The pictures speak for themselves. S3 with about 1500 miles since the manifolds were blasted and powder coated.

The engine is ruined. The pistons are done, the wrist pins no good. Awaiting the news on the heads, but I'm not holding my breath.

Look at the grey grit. It was everywhere.

I had hope the block could be saved for a stroker build. But, I don't think I will ever get it clean enough for that.


Abrasive material suspension every where

Where the block sat

 

Ouch. Was that one of yours?
Did the manifold at least tern out beautiful? JK
-Jason

 

O.M.G.
Cheers

 

happens too often... :-(

 

And the owner is a bit OCD in a good way. My hands never got dirty enough to wear gloves when I pulled the engine. That's a first.

He spent a lot of time cleaning the manifolds before assembly. There was no oil in the manifolds - bone dry.

The pipe to the number #3 was thick with grit.

Here's the condition of the pistons. They are rubish.


1-4 Left to Right

5-8 Left to Right

Notice it's 1 and 5 pistons that got polished the most.

Here's what the ring in #3 hole looks like.

#3 piston ring on top of brand new ring. Mind the gap.

 

What a waste of an engine !
Are none of the other blasting media options able to remove the paint without this risk?

 

Very sad. I put mine though my ultrasonic parts washer then through the dishwasher with no soap, but the 16v intake has way fewer nooks and crannies in which to trap blasting media.

 

so sad.
but now we look for peeling manifold on a 928 as a plus point ?!
Peter

 

There's a lot of takeaways here, some of which are pretty well known to the community, at this point. For me, this looks like a great example of a destructive feedback loop. If I had to guess, there was nowhere near as much media left behind as what's shown in the top pictures. Instead, what little bit of media was there kept producing more "grit" as parts were worn down. What makes this loop even worse is that some of what is produced is aluminum oxide which, at high enough a temperature, will convert over to the alpha phase, also known as sapphire. Sapphire/alpha alumina is a terrific abrasive, which then just makes this process even more destructive as it begins to accumulate in the engine. Even if the aluminum oxide that is produced doesn't make to the alpha phase, the other AlOx phases are plenty abrasive.

What a nightmare.

 

Any idea how many miles went on the car after the powder coating before it pooped out? Just curious.

 

What type of blast media was used? Condolences to the owner.

 

The rear of each plenum has a couple of very nice spots for accumulated abrasive material to hide. You basically have to get your hand in there to feel for it no matter how much time you've spent cleaning, In my case I found enough to ruin the engine AFTER I spent eight hours cleaning them and stopped seeing material at the bottom of the tub.

 

The owner thinks and I agree that the blast material was from the underside of the cam covers. He was able to pick out small chunks now.

 

Sad!!!

 

Yeah, sorry, but that's completely wrong.

Most of the damage occurred on the upper rings, the bores, and the pistons. The media entered through the intake, got into the combustion chambers and did all this damage. It stands the rings away, gets shot through the pil return holes to the wrist pins, destroying them. If you pull the intake valves on the cylinders that were sanded the worst, you will find severe stem wear. This occurs because the media sticks on the intake valves' stems, when they are open and is carried up into the guide when the valve closes.

....While there is a path to this area, from the oiling system, it is VERY difficult road to get there..and the oil filter has to become clogged and bypass internally to get into the oiling system.

The blasting debris gets trapped on top/bottom/sides of the velocity stacks in the plenums..in huge amounts. This occurs because of the considerable amount of oil in the plenums, which "traps" the media, in places that can not be reached by regular cleaning. Pressure washing, running them through the dish washer is a joke...the stuff is stuck where the spray can not reach. We even made a pressure washer nozzle that turns 120 degrees...and this would not remove the trapped media!

This media debris will still be trapped in places around the velocity stacks. If you figure out a way to get your fingers/some tool up and around these velocity stacks, you will feel it/get some out.
Another way to show/clean/prove this is to plug up all the ports in the manifold with silicone plugs. Pour in a pint of lacquer thinner, before the last plug, and the slosh the thinner around vigorously. Set the manifold on it's side, with the plugs facing you and wait a few minutes. Pull the plugs. There will be "media" sitting on the "floor"...sometimes staggering amounts. Note that to get an '85/'86 manifold clean, after media blasting, this may need to be done multiple times!

The '85/'86 manifolds are terribly prone to this problem...once the media gets trapped in this oil around the plenums. It is like cement...very difficult to remove.

The only way to prevent this, if using abrasive media is to completely clean any trace of the oil put of the plenums, before any blasting and dry the inside.

Any media which gets inside, after thus, is pretty easy to get out with the "silicone plug/lacquer thinner" approach.
.
I've seen this MULTIPLE times and have written volumes on this. It really shouldn't be a shock or news to anyone, but almost expected.