M52 2.8 overheating problem - bleeding air help

[mrLEE30]

my 528 (1996) has a stationary overheating problem, changed the fan clutch and same deal, but on the road it drops immediately down to half, and also drops if i am stationary and rev it 2-3K.

so reckon it could be an airlock, can anyone tell me how to bleed these bleeding things!! found a plastic bleed screw on the hose connector near to top of engine (at the front) and i am guessing that is how i bleed it.

Is it same as M20 for technique? i.e warm up engine, turn on heater, and bleed air till water comes out. do i leave the expansion bottle cap on during the bleeding or does it not matter?

cheers all.


(oh yeah any other suggestions as to the overheating i will deal with after the bleeding issue!!) one step at a time!!!


mr lee

(apprentice post whore)

[Ant]

almost defo a duff plastic impellered waterpump dude, they slip on the shaft and can cause the exact issues you're reporting, for the cost of the part I'd change it ASAP, but insisit on a metal bladed unit as a replacement.

for bleeding, yes, same as M20, maginally easier to bleed

I normally let them run to temp, heater coming out hot, and water circulationg in the exp tank, then top up, rev and hold @ 2K ish, then close the bleed screw and exp tank cap, job jobbed.

HTH

ps, whats the weather like ??

[Andyboy]

Whilst you're doing the pump - take the thermostat out and drill a 4mm hole in the outer ring. Refit the 'stat so the hole is at the top. This makes bleeding them about 100 times easier.

[DanThe]

My engine does the same, not really overheating though, when stationary even with the fan on full chat I need to lift the revs to about 2k to get the temp down. It has a BMW metal bladed water pump so I havnt changed it but is this likely to slip as you say Ant?

Whilst you're doing the pump - take the thermostat out and drill a 4mm hole in the outer ring. Refit the 'stat so the hole is at the top. This makes bleeding them about 100 times easier.

Andy, only thing with this is that warm up takes about 5 times longer. I tried it with mine and ruined a brand new stat

It does help bleeding but I wouldnt do it again

[mrLEE30]

cheers all, we bled it last night and it seems ok, was quite a bit of air in there, but will do waterpump as a precaution, cheers all.

ant it is getting into our winter here in Bahrain, during the day it is a chilly 35C and in the evenings and even colder 26C, i can get the roof down in my cabby however but i need to wear a teeshirt it night! BRRRRRRR!! It will stay like this now till january where the temp may drop as low as 10C at night, but by day 15-20, then march - may same as now then the summer comes and my cabby gets put away as temps in the day easily reach in excess of 50C in the sun!!

Basically we are opposite of you lot, we hate summer and love the winter, UK is the opposite!!

cheers for the advise lads

mrlee

[Geeman]

Had the same problem with another E38 728i that was in my possession. Was the stupid plastic impeller on the water pump!!! Changed to the metal variant and problem solved.