Oh No, It's BS (Again)

[husker boxster]

It was almost 5 yrs ago Sydney was diagnosed with Bore Scoring. Spent a lot of money ($28K) and time (almost 1 yr) on a rebuild with new Nikasil cylinders. Was supposed to solve the problem. Here's a link:

https://986forum.com/forums/performance-technical-chat/80281-its-bs-4.html

Fast fwd to mid-Jan and I start to hear a ticking sound during our annual winter cold snap. That's not good, as that's generally the starting signal of bore scoring. Keep an eye on oil consumption. She's now starting to drink a bit and the ticking is getting louder. Took her to SLM and they scoped her. Here's what they found in the #4 cyl.



Crap. Why did this happen?

SLM did some calling to see if there might be someone interested in doing some goodwill exploring but to no avail. The shop who did the rebuild has been sold and I think the mechanic / owner who did the rebuild has retired. Jake Raby is busy with other projects. No shops want to look at a rebuilt engine. Not many options.

Talked to SLM today about having L&N do the rebuild. They're taking steps in that direction.
The saga / nightmare continues...

[Smallblock454]

Damn…

Maybe i would go with steel sleeves next time.

[husker boxster]

Originally Posted by Smallblock454

Damn…

Maybe i would go with steel sleeves next time.

Steel dissipates heat at different rates (slower) than aluminum, so your engine runs hotter. You'll also have potential trouble with head gaskets. This isn't an issue when they're used in race engines since those are rebuilt more often than a street engine.

But if I'm having to rebuild every 4 yrs, maybe I have a race engine.

I would just like to know if it was something I did or if there was an error made assembling last time. The #6 cyl was good and that's the one that always fails.

[Qingdao]

Originally Posted by husker boxster

SLM did some calling to see if there might be someone interested in doing some goodwill exploring but to no avail. The shop who did the rebuild has been sold and I think the mechanic / owner who did the rebuild has retired. Jake Raby is busy with other projects. No shops want to look at a rebuilt engine. Not many options.

Talked to SLM today about having L&N do the rebuild. They're taking steps in that direction.
The saga / nightmare continues...

I am going to be picking up another 986 project car. I won't need the M96 you can have it for free if you come get it. I usually send the OE engines to the scrap yard.

[Smallblock454]

Originally Posted by husker boxster

Steel dissipates heat at different rates (slower) than aluminum, so your engine runs hotter. You'll also have potential trouble with head gaskets. This isn't an issue when they're used in race engines since those are rebuilt more often than a street engine.

But if I'm having to rebuild every 4 yrs, maybe I have a race engine.

I would just like to know if it was something I did or if there was an error made assembling last time. The #6 cyl was good and that's the one that always fails.

Yes, i know that steel has a different expansion coefficient that aluminium. But it seems to work. Over here in Germany we have different engine builders that are specializes in that topic for M9x6 and Mx7 engines. It works. But there are a lot of things to take into consideration. Gaskets is only one.

A full engine rebuild every 4 years is definitely not the way to go.

I would check if the piston ring clearance was OK and if they were mounted in the right direction. Also i would check if the cylinders are really round over the whole length. The oil supply for the oil spray nozzle for that cylinder might also have caused a problem. And of course you have to check the overall piston clearance.

[husker boxster]

UPDATE

SLM, my go-to independent shop, has been doing some research on potential options. As mentioned before, options were very limited. A new one is L&N advertises a swap option on their website where you send them your short block and they send an already rebuilt engine back. You'd lose your original serial numbered engine, but at this point who cares? However, they don't have any engines on the shelf to swap, so that option is out.

After striking out repeatedly, SLM came up with this proposal: they'll pull the engine, tear it down, send the halves to L&N for new sleeves, and then rebuild the engine when the halves return. Alex, one of the co-owners, and his dad rebuilt a 997 turbo engine so they've done that type of work before. I'm excited about this option. Not sure the plan is to replace the sleeves with the same sized ones (leaving the displacement at 3.8) or if they have to bump it to 4.0. I'm fine with either.

We're finalizing details and getting me on their schedule, but that's the direction.

Qingdao - thank you for your offer. Not sure if an M96 block would work instead of my M97, but you can do what you want with it.