Bart-Jan

After a year working on and off on the car, I finally had everything together and at first startup, I noticed it sounded like a bag of bolts and nuts had fallen into the engine. Even worse than the coldest old-fashion diesel engines. I switched it off and removed the spark plugs. The top of cylinder one was damaged so I took of the intake tube and turned the crank until the valve was completely opened. I made a white LED on a wire that I dropped into the cylinder to get some light in there. The top of the piston is only minor damaged and the cylinder looked perfectly okay. In fact, there was a '+' marked on all pistons. So I guess it allready has it's first oversized pistons. The honing grooves were also clearly visible and the top of the pistons looked really clean. So this was the good news. The bad news was, I saw nothing laying on top of the piston... So with a thick piece of aluminium wire, I gently scratched inside to feel the inside of the cylinder head. I felt a hard particle that didn't belong there. Whith som 'persuation' it let go and dropped on top of the piston. With a small hose attached to the vacuum cleaner, I took it out. It looks like a piece of a bent piston ring. However, I think it is much to small for that purpose, although it looks like toughened steel. Any idea what it could be?Attachment 406735

Anyway, after I took it out, the car started up fine and sounded okay. At first a loud ticking sound from the valves, but after warming up, it was completely quiet! The only thing that I noticed was that it vibrates a little when it idles. Is this normal? I can't remember how it was before I took it apart.

Of course it is best to take the cylinder heads off and renew at least piston no. 1. But I would like to finally drive the beast...

aj986s

I have no idea where that piece might have come from.

Before pulling the motor apart, a relatively simple exercise might be to do a compression test on each cylinder. This could help to make sure that tidbit didn't A) come from a ring and is now causing a poor seal and compression loss, or B) didn't damage the valve seat if it came through the intake somehow. In either case a loss of compression would possibly cause the lumpy idle you describe, because the cylinders are no longer making consistent power.

SnakeFeeder

Seems obvious to me...
Aliens.
(< ^ > |~)

Ducman82

if that was part of a piston ring, you would have bigger issues. im not sure what that is, is it square of if you look at if from the end?

Mrmerlin

If would please add your car info to you post .
If you can get, your hands on a borescope you can put the piston to BDC and then inspect the top of it for a crack or possibly a chip out of the top where a ring would be.
I dont think this is a ring however, as it has no curve to it and the edges are not sharp enough. Anyway can you please detail the work that you had dont just prior to running the engine? In other words what was the last thing you fixed??
Did the heads go out for a valve j0b?
just new headgaskets,
an intake refresh??

blown 87

Is it magnetic?

Herman K

Plus + on the compression test and possible cause of a lumpy idle > The piece is 17mm x 2 (bend but still attached) that would be a 34 mm piece of a piston ring that would only come out of the groove if the piston is damaged. Did you check if your maf screen retainer clips are intact?

lrpman

Looks like a piece of a cotter pin but the Bore-scope is the ticket and the compression test.
A leak down test for the cylinder in question might also be in order.
Hope you find no major damage.

Bart-Jan

The part is square seen from the side and looks broken on one side. As if it were a ring that has been smashed. The wire is about 1 mm square and is iron, since it's attracted by a magnet.

My car is a Euro 16v from '85 and I wanted to change the headgaskets so took the inlet apart and reconditioned the complete inlet system, including the fuel system. When I found some magic stuff that's said to repair broken headgaskets, I thought I'll give it a try. It saves a lot of work and money and a Porsche specialist nearby has used it on several 928's with great succes. Until now, it is still succesfull and no more white smoke and loss of coolant. But I'll wait until the nice weather arives before using it on the road again.

I thought about a borescope, but don't know anybody having one. I was thinking of maybe buying a spy camera that is small enough to put through the plug hole and connect it to my laptop. Anybody got ideas for one small enough?

It can't be a part of the MAF screen retainer clips, since I removed them; I'm running Megasquirt and only use the MAF as a tube connecting the air filter to the inlet system.
BTW, what is a cotter pin?

I'll do the compression test in spring (first I'm going on a long holiday for two months...)

blown 87

A top or second ring is to brittle to bend like that.

Cosmo Kramer

I agree that it isn't a piece of piston ring, no way it would bend almost 180 deg around like that. It almost looks like a piece of a metal ring that is embedded in a head gasket.

Bart-Jan

If this were true, than my head gasket is REALLY blown!!! Although I think it was another cylinder that blew.

Are there more people recognising this as part of the headgasket? If so, then there's probably more to come and I would have to take everything apart before more disaster strikes me...

lrpman

Look at a new Head gasket and see if it LOOKS like the metal sealing ring at the cylinder. I THINK that it is NOT unless it is a channel shape to slip over the lip of the gasket material proper.
How does the spark plug look from that cylinder compared to the others after running the car? OIL?, SOOT, RAW FUEL (wet) this will give you a quick read on the health of the cylinder.

docmirror

Also might want to perform a leakage test on the cooling system. Sometimes the pressure applied to the head by a small bit like this will warp the head enough to cause a coolant leak. There are coolant leak testers at radiator shops. Just pump it up to about 12Lbs(.8 bar) and wait for a while. If coolant is leaking out the side, it will show up above the exhaust manifold. If it is leaking into the cylinder, it will show up as white smoke and rough running when the engine starts.

blown 87

It looks to thick to be part of the head gasket.

My bet is something got dropped into the cylinder during some work you were doing.