N62 Engines

[Turbo_Bimmer]

Last weekend, I met a friend that I didn't see for a couple of years. He's a BMW tech. I told him I was selling
my E46 to get a N62 X5 (4.8is or 4.4i).
His reaction was like I anticipated. Requires lots of maintenance, etc, etc.
I told him I was ready to deal with all those problems, even transmission problems.

But, when he started talking about N62 engines getting replaced at a very high rate because of cylinders
getting oval toward the top, I became speechless.
BMW doesn't sell short blocks, only long blocks, at 20K retail... ouch!
He says that the M62 was not doing that and is more reliable, true??

I then asked him if those 'N' engines could be rebuilted, and he said no, well, BMW doesn't do it.
I read on this forum that someone had success inseting sleeves in one of those engines. Could that person tell
me if it was a custom job, of those sleeves/pistons are available through engine rebuilding shops?

If some BMW techs on this board or N62 owners read this, could you tell me if you have seen this wear pattern
on the N62, or they are isolated cases.


Lastly;
There is something he told me that could help N62 owners with idle problems. He told me that replacing the
intermediate levers, and shaft doesn't always solve the problem. They found that the valves were getting a lot
of deposit on them and were either sticking, or not closing properly. He says he now removes both heads,
disassemble completly, and clean / gring all the valves by hand + change the levers + shafts. It seems to solve
the problem.
I really wanted a N62 X5, but now I'm not sure if a M62 will be more bulletproof.

[JCL]

There aren't posts on here about oval cylinder bores, as I recall. What doesn't fit for me is that both the M62 and N62 use the same technology for the cylinder bores (aluminum blocks with Alusil). Not sure why one would be much different than the other.

Deposits on valves are often related to poor quality fuel, with insufficient additives to clean the deposits away.

There are lots of things that can break on an X5, and some maintenance and repairs will be required, but engine overhauls are not one of the things I would be worrying about.

[Weasel]

I've been a dealer tech for about 6 1/2 years and have yet to see any N62 engines come through with cylinder damage as described.... maybe those were severely overheated or something?

[Naz24]

The only issue i have had with my N62 is intermediate levers. Which honestly was no big deal in my opinion. But otherwise shes still running strong at 91k miles.

my transmission on the other hand.. luckily replaced under CPO warranty 8 months ago.

[Turbo_Bimmer]

Thanks for the feedbacks, it is good to hear that it is not a common problem.

I took a look on realoem, and to my surprise, I saw that oversized pistons were available for the N62. I always tought that an Alusil block couldn't be re-bored because it removes the coating on the cylinder walls. So why those pistons exist?

I'm still interrested to hear from the person who installed linings in a M/N62 block, please chime in.

[Weasel]

I know M5james has a sleeves M62 in an E38 7 series... that's probably who you're thinking of.

[sasquatch]

I worked at a local BMW dealer during college many years ago and recall seeing a high number of 740 and 540 cars come through requiring new engine blocks because of the the block/liner material. Don't recall the specifics but I think it had to do with a low (or maybe high) silicon content in the casting/liner. Something about the cylinder bores wore out due to the material used. Owners got a new engine block from BMW at no cost. The X5 wasn't out yet so I never saw those vehicles while working there.

[amacman]

I have data somewhere . I will post it here sometime ( may take a while to find time to look ) .
M60 V8 engines had NIKASIL cylinder walls which were destroyed by high sulphur content in fuel . EDIT - some engines still have Nikasil , some have Alusil depending on which country the vehicle was originally sent to .
maybe some early M62 `s were affected , maybe not .
some engines have ALUSIL blocks , no coating on the cylinders as the alloy is hard enough .
the data has all the info , when I can locate it .

EDIT - found it in minutes . had to make a PDF because file would not load otherwise .
had to delete page 24 because PDF was too large . no big deal , it was only starter motor info .

[sasquatch]

^^ that was the problem. I remember a good number of 740 and 540 equipped cars came through the shop and the only BMW tech made a killing off the work. He had it down to a science after the second or third engine replacement.

If I recall they only sent a short block. Don't remember if it came with new pistons and such.

But you could definitely tell which engines had the problem and which didn't. They tended to have less power and knocking noises.

[Weasel]

Yeah, the original M60 with nikasil... that problem had just cleared up when I started, so I didn't get to do any of those.