huge thanks in advance.
 
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#3 ·
Yes, bled it at the screw by the thermostat. I did have to top the tan off this morning with coolant, so I checked the oil just in case, but couldn't find anything strange about the oil. Is it possible for an air pocket to be trapped within the engine somewhere?

That would be my only reasoning for having to fill more coolant, because there are no visible leas that I can see and no puddles on the ground.
 
#4 · (Edited)
yes the air pocket has killed alot of bmw engines... its best to let the car sit and warm up to build a little pressure in the system, then open the bleeder screw, also, i like to have someone rev it to 1800 or so a few times to kind of burp the system if that males sense...it always gets out just a little more air...

also if you filled it and closed it but did not refill when theh thermostat opened, the level drops quite a bit when the thermostat opens....

i usually fill it ...

let it warm up

thermostat opens and the water level drops...

i then refill it then close the radiator cap...

let it build a little pressure, youll feel the upper hose get hot ..

then open the bleeder screw till no air bubbles come out..

close the bleeder...

then have someonein the driver seat

open the bleedder again and have them blip the accelerator to about 1800 a few times
more air almost always comes out... the water level will be slightly low but if its not overheating then leave it until the car cools off and you can safely open radiator cap again without loosing coolant and refill it...

beyond that either the thermostat is sticking closed or the waterpump is failing ...also be sure your fan is working properly

does yours have a bleeder screw on the expansion tank as well...mine has the one like you speak of on the tstat housing too..but ive never used it...only the one on the expansion tank just to the front of the radiator cap with a + cut into it...that lets the air out of the radiator as well
 
#6 · (Edited)
also i forgot to add...if air continues to come out of the bleeder , theres a very high possibility that the headgasket is blown again....unfortunately it doesnt not take a whole lot of extra heat to blow the gasket and warp a head ...if it gets 3/4 of the way over, im just guessing its in 280f or highrer range... the dash gauge is pretty crappy on our cars...i know on mine the temperature can fluctuate between 180F to almost 255F and the gauge never moves from the center ... so if its ok now, i would never let it go that hot again, once you see that the needle on the gauge is moving past the dead center , its a safe bet to assume something is wrong... shut it down immediately and let it cool down

you may have to buy and expansion tank...the bleeder screw has a small slot cut in it to allow the air to escape...

im hoping its just an airbubble
 
#8 ·
So much to my dismay, I believe I have found the issue. I sat under the hood for a bit with the car running and as soon as the thermostat opened up, I got coolant leaking out of the top edge of the housing. Its torqued down to specs....so im starting to worry that there may be a crack in that water passage :(
 
#10 ·
take a look, it may just be a piece of debris in there./..this happened to me on the valve cover seal on my m3 a lonig time ago...took me forever to figure out it was seeping out from under the valve cover seal because it had a chunk of old gasket still stuck under it
 
#11 ·
I looked into it further and it is a crack in the head running perpendicular to the housing. I'm going to drain the system, clean it extensively and hope that jb weld will hold up to the pressure of the coolant system. To my understanding it is only like a 15# system? If so my hopes are high. I can't imagine having to buy a new head and go through all that work again :/
 
#12 ·
well that sucks...do you think it was already like that or it happened the second time it overheated...if its still good...you will have to have it welded ..but if its cracked generally the head is no good..

im sorry to hear it
 
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