Ricardo Vega

Hey guys, can anyone recommend a trustworthy shop to have block checked and possibly honed for my 1987 S4 block? I live in El Paso which is close to both places.

Thanks
RV

jeff spahn

honestly you should check with Greg at Precision Motorworks in Anaheim. Not many shops in the country can work on a 928 block in the proper manner.

Mrmerlin

no one should be honing a 928 block unless the original cylinders have been removed

GregBBRD

I've heard the "back story" on this.

You should just find another block. You are not going to be able to reapply that grey muck back onto the original block.

All part of the learning curve....don't feel bad. I once had a 356 engine case cleaned by a local machine shop (circa 1968). All that came out of the tank was the steel head stud that they had attached a wire to in order to pull the case out of the tank.

SwayBar

What happened, what is the story?

SeanR

Curious also. What necessitated the need to machine the block?

Ricardo Vega

That spot at at bottom was cleaned off with just a rag.



Well story goes like this, and I don’t think anyone else knows because I’m just reaching you guys about it now. Unless someone else knows something I don’t.
Anyways, as I was removing engine apart a friend who is a mechanic recommended that I use Zep industrial cleaner which ended up leaving a finish that’s very rough and block is a bit darker too.
Have talked Rob Edwards and he recommended that I get the Sunnen tool and clean up residue left inside cylinders.
Is it possible that the aluminum is physically damaged from a soap/detergent? I find it hard to believe that molecules of alloy and/or Alusil has come off or been damaged?
My cylinders are very good! No scratches or dings in walls at all. I’ll see if I can post some pics in this post.

Bigfoot928

Is the cleaner purple? Several commercial cleaners that you could get at auto part stores could ruin wheels and blocks that are aluminum.

Mrmerlin

you can buy a jar of the bore paste get a hone and get some felt sheet cut it and place it over each stone,
polish the bores and see what you get, the paste will remove some aluminum and leave behind silicon.

BUT the block itself looks pretty bad from a corrosive cleaning chemical

Ricardo Vega

Yeah, the color of fluid purple. So what makes my block, “damaged” based on looks? I didn’t think about this before but I have a few friends that metallurgical that I can maybe ask questions about.

how deep is the silicone in these blocks and is it only inside the cylinder walls? And how will I know that my cylinder is good? Just based on smoothness?

By the way, the white spots on block can be removed with a damp or dry rag. But the color of block is what change.

Thank you all for feedback.

RV

The Forgotten On

The upper half of the block is Reynolds 390 IIRC and is entirely AlUSiL, the bottom half of the block is just aluminum.

You could hone the cylinders and go up to the next tolerance group or bore size, from 100mm to 100.5mm etc.

I will be less expensive to just get another engine unfortunately.

jeff spahn

Ooohhhhh. Time for a new engine....and friend (maybe, maybe not) At least now you have a cool coffee table bottom. Spend some time polishing it up, get a glass cover and you have a table.

hacker-pschorr

Assuming the aluminum is in deed ruined, a coffee table would be a real waste. It could still be bored out for a stroker or Nakisil coated.

Coffee table's should be reserved for cracked blocks beyond all possible repair options.

GregBBRD

Yes. Certainly can be bored and honed.

What about the crankshaft bearing bores, the oil pump surface, the cylinder deck surfaces?

If it was a GTS block or a super low mileage collector car where matching numbers mattered....it could be repaired. However, I do not believe it is either of these.

928 International 1/2 price sale in December this year?

GregBBRD

ZEP industrial cleaner will remove anodizing from aluminum almost instantly, and "etch" the surface of the aluminum very quickly.

It's like putting a nail in a bottle of coke....

I was told that the cleaning fluid had a grey sludge in it, after you soaked the block overnight.

If thus is true, that grey sludge is aluminum that was etched from the surfaces. The result is that the silicon is now completely exposed. Even if the bores and all the other surfaces still measure good, the silicon will be unsupported due to the lack of surrounding aluminum and will most likely be "sheared off" by any sort of load or friction (piston rings.)

Find another good block with pistons, or a block with the same tolerance group as the one you have.

BTW...."home rebuilding" of 32 valve 928 engines very rarely has "good" results. There's so many "tricks" to these engines, I could literally write a book on how to do this job. Home rebuilders (and even professional mechanics not familiar with these engines) do not have the access to the knowledge required to do this job.

For example, I'm working on a GT engine which had the cylinder heads "done" and "ready to install".
If the engine is going to have my name on it, EVERY fiber of my being requires me to disassemble these heads and inspect them. They were an incredible mess. Whatever machine shop.performed the work....they should have never touched them. It's literally going to cost me 2X what heads normally cost me to do, in order to get them into a condition that is up to my (or Porsche's) standards.

Forget, for a moment, about all the little "tricks" to building one of these engines....just think about the above:

How is the "home mechanic" or "unknowing professional" going to build a good engine if the basic pieces that need "freshening" are not done correctly?

Over 50% of what I do is redoing work from other shops/people. While it is expensive to do this stuff once.....it is really expensive the 2nd or 3rd time through!

I got another GT in this week. In 15 years, the owner has spent $65,000 on this car (not by me.) No paint, no interior work, engine has not been rebuilt. The intake and valve covers have the original finish.....falling off. (We're looking for that $65K....has to be stashed in a cubby hole, inside the cat, somewhere.)

The car doesn't run. The main front wiring harness looks like someone "disected" it with a chain saw. It has a 14 pin wiring harness on it that is an absolute fricking joke...wires that aren't the correct colors, in the incorrect gauge...wrapped in sime sort of electrical tape, without any heat shielding down where the loom passes along the exhaust, just some shrink fit.

More crap from one of the 928 suppliers!

The injection harness got "rebuilt", by the same people. Terrific! The boot that goes through the firewall is cut in half!!!! How do they expect to be able to keep water/fumes out of the interior?

The bill on that stuff? $2400!

$2400 that I'm going to remove, walk over to the trash can, and toss into that trash can.

Choose wisely, people.