Significance of cyl wall coating

[iamsam]

So I started this thread to address a specific concern of mine regarding a specific incident, and also this thread can be a good source of technical info for anyone curious regarding cyl wall coating vs. sleeving etc, and why BMW chose to do that.

My specific scenario:

- pulled the heads off of an M62B44 NV
- one head bolt wouldn't come out of the head all the way due to interference w/ the cam
- that bolt dropped down as I lifted the head
- the weight of the head pressed the threads of the bolt into the cyl wall
- the threads ONLY damaged the cyl wall at the VERY top, ABOVE TCD where the rings stop

Will this be a problem, or can I clean up the area and proceed w/ the franken build?

The biggest problem I see is the small area w/ lack of coating. The only thing this area will see is the combustion chamber. Since the heads aren't coated w/ the same stuff, I assume this is ok?

Thanks guys

[nrubenstein]

If it's above where the rings run, you should be fine.

[iamsam]

If it's above where the rings run, you should be fine.

it is. The damage is enough to have created some particulate however, and could have even pushed a little material up past the head/headgasket plane, so it will need to be mildly filed or sanded so that the plane is flat.

Because of that, there will be a very tiny area where the head gasket isn't perfectly flush/concentric with the cylinder wall, and will overhang a few thousandths over the damage area. Again, this is only part of the combustion chamber, so I don't see how that can really be a problem.

[bmwmech1]

Take some pics... they'll help in the evaluation from all of us in the peanut gallery...

Garey

[iamsam]

Take some pics... they'll help in the evaluation from all of us in the peanut gallery...

Garey

Yep. I will do that if I make it to the junk yard today (tried pulling yesterday, jy closed before completed)

[JGood]

Bore it, sleeve it, boost it. That's the only reasonable option.

;)

[iamsam]

Bore it, sleeve it, boost it. That's the only reasonable option.

;)

that's the most unreasonable option. cost per benefit is massive. We covered this in another thread, where the cost to bore and sleeve could buy you an S62.

That said, a home brew twin screw on one of these beasts would be awesome.

[JGood]

that's the most unreasonable option. cost per benefit is massive. We covered this in another thread, where the cost to bore and sleeve could buy you an S62.

That said, a home brew twin screw on one of these beasts would be awesome.

Haha, I was just joking.

[iamsam]

Haha, I was just joking.

i know you were. ;)

I am just quite bummed about this little mishap and I am really hoping that it won't be a problem.