Cracked Piston?

[Pudock]

I know that its hard to judge from a photo, but does this look like a crack that I should worry about or is it just a score?

The head is of to replace piston rings on the number 1 piston. This is number 2 piston.

Thanks

[Les Henson]

Looks like a crack to me, but then it's hard to judge from the pic (what would make a score like that inside the engine?). TD's are well-known for pistons cracking, and I've seen a fair few. Usually - a cracked piston will allow compression to pass through the crown and into the sump, where oil is then pushed out (usually) the breather pipe and into the air filter.

Have you cleaned the piston crown prior to taking the picture? A crackerd piston crown is usually black - due to the reduced compression.

Les.

[western]

looks like a score mark, if you have a magnifying glass or similar have a good look at it,

TD pistons do crack with age/heat stress on the engine, so changing all 4 might be a better move.

[Pudock]

I did not clean it much before the photo, just a wipe with a rag. Pistons 3 and 4 had more burning on them than that but are fine. Piston 1 is fine but it was covered in oil.

I'm hoping not to spend to much fixing it. The only reason I took it apart myself was I could not justfy the expence of getting the garage to open an old TD up to tell me that its all shot. So I'm trying to balance between repairing or replacing the engine.

Thanks for the answers guys

[Mo Murphy]

Time for an old Disco 200

Mo

[Les Henson]

I have never yet replaced any piston on a TD engine - other than those that are cracked (usually 2). Piston kits (piston, rings, piston pin, circlips), are only about £20-£30 each, so no great expense really. A head gasket and maybe rocker gasket, inlet/exhaust manifold gaskets, some RTV sealant for the sump (or a series sump gasket if you prefer), will set you back about another £30, so a couple of hours overtime will cover the total cost of repairs

Les.

[trickydicky]

hi mine were alot more cracked than that and they didnt cause me any probs . when i did change them i found that it drank the oil for the first 500 miles or so but now its fine .the hardest part was lying on my back with oil dribling on my face but at least i sorted the leek on my sump .

[Pudock]

On a slightly different note, the rings on my pistons are on in a different order from what the manual says. My rings are oil control at the bottom then chamfered ring and then square section at the top while the manual says the chamfered ring should be at the top. Does the order really matter as the pistons have never been out in the 10 years I've had the car?

[Les Henson]

The chamfered ring should be at the top so that the step that eventually forms at the top of the bore doesn't snap the ring. Should be chamfered, straight edge, oil control.

Les.

[Pudock]

The chamfered ring should be at the top so that the step that eventually forms at the top of the bore doesn't snap the ring. Should be chamfered, straight edge, oil control.

Les.

Thanks Les, I'll put them in the way you and the book say rather than the way the old ones came out.