928mac

Gee I guess you guys don't know every thing then.

Have you heard of cylinder taper.

yes there is a difference. Take a spare o-ring and through it is some diesel for 15 min. it will swell.

928mac

really;
which brand and model, I will bet on that you are wrong.

namasgt

So that liquid was there when you pulled the head off ?
I'm asking because maybe Greg Brown is right, maybe whatever that stuff is caused the hard carbon that forms around the rings to gum up and cause the rings to stick. Also its hard to believe that, that engine was not opened before, those pistons look too clean for a used engine....

gbgastowers

You could tell by the undisturbed condition of the fastners that it had never been opened up. The PO was a guy kinda like me in Florida that gave up on it and got a 4.5L that would start but was bad somehow so now he has put in a LS1. Maybe he was putting stuff in the cylinders that cleaned off the pistons in his efforts to start. Gunar

gbgastowers

pictures of the engine when I got it and opened it up.

gbgastowers

2222

neilh

Looks like PO dumped a load of Seafoam into it to try and solve the problem.

gbgastowers

What explains the water jackets being so clean?

gbgastowers

3333

Imo000

I agree, those pistons and combustion chambers are waaaaay too clean. Looking at the valves, this engine was steam cleaned a while ago and then it sat.

blown 87

Sure, I have heard of cylinder taper, and it is ALWAYS bigger at the top in a engine that has been run, at least in every one I have been in, and it is a pretty big number of them.
Why do you think there is a ridge at the top of the cylinder of a worn engine?
New engines should have ZERO taper.

As far as swell, depends on they type of material in the o-ring, take a rear main from a 928 and try it, see if it swells, or the o-ring from the check valve in the head, I will do that test tomorrow.

And what do you think it is going to do to a main bearing?

Sorry, but you are wrong about this, well maybe not the seals, because I have never tried it, but I an going to be shocked if it will make a 928 engine o-ring or seal, swell.

Hell, the rear main for some of the VW engines are the same for the gas and diesel versions, same part number, the return hoses are the same stuff.

dr bob

The engine may have suffered from a failed head gasket, and the piston steam cleaning would be the result of water/coolant ingestion.

For the OP, I'd consider a bit of Marvel Mystery Oil, or a blend of ATF and acetone, sprayed into the cylinder. let it sit a while with plugs in loose, like for a week. Spray more in during that week to make sure the rings stay wet with the stuff. Then pull all the plugs, disable the ignition, and hand crank the engine through a few revolutions. Then crank with the starter, with towels over the plug holes. When ll the junk has ejected via the plug holes, run your compression test again. If the rings were just gummed this may help free them.

But... Water-washed cylinders don't lube the rings well. A partially hydro-locked engine will often show with compressed ring lands and grooves, pinching the ring. The overheating associated with the coolant loss from that blown headgasket will ruin a set of rings, taking the spring out of them. They need some spring to stay against the cylinder walls.

namasgt

All the cylinders are clean, the steam could have flowed in to the intake plenum and got sucked in to the other chambers but that would take time and a huge head gasket leak to do a good steam cleaning like that, plus it would be noticeable when looking at the head gasket and head. And if you look the coolant is green around the jugs but the stuff in the chamber is clear with some foam on top of it. Someone physically put some thing in there. I still think you have a flow problem. But if I had opened the engine and saw that stuff in there, I would have taken it apart to see how the rings look and replace them.

Roy928tt

Guys,

As a Qualified Diesel Mechanic I'm going to come out in support of Brad, Diesel is no good for many 'O'rings and seals. Engine seals in petrol or diesel engines are not directly exposed to fuel, only oil, and the oils are not so dissimilar.Caterpillar even make '0'rings exposed to different situations, different colours, nice and simple for the American folks, eh Brad.


Diesel dilution of engine oils is a serious and intolerable situation, to be remedied immediately, as diesel breaks down the lubricative properties of engine oil.

As for cylinders, I always assumed that cylinders were machined parallel, no taper. But you know what assume will do? make an *** out of U and ME ! I'll investigate that one more.

So Gunar is going to soak his pistons and bores in Auto Trans Fluid and see what happens ?

Cheers Roy

Landseer

I think getting compression up across 8 cylinders so that you have a long term reliable engine using such a soaking method is asking a lot.

Once you get beyond the mental anquish of it, pulling the biatch out, especially clean as it is, might be the better approach.

Now, I haven't done this on the 928 (yet).

Can't you then just pull the pan off, keeping track of everything, undo the rod bearings and liberate each one.
Crank / mains don't need to be disturbed, nor lower cradle, right?

I guess you would need a groove cutter to dress the top edge of the cylinders when pulling the pistons?
You would need rings for the 4.7.
Probably get away with the same headgaskets, being they are new.
Not sure about the studs / nuts
I have a spare set of pistons / rings, but unfortunately they are 5L.