E39 540i Coolant Leak Under Inlet Manifold

[Mack10 3]

Hi guys

I've been losing coolant at about 250ml per fortnight for a few months without being able to find where it was going... I finally spotted a little bit of coolant at the rear of the engine under the inlet manifold. From looking at diagrams I think it'd probably one of the two pipes that run under there from the water pump.

Does anyone here have experience with this? Do these pipes crack or is it likely just one of the orings that's leaking?

Cheers

Edited August 25, 2015 by Mack10

[B.M.W Ltd 950]

It'll be the pipes or the valley plate. Also check the hoses going up to the throttle body

[Mack10 3]

Ok I'll have a look around the throttle body. What's involved if it's the valley plate? Is that just another gasket?

Cheers

[B.M.W Ltd 950]

The manifold needs to come off and the valley plate seal is a part of the plate. It's a bit involved to do and other parts may need replacing at the same time ie: water pump, pipes seals, thermostat, manifold gaskets, injector seals, PCV valve while your in there

[Mack10 3]

Thanks Glenn, waterpump and thermostat are done. Maybe I'll do the PCV diaphragm while I'm in there then.

[B.M.W Ltd 950]

I'd pressure test it first to determine the exact position of the leak before stripping though. Half the job is diagnosing the actual fault first.

[Guest cortez]

Heck ! 250mm is along drip......!

[Mack10 3]

Heck ! 250mm is along drip......!

[B.M.W Ltd 950]

Heck ! 250mm is along drip......!

Long drips have often been terminal... try Google