Can anyone help with an overheating M30?

[Alyman]

Hi folks

Can anyone help me out with fixing my girlfiend's old man's E32 M30 3.5?

The car is overheating when stationary or in slow moving traffic.

The rocker cover and the top radiator hose get incredibly hot when the car is running, but the bottom right hose stays cold - maybe that's normal, but seems a bit strange to me. No sign of coolant/oil mayo under the rocker cover.

Things changed so far:

Thermostat (brand new one)
Fan and viscous clutch assembly (from a known to be good engine)
Coolant (seems to be bled fine, when the bleed screw on top of the TS housing is opened, just coolant comes out).

Is there an easy way of checking the water pump? Or is it worth looking at the thin pipe that runs up to the expansion pipe first, I've heard they can clog up and cause overheating?

Thanks for any info!

[Gwynleym10]

Obviously it overheating in traffic would suggest the fan clutch. But you say you go it from a known good car. Did you personally see the car stuck in traffic? Has it been off in storage for a while, even a month or storage incorrectly could change it from being ok / worthless.

My other thoughts are, have you de gunked the cooling system and flushed it with a hose? How is the radiator, take it out and have a look. This might be dead and you can't really tell when it is in the car.

My old m10 (m30s are a m10s and a half) used to pressurise the cooling system with exhaust gases. It was worse in traffic. It could be this, and that is the begining of a head going. There was never any mayo / coolant loss.

[Alyman]

The fan clutch was from an engine that's been in storage for quite a while, but it's always been upright on a pallet.

How good a guide is letting the engine run til it's hot then switching off and trying to move the fan by hand? According to haynes, it should be tougher to move. Can't say I noticed much of a difference, should it be quite obvious?

The radiator was in excellent nick when fitted about 6 months ago, looked almost new front and back.

I really hope it's not the head gasket!

[Gwynleym10]

Hmm

The best way to test a viscous it to get the engine hot and put roll of newspaper in the fan, it should shread the paper easily.

[Andy335Touring]

How hot is it getting ?

Do you get good continus(sp?) heat out of your heater ? (posible air lock if not)

When warm your bottom hose shoudn't be cold, it should be fairly hot to the touch.(themostat not opening if cold bottom hose)

[stranter]

I'd bet money of the fan. A new one is £30 from GSF and is a thirty minute job to fit IF its a pain! The newspaper test works, also you should be able to actually hear the fan working when hot.

Stewart

[Alyman]

How hot is it getting ?
When warm your bottom hose shoudn't be cold, it should be fairly hot to the touch.(themostat not opening if cold bottom hose)

Well, I reckon this'll be it then. I wasn't there when he fitted the new one, is there any way it could have been fitted incorrectly? Would it go in the wrong way round?

Cheers

[Andy335Touring]

Well, I reckon this'll be it then. I wasn't there when he fitted the new one, is there any way it could have been fitted incorrectly? Would it go in the wrong way round?

Could be the wrong way, it's only 4 x 10mm bolts to take the 'stat housing off to check, if you look carefully on the 'stat there's an arrow that should be pointing upwards when installed(depending on who makes the 'stat ?), not sure what it's for though ?

The 'stat housing doesn't have a gasket so just clean it up and use a thin smear of instant gasket type stuff on it.

This is how it's supposed to look below

[Alyman]

Thanks for that Andy, I'll check it out and see if that's the problem.

[Andy335Touring]

Also check the 'stat in some boiling water to make sure it opens ?