N62 Valve Seals Update

[robertsen]

Oh sorry - thanks for reminding me about a follow up Bulk! Good luck to you! Also, I would never pay someone for something like this. The cost was so high because they would have taken the heads off the car assuming the guides needed replaced. I was going to leave the heads in place, only having to deal with the cams and saving some money not having to replace head gaskets etc. Some might disagree with doing it this way but if the guides are also bad at 100k miles this brings up a lot of concerns about this motor period!

[TiAgX5]

Originally Posted by robertsen

I have a bently manual but it is absolutely zero help.

Bentley really dropped the ball on the head/valvetrain info for the N62 engine. They have about 20 pages of info on the M62 and nothing for the N62. Good to hear the issue was resolved with a different oil.

[SlickGT1]

Bentley has been a massive failure for the 4.8is. The only thing of value in there was the torque specs for the trans pan. Other than that, the entire car is a hit or miss in there, including the electrical diagrams. Epic fail.

[Roadkill]

I have read about this valve guide failure on early N62's, especially on the 7 series. Those early motors also have to contend with the dreaded coolant return pipe leak in the middle of the motor. Roughly a $3K-$4K fix with stock parts.

[jbond007]

I'll post my reply to a PM I got:

I started by using a product called AutoRx to see if the car's valve covers were just sludged up after first replacing the CCV valves to no change in my smoke issue. I only had 78,000 miles when this all started. Warm up, then still and idle - say at a stoplight, take off and smoke out the back...

Well, It seemed to have worked great. When I had to take off the valve cover (more on that later) everything was sparkling clean! I actually switched to "dino" oil for that 4000 mile cleaning phase as that is the best combo for the AutoRX product. Then I went back to Royal Purple synthetic for the "rinse" and/on.

But I'm still smoking so I took my car to my indie mechanic after unsuccessfully fixing the smoking problem by cleaning the valve cover labyrinth/oil separation channels. It made no difference. My indie mechanic still wanted to replace the valve covers out-right so... $$$. He said that was the next logical step. He thought they had fixed the issue, but when they got her all back together and let her idle.... smoke. They called their friends at the dealership and found that 4.8is' across the board are having this issue. If it's under warranty the stealer is replacing both the heads entirely! They say the valve guides and seals are wearing prematurely.

Sooo. Instead of $10,000 for 2 heads, he says he can just do the valve guides and seals for around $3000. Not a happy camper.

[SlickGT1]

Shiiiiit. Have you considered doing it yourself? You might be a much happier camper.

[PropellerHead]

Originally Posted by dinan e39

I have read about this valve guide failure on early N62's, especially on the 7 series. Those early motors also have to contend with the dreaded coolant return pipe leak in the middle of the motor. Roughly a $3K-$4K fix with stock parts.

You'll find the coolant problem throughout the life of the N62. Up through the E70 as discussed in this thread. It's so common in fact that All German Auto made a fix and sells it through many outlets.

[dkl9323]

Robertsen, was it the Bardahl product that ended up doing the trick?

Thanks!

[alpinasam]

Originally Posted by robertsen

Sorry for not putting on an update sooner! I actually never did the repair. My biggest issue was passing smog here in California. I ended up using 10/30 (vs. 5/30) oil and an additive. The smoking disappeared completely and it passed smog. It was never a performance issue just smog; my minor leaks went away also. I am personally going to continue to use this approach and change the oil more frequently.

As far as the repair goes, the biggest challenge for me was finding a proper manual with specs etc. I have a bently manual but it is absolutely zero help. I posted on their site but no help was suggested. I also paid for a 24 hr subscription to bmwtechinfo.com and it was no help either. I figured about 1000.00 us dollars including the required special tools.

Good luck to anyone with this engine! Also if anyone has any sources for a manual I would appreciate info.

My 4.8is has just started billowing blue smoke when taking off after idling at lights etc only since last service. I'm guessing the previous owner might have switched to a heavier oil & an additive. Which additive did you use?

If we keep the car I'm going to throw an SC at it down the track so don't mid doing a head rebuild at that point, but right now i'm in the process of restoring 4 other cars, so would prefer to use a bandaid in the interim