re: t-belt self destruct, big pics, long

[nynor]

i got the head off this morning. not as bad as thought, but bad enough. there are tons of pictures. anyone have ideas for getting the gasket material off of the block?

i don't think there is damage to the piston. the plastic piece that did the damage is in the pictures. notice the cut teeth, remarkably similar in shape to the plastic piece. also notice how well the piece fits the frayed edge. the top of the belt is where all the teeth are still good. bottom teeth are completely stripped. i can't find where the plastic came from, which is disconcerting.

also note the obviously bent exhaust valve. all the other exhaust valves have little smileys no their bottom edges, so i think EVERY exhaust valve was hit. none of the intake valves have a mark on them.

finally, check out the spark plugs. the cylinder, number three, obvously has more carbon deposit. number three is the only cylinder where the spark plug is facing away from the inside of the cylinder. perhaps there is something to putting those spacers on the spark plugs to make them face the inside of the cylinder...

[Zero10]

Wow, those look brutal.
Did the car burn any oil???

Hmm, with all of that carbon in there, I bet the compression ratio was much higher =)

[nynor]

actually, i thought they looked pretty good... no oil burning.

[ae1969]

The oil is not too bad........ I am assuming this is a high mileage engine?........... could be worn valve stem seals as well...

I wouldn't go to crazy cleaning the deck. I have used different scrapers, pads, also a scrubber I attached to the end of my drill..... You just dont want to gouge the surface. Also try not get any debris into the side of the pistons....

Looks like your diagnosis is correct. Looks like the belt was rubbing for some time............. Maybe at the last belt change the cover was not put on right? Where did the piece break off from ???

[nynor]

the belt could not have been rubbing. the part around the top of the cam wheel was perfect. the cut goes around about 2/3 of the belt. i cannot find the source of the broken piece. frustrating actually.

[ae1969]

On the back timing belt cover there are pieces of plastic that protrude out.....

I actually have my rear timing belt cover off on my NA. I will take a look at it when I get home....

[nynor]

i am at work now. i will take a look at that in the morning.

[Porsche-O-Phile]

Use #11 razor blades in a 45-degree scraping motion gently to remove the old head gasket material. You want the mating surfaces to be absolutely clean and smooth. Be careful because the steel of the razor blades has a greater hardness than the alusil of the block and you can easily scratch the deck mating surface.

Since you're doing all this, maybe yank & clean the pistons too. . . I'd recommend not wirebrushing them while still in the bores since all the crud ends up in the rings that way. I suppose you could use continuous suction but I've never tried it.

[SoCal Driver]

Good old paint scrapers work. Keep the edge filed square. Not sharp line a knife.

[nynor]

it would be pretty easy for me to use continuous suction. what about spraying liquid wrench on the pistons, or something like that?

[AFJuvat]

I use carb cleaner or degreaser

You can use a razor on the top of the pistons or a stiff bristled brush to decarbon them.

AFJuvat

[nynor]

degreaser it is. is a brass wire brush acceptable to use in the pistions?