2008 x5 4.8 cylinder head crack!

[LA08X5]

This one is strange.

I have a 2008 X5 with 64k miles. There is a small hairline crack on the left cylinder head. The car has not overheated and drives fine, but the crack seeps oil after the engine is turned off. It took forever for my indy mechanic to find the crack, because it's not visible with the naked eye and it does not seem to leak when the engine is running. The oil begins seeping about 30 seconds after the engine is turned off. My Indy mechanic thinks it's a manufacturer defect from when the head was forged.

A side note... Just before the warranty was up last year, the BMW dealer replaced a leaking valve cover gasket on the same head... Then this summer, after the warranty was up, my Indy said that same valve cover was leaking again. I took it back to the dealer and after some wrangling, I got them to redo the valve cover gasket again under a repair warranty... but they also replaced the timing cover seals which cost me another $1000!

Now we discover this hairline crack in the cylinder head the dealer had worked on twice.

I've had no problems with over heating and there is no coolant leaking into the head...only oil slowing seeping out after the engine is turned off.

This is going to cost thousands to fix!

It's back at the dealer now and I'm wondering if this crack could have been caused by them?

So my question is: when replacing the valve and timing cover gaskets is there something the mechanic may have done to cause the crack?

ie: over torquing bolts or tightening in the wrong order.

I'm trying to learn as much as I can about what can cause this sort of thing before the dealer tells me it's not their problem.

please see attached pics

[LA08X5]

Thoughts...Anyone?

[A B Able Truck]

It's odd that a crack would leak when cold/engine off. I would attach a rag or something above the "crack" to verify that the oil is actually coming from that crack. I would assume the oil is just following it from above. Is the "crack" in a bolt passage?

[LA08X5]

AB Able... that's the really strange part about this. I'm 99% positive oil isn't seeping down, when I watched it happen, it appeared to come from the middle of the crack and spread outward. My indy Mechanic figures it must be in an area of the head where there's little oil pressure and it "seeps" when draining down. As far as being near a bolt passage, I think that is possible. I can't verify right now, because the car is still at the dealership, but If you look at the close up pic... to the left of the crack is the timing cover (which the dealer also worked on before). It looks like it's possible there is a bolt right there holding the timing cover to the head. But I can't tell for sure.
Maybe someone who's familiar with the engine setup can verify?

[A B Able Truck]

2008 4.8 - is that still the N62TU?

[LA08X5]

not completely sure. I've seen N62B48 online

[LA08X5]

actually, after some research, I believe it is the TU

[A B Able Truck]

There are 3 oil check valves towards the front of each head. (Supply, Intake, Exhaust > VANOS) They have O-ring seals - It's possible that under pressure they seal - heat also expands the seal. When it cools - the seal retracts and oil seeps. **Just a thought**

[ard]

1. Recognize that the dealer is going to go to bat for...the dealer. They will not say "yeah, we may have caused that" nor "that may have been the leak from the get go"

2. See if you can convince them to go to bat for you with BMWNA. If the dealer were to opine that 'the defect was likely present when the initial warranty work was done, but not recognized due to the rare nature", maybe BMW will pick up the tab.

3. If BMW isnt paying for it, pull the car out of there. Have a good shop weld the crack and re-machine as required. The dealer will just replace parts.

GL

A

[e30cabrio]

Sorry. I hope it works out well.