Cylinder leakdown higher after engine rebuild?

[Chanman1029]

A good read on the subject:
ttps://digitalmetrology.com/tutorials/plateauhoning/

https://www.aa1car.com/library/plateau_finish.htm

This hurts my head, I’m gonna have to read that like 5 times to comprehend it

[sapote]

A good read on the subject:
ttps://digitalmetrology.com/tutorials/plateauhoning/

https://www.aa1car.com/library/plateau_finish.htm

[sapote]

While I do agree with you, my fear is that the metal wear will only get worse, and further damage the cross hatching, which would then cause excessive oil burn.

I think I am going to drive it a little more, do oil changes more often and see how metal content in the oil improves or declines.

I don't know if the shop - Lang - had done any post machine work on the new honed cylinders or not. Depend on the honing process, the newly cut cross hatch lines have uneven height sharp peaks and they should be processed to have a plateau instead. To get the plateau, a nylon ,or other material, brush is rotating to change the peak to plateau and clean up the metal debris, then washed off. If not done, then the new rings would do the job of creating the plateaus but process also wears down the new ring edges, which is not good.
Hopefully after some more miles your rings will seal better than now.

[Chanman1029]

Some of the best advice I have gotten have not been from BMW know it all shops like VAC or Metric Mechanic. One was a dune buggy fabricator that had an in house engine builder. The other was a machine shop that did mostly aerospace work in Wichita, KS.

The machine shops in Houston mostly suck.

As far as your issue...I feel for you. You'll probably get better info from this forum than you'll get from most of the BMW "specialists".

I think I remember you mentioning that machinist in wichita, what all kind of work can they do? At some point I’d like to have my spare crank and block machined, it will need the journals re welded. Safe to say I’m searching for a new shop to send my future work to.

[oceansize]

You'll probably get better info from this forum than you'll get from most of the BMW "specialists".

These BMW "specialists" won't even come on a forum like this. Too proud and think they have it all figured out. Much more respect for shop owners like George Hill and occasionally Kaiv who come on these forums read, participate, and post. I'm sure there are other shop owners here as well and perhaps some who at least lurk. An expert is someone who has been burnt so many times they've developed a gut instinct for when they need to pause and reach out for help.

[bigjae46]

Some of the best advice I have gotten have not been from BMW know it all shops like VAC or Metric Mechanic. One was a dune buggy fabricator that had an in house engine builder. The other was a machine shop that did mostly aerospace work in Wichita, KS.

The machine shops in Houston mostly suck.

As far as your issue...I feel for you. You'll probably get better info from this forum than you'll get from most of the BMW "specialists".

[Chanman1029]

If it's not burning oil, and is running fine just run it. No reason to rebuild the engine if there are no real external symptoms

While I do agree with you, my fear is that the metal wear will only get worse, and further damage the cross hatching, which would then cause excessive oil burn.

I think I am going to drive it a little more, do oil changes more often and see how metal content in the oil improves or declines.

[Chanman1029]

Well, as a paying customer with a shared incentive and liability that’s kind of shitty.

it sounds like a crap situation all around. Sorry man. If it were me, I’d swap the motor for a known good, running motor then take apart the Lang bottom end and post your findings.

You’ll be able to get reliable measurements on the components and know where things went awry.

did he use his widened rod journals and bigger bearings for your bottom end?

Nope, we just polished the journals and used king bearings. Nothing special with the crank.

[chapmans]

If it's not burning oil, and is running fine just run it. No reason to rebuild the engine if there are no real external symptoms

[tlow98]

totally get what you are saying.

as for all the specs, I asked lang for the build sheet and he actually told me he would not give it to me, as it is “proprietary info”.

sounds kinda silly to me, but whatever

Well, as a paying customer with a shared incentive and liability that’s kind of shitty.

it sounds like a crap situation all around. Sorry man. If it were me, I’d swap the motor for a known good, running motor then take apart the Lang bottom end and post your findings.

You’ll be able to get reliable measurements on the components and know where things went awry.

did he use his widened rod journals and bigger bearings for your bottom end?

[Chanman1029]

What are the details of the build? What size bore/pistons, which bearings were used (main and rod), what fasteners, etc? Cylinder spacing, ring gaps, block and head deck amounts, material of pistons, etc

call out where anything is not stock.

ok, I just reread where you talked about not knowing the bore size. Here’s the issue, as the assembler you need to know all the intimate engjne details and be able to double check work before you assemble.

this is not fun to hear as you received the short block assembled, but by receiving it assembled you left someone else in charge of a QA/QC step you could no longer do.

this is prolly where the hard lesson is.

lang should have all of your specs written down. If they don’t, that’s their responsibility.

you should also have them and be able to verify

now, o know you paid money to remove that risk, but the compounding issue that there’s no way I’d warranty a part of a build if someone else had control over something I did not. This is the situation Lang is in.

it sucks for both of you. Shared assembly responsibility. It will always be a he said, she said

totally get what you are saying.

as for all the specs, I asked lang for the build sheet and he actually told me he would not give it to me, as it is “proprietary info”.

sounds kinda silly to me, but whatever

[tlow98]

What are the details of the build? What size bore/pistons, which bearings were used (main and rod), what fasteners, etc? Cylinder spacing, ring gaps, block and head deck amounts, material of pistons, etc

call out where anything is not stock.

ok, I just reread where you talked about not knowing the bore size. Here’s the issue, as the assembler you need to know all the intimate engjne details and be able to double check work before you assemble.

this is not fun to hear as you received the short block assembled, but by receiving it assembled you left someone else in charge of a QA/QC step you could no longer do.

this is prolly where the hard lesson is.

lang should have all of your specs written down. If they don’t, that’s their responsibility.

you should also have them and be able to verify

now, o know you paid money to remove that risk, but the compounding issue that there’s no way I’d warranty a part of a build if someone else had control over something I did not. This is the situation Lang is in.

it sucks for both of you. Shared assembly responsibility. It will always be a he said, she said

[Icecream]

Lang assembled the short block, I mated the block and head.

Got it, yeah they should own up to this if it materializes into a problem, can't believe there is no warranty. For now it sounds like it runs fine and no excessive oil burn so just enjoy it? Just for fun, have it dyno'd too.
For the torque plate, I think that's only necessary with a bore and a few shops (including lang) confirmed that.

[Chanman1029]

Catching up on this, did you reassemble or did lang?

Lang assembled the short block, I mated the block and head.

[Chanman1029]

piston looks like alot of non black buildup / deposits for a few thousand miles? is it burning oil? are you using any additives

No additives, and no oil consumption that I can tell. Granted I’ve only taken oil to 1300 miles on this recent oil interval.

what do you mean by VAC 2.0?