Leaking coolant on '95 530

[Jon K]

Hey guys - have a '95 530i with alusil block that my sister daily drivers. Shes been losing coolant for the last couple months. I checked it out last night and it looks like its from the water pump/thermostat area but you know how its hard to tell on the V8s. It looks like her car has a black (and thus plastic) thermostat housing piece (so thats prob the leak.. maybe) but I figure if we're doing this we should replace the water pump, the t-stat, the housing, and all gaskets.

Is it common for these things to leak here? Going to replace it with a metal t-stat housing, a new t-stat, and all the gaskets I can think of.

What do I need/need to know?

Thanks peepz

[Ross]

The o-rigs on the pipe that runs beneath the intake to the water manifold at the rear between the heads.
you will be so happy to have a six after this.
http://www.realoem.com/bmw/showparts.do?model=HE13&mospid=47406&btnr=11_1246&hg=11&fg=35

[yaofeng]

It is probably a good idea to replace all four o-rings on the two coolant tubes when you do the water pump.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_540/DSC_2726.jpg

And if you are that far already, might as well do the valley pan.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_540/DSC_2741.jpg

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_540/DSC_2824.jpg

It's easy if you have the engine on the stand.
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_540/DSC_2833-1.jpg

[Jon K]

I saw a drop of water/coolant on the crank pulley below the t-stat housing and the water pump has some residue on it. Should I start with the water pump/tstat and see whats up? Why do need to do the valley pan gasket? How hard is the intake manifold to get off?

[yaofeng]

You're going to find two o-rings behind the water pump. Are you going to stop there?

Pulling the intake is not hard.

You don't need to touch the valley pan if it is dry. If you do, you can not simply replace the pan gasket. BMW no longer sells it. You need to buy a new pan. It has the gasket baked on.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_540/DSC_2818.jpg

[Jon K]

I dunno I was thinking of replacing the water pump and t-stat alone. The o-rings on the front side of the engine as well I suppose. Whats the point of that pan? I don't see how it does anything. I am not very well versed on BMW V8s. Why would it be wet, and what does it do?

[uscharalph]

How old are the hoses? while you're at it.

[yaofeng]

BMW must have its reasons to keep that part of the block on V8 in coolant jacket. Why would it be wet? If it has a gasket, it has the propensity to leak in time.

[Jon K]

My question was - is there coolant under that cover? I dont understand what it is - I dont do V8s traditionally.

[Tiger]

Mileage on that car would help... usually at about 100,000 miles that things starts to go... My radiator first went... then my water pump... then my thermostat housing. Thermostat housing is the primary suspect.

You can tell on water pump when you park with car downhill and engine running... you can see the drips with a flashlight.

[Paul in NZ]

I dunno I was thinking of replacing the water pump and t-stat alone. The o-rings on the front side of the engine as well I suppose. Whats the point of that pan? I don't see how it does anything. I am not very well versed on BMW V8s. Why would it be wet, and what does it do?

they are the valve covers arent they?

[Barney Paull-Edwards]

You're going to find two o-rings behind the water pump. Are you going to stop there?

Pulling the intake is not hard.

You don't need to touch the valley pan if it is dry. If you do, you can not simply replace the pan gasket. BMW no longer sells it. You need to buy a new pan. It has the gasket baked on.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_540/DSC_2818.jpg
Thats good ol` Sikaflex, $4 a tube with nozzle.

[Ross]

You stand a chance of disturbing the rear o-rings while doing the pump. they can be done w/o removing the intake.

[yaofeng]

Thats good ol` Sikaflex, $4 a tube with nozzle.


It came to my mind. Then I decided I wasn't going to dive in again for another 60k miles, perhaps more. Knowing how many times I screwed up DIY in the past even with kind replacement, the decision was easy.

[Ferret]

My question was - is there coolant under that cover? I dont understand what it is - I dont do V8s traditionally.

Yeah the V8 has a bath/galley that runs down the centre top of the block to cool the top edges of the pistons... quite common for the later M62s to spring leaks here past the 100k miles mark.

http://www.e38.org/intake/engine-24.jpg

[Jon K]

Thanks Ferret - jeez thats a strange thing - leave it to bmw!

Her had an alusil block put in, so I suspect all the seals and such are newer than the chassis, which has probably 140k or so. So the motor is probably at 40 - 50k miles which is water pump territory. I am replacing that stuff first and if I have to I'll go back in for the valley pan. All in all, this stuff isn't nearly as daunting as what I've done to my car - it should go well.