N53 - inlet side oil leak

[Ian Geary]

Afternoon,

3 hours into removing the inlet manifold from my E61 525i.

This is to cure the sickly oil smell of a small leak being fried by the exhaust.

I have previously sealed the crank cover, but could see a leak under the inlet manifold.

Common wisdom it's the oil filter housing (ofh) gasket.

Now the manifold has been removed (hidden bolt and wiring loom took me nearly an hour to figure out!) I can see a fair bit of oil under each inlet.

But I don't think the ofh gasket looks that bad. The oil would have to have travelled a lot to cover the whole face of the block I think.

(Some of the oil might be old, from when the crank cover was leaking)

Question: can anyone suggest any other sources of oil on this side?

I'm thinking pvc or egr leaking oil into manifold, and then leaking out of each manifold again onto the block?

I will be replacing inlet manifold gaskets along with ofh gasket.

Thanks

Ian

Pics

Looking at ofh


Looking at block


Close up



(Side bet: it's 2pm Sunday. I need this car working at 8am Monday. Who thinks it will be back in one piece by then? )

[bmwmike]

Did you get it back together?

Could the oil have run out of the inlet when you removed it? Otherwise maybe it's from higher up toward the front and has run back..

[Ian Geary]

Afternoon

yes, I got it back together by about 7 pm-ish, but after all that, I chickened out of replacing the oil filter housing gasket, as it really needed coolant and oil draining down to avoid making a complete mess of the aux belt.

It was about minus 4 outside, getting dark, and everything I'd removed had frost on it, so I had had enough by then.


I don't recall seeing any oil leaking from the inlet manifold when I removed it. Although the inlet system inner surface is coated with oil (ie your finger would get marked rubbing it, as expected with a crank vent), it did not have enough oil to collect in a pool.

I did spend time cleaning the block of oil. I've done about 60 miles since, and I did peer at the car block today. I will add photos below, but basically the oil is back.


It definitely is not coming from the crank cover, nor from the inlet manifold (now with new gaskets too)

If I had to say anything, it probably looks like it's weeping out of the cylinder head gasket, on the basis that's the red gasket visible below the inlet manifold.

Yet the car isn't experiencing any "normal" HG failure symptoms - i.e. no overheating, loss of power etc.


I think I need to clean it up again, do the oil filter housing gasket, and then monitor. The inlet will definitely be quicker second time round, but it still a fiddly job.


Ian

[Ian Geary]

Pics from two days of driving after the cleanup. It's not gushing out, but is a healthy weep.

Frankly, it it was all from the oil filter housing, I struggle to see how it would make its way round the contours of the block to the cylinders further back...


Overview



Cylinder 1




Cylinder 3





Cylinder 4

[HJG]

Was the inside of the intake manifold oily? What about the valves?

[Ian Geary]

Hi

It sounds daft after removing the inlet, but i didn't really get a good look at the valves asy phone light wasn't bright enough.

There was definitely a film of oil around the inlets, and in the manifold, but not puddles of the stuff.

Looking through the pics I took, this photo of an inlet (after I'd removed the manifold) shows a small trace of oil. So perhaps this suggests oil is gathering at the gasket, and leaking through?

So this would point at the pcv system perhaps? Or excessive blow by.

[HJG]

There's a chance the CCV system has frozen in the cold weather combined with short journeys. There's plenty of info on this online.

[bmwmike]

When my n53 ccv failed it sucked oil around into the inlet, and it pooled because I took out the top disa valve and had a look inside.

That said, I never had a trace of oil anywhere on the outside of the engine.

What's the front of the engine like, around the oil housing, heat exchanger etc? With new gaskets etc I can't see it being from the inlet as it would run like a dog too. I suggested originally it might have poured out when you lifted the IM away, but can't be an active leak

[I-am-the-reverend]

Oil filter housing gasket. It drips down and runs along the side of the engine.

I had this exact thing on my 523i E60 2006.

No need to drain coolant if you're careful, just remove the filter element to allow oil to drain back into the engine. An old towel under the heat exchanger will catch the cupful of coolant that escapes.

They use aluminium bolts that need to be replaced.

[Ian Geary]

Bump time.

I took off the inlet manifold (again) and replaced the oil filter housing gasket, using some sensor safe etc for food measure.

I also resealed the (new) inlet gaskets with a thin bead of rtv.

This stuff has worked perfectly when sealing my valve cover gasket.

After 30 or so miles, the oil is back, as before, running along the edge of the cylinder head gasket.


Question - what is this bolt? There seems to be oil welling up from beneath it


Thanks

Ian

[Ian Geary]

Well, the 5 series forum got it in under an hour. It is apparently a cylinder head bolt, and there are a few posts about them occasionally snapping.

Luckily, the front bolts don't take the pressure of the cylinders, and it's more the timing chain cover part.

So once i source a new bolt ($5 in the USA, but none to be had in the UK it seems) the inlet has to come off yet again.

And I should probably check the other bolts under the valve cover, which means a pita of removing and resealing it.


It is probable the oil filter housing gaskets were fine all along - this is the danger of diagnosis via internet I guess.


Ian