GregBBRD

Jerry might not know that 928 engines have oil filters.

The only thing wrong with the cams is that they have some small pits forming on some of the lobes from the prior builder using stock 928 valve springs and used lifters on new cams with heavier intake valves.

Very hard on cam lobes.

blown 87

Tell me if I am off base here Greg, what I got out of your post was it ingested glass beads from not cleaning the intake, which took out the bores, that and a very rich mixture took out the oil pump due to oil dilution and damaged some other parts due to oil dilution, not due to glass beads in the oiling system.

Is that close?

FBIII

What are you two bat man and robin?

blown 87

Huh?
I have never meet the man, we are both pro mechanics that have been doing this kind of work a long time and have seen a bunch of the same stuff, but that is about as far as it goes.
I consider Greg a friend, but he is sure not going to cover for me if I am wrong, nor me for him.

I put something out there that would support the damage found and simply asked Greg if he was thinking along the same lines.

Glass beads in the intake are not going to get in the oiling system, at least I have never seen it, or heard of it.

GregBBRD

This is worth talking about.

I've now seen three 928 engines that consumed beads from not cleaning the intake system after it is powder coated.

Both of the other engines were way worse than this one....all of the cylinders got debris from the intake manifold.

This engine had the major amount of beads go down 3 cylinders.

Starting from the top of the engine and going down:

The beads hit the intake valves and work their way up into the guides. The intake valves get big ridges where the stems exit the guides.

The beads get into the combustion chamber and work their way down to the rings. The pistons rings literally get "sanded" away. On three of the pistons in this engine, the oil control rings are completely flat....there isn't two "ridges" sticking up anymore (one piece ring)....they are completely flat. The bores get damaged from the beads, as well as the pistons. The major "clue" that the damage is from a "foreign" substance and not poor cylinder preparation (although this engine did have poor cylinder preparation, too) is that there are scrapes above where the top ring travels in the bore. This is not possible without a foreign object getting stuck between the piston and the cylinder wall, on a properly made piston.

The beads next travel through the oil return holes in the piston and get washed into the wrist pins. The pins get "sanded" down very quickly and get significant "ridges" onto the pin and trash the pin bushings.

From here the beads get washed into the oil pan....there is too much oil escaping from the main and rod bearings for the beads to penetrate into the bearings, so the beads get washed into the oil pan.

The beads then get sucked up by the oil pump. This ruins the oil pump and damages the surface of the block that the oil pump touches.

Next step is the oil filter, which will eliminate the beads from the oiling system, trapping them inside the filter....in this case.

As long as the filter does not get "restricted" (plugged up) this is the end of the path. If the filter gets restricted (the first two engines I saw with this problem got restricted) the filter will bypass and the beads will get past the filter.

On this engine, there is no damge to the surfaces where the cams run. There is no bead damage on the bearings. The crank looks fine. There is no damage from the lifters running in the bores. I'd say that the filter did its job and stopped the beads, on this engine.

That being said, I would not re-use these lifters, from this engine, since they have a shelf inside which is almost impossible to clean.

This engine has 5,000 miles on it. You'd guess that the beads would be "long gone" from the intake system....I thought they would be. This is not the case. I removed the "side" covers from the intake manifold. There are still beads washing down from the "shelfs" inside the manifold, where the velocity stacks sit. I took a "swab" of this material and put it under my son's old microscope he had when he was young. It is, indeed, visually exactly the same material that is contained in my bead blast machine.

Jerry Feather

You are clueless Greg.

Jerry Feather

Jerry Feather

Good explaination, I mean the other Greg. JF

blown 87

Possibly wrong in this case, but far from being clueless Jerry.

If there were beads in the oil, there would be evidence of it downstream if it made it past the filter, just like Greg said.

Jerry Feather

I think that the clue that both of the Gregs are missing is that the "glass beads" that we are talking about are not really glass beads but the very tiny particulate that are left of the glass beads that have been blasted multiple of times in the bead blasting process so that they are broken down to small enough to pass the filter in any given engine. The filters in the engine will only trap particles down to a certain size and the others that are too small simply go through. Too, the oil filters do not filter all of the oil all of the time, so much of it is going to continue to be circulated throughout the entire engine.

The real question is how many of you are willing to run a batch of oil in you engine that has glass particles in it small enough to go through the filter.

Every surface in the engine that is intended to be treated with oil is going to be abraded by the glass beads or their particulate residue.

How is that for a clue.

Jerry Feather

SeanR

Oh good Lord.....

GregBBRD

Actually, I think Greg N. is one of the really smart mechanics that have the ability to work on these vehicles. There are others.....some post here. The people that really know these cars are few and far between.

I have great respect for Greg.

I'd be thrilled to work alongside Greg....be his "Robin"....anyday.

blown 87

I agree.
Done with Jerry in this thread.

blown 87

Wow, thanks Greg

robot808

You guys know about the ignore list, right?

GregBBRD

Jerry:

Sorry, I'm not going to play along with you, in this thread.

I've done that in a prior thread where you seem to think you have the ability to argue with me about a subject you have absolutely no personal knowledge about.

The same is true here. I've got the engine apart and have looked at it very closely. I prepared a ten page report for the owner, with detailed pictures of the damage. You've not seen this engine. You've not seen the damage. You simply have zero (0) credibility here.

None!

I'll say this (again) to you, Jerry Feather......you are a very interesting human being. And I'll add this, here: Although you are interesting, I find communicating with you very difficult as you seem to have some very strange unlogical thoughts.

And by the way...I haven't had anyone make up names to call me, since grammer school.

Seriously!