FredR

Must be gut wrenching to experience something like this but very impressed by your philosophic view point and wishing you are great outcome for whatever $$'s you are are into here.

Failure of the small end bearing is very rare indeed- easy to understand why the piston was ground out but the wrist pin? Presumably the blasting media just gets into everything once it enters the engine.

Rgds

Fred

DKWalser

Right. It appears the blasting media becomes suspended in the motor oil. Instead of lubricating, the oil becomes a liquid abrasive. It seems a lot of damage can be done before the filter has a chance to do its job.

GregBBRD

The "first pass" of cleaning Van's manifolds had lots of loose silicon beads coming out. Somewhere packed into a corner was this, which came tumbling out....



Like I said, the construction of the S3 manifolds make them a very special challenge to clean.

GregBBRD

To give you an idea of how much silicon media it takes to do damage, several ring makers now caution their users to not bead blast the tops of pistons. They claim no matter how much you clean the tops of the pistons, a tiny percentage becomes imbedded into the aluminum, which comes loose when the engine is run....destroying the rings.

This stuff is really nasty.

GregBBRD

Fred:

I've done quite a few of these engines that have failed due to beads in the intake system.

It's a really interesting "progression" of damage.

The beads go from the intake system into the intake ports. The intake valves get ground down to 6.5mm stems and the guides become 7.5mm guides.....huge damage.

From there it gets into the combustion chamber. Once here, it gets on the cylinder walls and sands down the pistons and rings. The oil control rings feed the wrist pins (unless you own a GTS I haven't rebuilt, yet). The wrist pins end up looking like a piece of bamboo and the piston and wrist pin bushings get wiped out.

From here, the stuff makes it to the oil pan, and gets sucked up by the oil pump. The stuff destroys the aluminum surface that the oil pump spins on (the block)....along with the gears and the oil pump housing.

Next stop is the oil filter, where the stuff is stopped (until the filter bypasses from being plugged.....this happened in Van's case). Amazingly enough, the rod bearings looked pretty nice!

Jherriott

I love the "death-stare" FDR is giving that offending muck! LOL!

zekgb

Other than the pocket change coming out and the fact that my coater used aluminum oxide instead of beads this was exactly my experience with the plenums in each corner behind the velocity stacks. Until I squeezed my hand inside and could feel exactly where the stuff was hiding there was no way I was getting it all out of there.

GregBBRD

Here's what came out after the "4th pass" of cleaning. This "pass" was pressure washing with special 110 degree nozzle (3rd time) followed by blowing with a custom bent air nozzle, and then a rinse in my sink.



Still have nore cleaning to do!

zekgb

Are you only finding stuff in the plenums or are there beads embedded in the runners as well?

bureau13

It's settled: I am NEVER bead blasting my S3 intake. NEVER. F*** that.

FredR

Greg,

Some illuminating info there. That is a scary amount of crud considering that is blasting media that did not make it into the motor- makes one wonder just how much did!

I had my inlet manifold grit blasted some 10 years ago but only on the outside. I knew that that the process may well "peen" the alloy surface - in fact it would be more accurate to describe it as "pock marked"- an interesting cosmetic effect when painted giving a matt finish when painted that is not at all bad to the eye and with a protective coat on it actually shines quite nicely [pure good luck that one].

I reasoned that if the metal is that soft then grit may well embed in the metal surface and for that reason did the outside only rationalising that if some of the original coating on the inside did break away it would do much less damage than trapped blasting media would.

Kind of sounds as though I might just have called that one correctly.

Feel sorry for Van- sounds as though the short motor may be a total loss -I suppose the crank case may be recoverable with a new bore/oil pump and the rods will still be viable- hmm! Interesting that the big ends survived - one might have thought they would be the most vulnerable part given clearances etc unless the media particulate diameter is such that it just cannot get into bearing clearance gap if that makes any sense [?].

Rgds

Fred

GregBBRD

The runners were covered with a fine layer of beads.

My guess is that the powder coater did not clean the plenums to begin with....and the beads stuck into the oil (always lots of oil in the S3 plenums). The beads stuck into the casting areas where the velocity stacks are cast into the plenum....in a clay like fashion.

The material in the picture with the dime is silicon beads stuck together with oil....it is literally silicon clay.

I've cleaned and cleaned these plenums.....ended up making some new air nozzles to get all the silicon out.

In my opinion, Van didn't have a chance of getting this stuff out.

zekgb

Yeah the guy who did mine took a look at the plenums and sent everything a couple of doors down to a machine shop to get them hot tanked prior to blasting with aluminum oxide. I found zero media in the runners and the stuff I found in the plenums was kind of clumped in the the corners behind the velocity stacks so maybe it wasn't 100% dry when he blasted, but clearly a lot better prepped than Vanster's.

DonaldBuswell

Interesting read! I'm professionally interested in this market for media blasting these engine intake manifolds. I just recently completed my S4 Intake and Cam Covers...and every forged aluminum suspension piece and such under the body.

Imo000

Is your insurance large enough to cover an engine replacement when you make a mistake on a customer's part?