Overheating here, blown head gasket? - BMW Forum

brandoncrrll · 08-15-2011, 02:01 AM

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HI guys i just bought this 98 528i automatic. The previous owner said the water pump and thermostat were just replaced and said it had some overheating problems, but just needed to be topped off with fluid and should be fine. I topped off the exp. tank and 5 minutes into my drive the temp started to sore.
When i got it towed back home checked it out.
-The oil doesnt appear to be milky
-Cant really see and contaminents in coolant.
-The car will not overheat at idle, only when getting up to speed
-The top hose is very hot, the bottom is cool
- When i leave the exp tank cap and bleeder off, the bleeder will let alot of gas out and i cant maintain a level in the exp. tank. I will add some fluid then it will overflow, and then the level will drop way down...
I fear this is a blown head gasket. Maybe the shop screwed up on the thermostat job? i sure hope so. I think the prev owner may be hiding something from me. ON the paper it said he went in for a coolant leak and then they replaced the pump and thermostat, and then maybe the overheating problem arised?... thanks for any suggestions theyre much appreciated!

Additionally, there is no visiable white smoke coming out the exhaust, atleast when its running at idle in my garage.
The check engine light is on ofcouse, i tried doing the diagnosis where you press the accelerater pedal 5 times but the light just stayed on and didnt do anything. Does that not work for this year?

jimmythepie · 08-15-2011, 03:47 AM

Air lock,search threads for solution.

brettski · 08-15-2011, 06:25 AM

How much coolant have you put into it so far?
Is the level still dropping or has it stabilised? It may be that they didn't purge the air out of it when they changed the water pump and thermostat.
It could be that the water pump that they installed is a cheap one that doesn't have the impeller fastened to the shaft properly. (Some impellers expand when hot and the shaft simply spins freely).
When its idling, what goes on with regards to the top and bottom hoses?

brandoncrrll · 08-15-2011, 10:37 AM

COuldnt find any good threads on air lock..... But i cannot maintain a level in the resovior. when i top it off, and then the engine warms, alot of gas spews out of the vent which pushes all the coolant out, and then the level will drop back down to low.

When starting it up from cold and just letting it idle, once the engine get ups to temp the top hose will suddenley get very hot and the bottom will stay cool. But the engine (atleast accorfing to the temp gauge) does not go a hair past midway when just ideling.

jimmythepie · 08-15-2011, 11:36 AM

mmmmm,wait till Dabsy appears he knows everything.

brandoncrrll · 08-15-2011, 11:58 AM

OK i just let the car idle for like 30 minutes with the bleeder cracked and air just keeeeeps bubbeling out, and im not really adding too much water except for the stuff thats spilling out of the bleeders i think. But both hoses are warm now... NOt a good sign i suppose

brandoncrrll · 08-15-2011, 02:26 PM

I think someone needs to just tell me what i dont want to hear, a leaking head gasket

brandoncrrll · 08-17-2011, 07:51 PM

My god, am i supposed to have an electric fan in this car?? i found a 4 wired plug thats just laying there that looks like it would plug into an electric fan up front!

Jack Dabsy · 08-18-2011, 04:03 PM

THX Jimmy...
Bubbling IS NOT GOOD... You could have a air-line crack from a cylinder to the water-jacket causing carbon-dioxide to enter the coolant and create a geezer, or boiling effect !
I have mentioned on your other post that the M52 2.8 does have electric fans in front of the rad, but test the mechanical clutch fan too !!
HTH