Saturday 9 August 2014

E60: Oil Leak Verdict.

More bad news for the 5 Series I'm afraid. Got it up on the ramps at work with five mechanics and as many torches to finally see where the bulk of the oil is coming from. In this post [] my attention was solidly on the turbo oil-feed and return pipes, but further investigation has revealed that no oil is dripping from them and if they are leaking then it is only a seep, which is eventually building up on the underneath of the pipes. The main oil leak it would seem is running down the front of the engine. Unable to see where though or trace where the oil is running from due to the belts and pulleys covering the front of the block so well, I tentatively assumed it was coming from the front main crank-seal - oh dear. It stands to reason that swirl-flap damage could have unbalanced the crank somewhat and caused the front main-seal to leak, but this theory is stopped by two factors - 1. If oil was leaking so badly from the front crank-seal, it would be hitting the pulley and have the trademark 'spray pattern' in a circle around the main-pulley, and 2. If swirl-flap damage had unbalanced the crank enough to let this much oil out, then the engine would be a bit more recalcitrant that is being!

Pressurised oil?

So where is the oil coming from? We blasted the entire front of engine with brake-cleaner and stood back to watch where the oil arrived from. Thankfully we watched it pool and run down from above the main-pulley. The other lads suggested the usual suspects - rocker-cover gasket or a loose oil-way at the front of the block, but there is no denying signs of fresh oil are present everywhere on the engine where there is a gasket or seal. This means the oil is being forced out of these joints somehow by pressure building up in the crankcase and would explain how oil that cannot be from the frontal leak has made its way onto things that are nowhere near it, i.e the turbo feed/return pipes. It also explains my other big problem - oil entering the air-inlet. The worst case scenario is the main turbo-seal dumping oil right inside it. This makes for both a lot of oil getting blown into the engine, but also gives a smoke-machine effect out the back, the latter of which I have no signs of as yet.

Smoky CCV [Crankcase-Ventilator]?

I removed the rubber-hose that recirculates the CCV (crankcase-vent) back into the turbo while the engine was warm and running. Thick oily smoke was billowing out of the CCV, which I duly replaced [eBay £35], though it did not affect the problem and holding a hand in front of the smoking pipe for a minute leaves an oily residue. It would appear the oil is getting into the air-inlet by condensing down the CCV recirc pipe into the turbo impeller. This is definitely not normal CCV behaviour and finally gives a sure sign off abnormal crankcase pressure. Finally, with the car on ramps and the underbody-protection fully off it became clear that oil was dripping pretty bad from the back of the engine and pretty much everywhere else, even the sump.


I started another thread on BMW Land [] and the torrent of 'I told you so' replies came in and backed up my fears about piston 6. The rings are stuck inside the piston and not making good compression. The lack of power isn't really being picked up under normal driving, but the blow-by is so bad that it's allowing combustion pressure straight into the crankcase, hence burnt oil and exhaust smoke pouring out of the CCV. You wouldn't think a swirl-flap bouncing round could cause the rings to do this, but check the picture below. Well, you live and learn. This weekend I will be stripping the sump off the car and then, of course, the head is coming back off, which means more new bolts and another new gasket, coming to about £120. Sadly, even BMW cannot tell me exactly which piston my engine has from neither my reg. or VIN, so I will have to pop it out the top of the block and identify it before ordering one as they're over £200, but this means the car is off the road at least another week. I managed 268.5 miles between engine rebuilds... 

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