Cracked Piston ?

[Martinaston]

Would anyone know how bad this could be ?

The belt broke by the look of it and it's definatly a crack and not a dent, but is it worth changing the piston or useing it ?

[Dan318-is]

only a fool would re use that piston

it would also be advisable to check your bores if you could while youve got the head off!

buut definaly dont reuse the piston mate, think of the strain it has to undergo everytime you run your engine

a new one cant be that much either, just dont risk it man!

[E30Mark]

bin it!

get a new one or a good second hand one....

[BrAdZ]

100% sure its cracked>? just looks like a scratch to me?

[TOURINGDADDY]

if ur not sure to the bin it goes!

[Martinaston]

No i'm not 100% unless i pull it out but if i do that i may as well change it.
it looks like it was done before the belt went because the carbon is in the crack
Not too sure about the gudgion pin either, Does anyone know of a sure fire way to tell ?

[Demlotcrew]

Is it really a crack?

Andrew

[Martinaston]

pretty sure,
you can see the change in colour of the indent from where it used to level out and where the valve has rounded it off.



Just looking for excuses not to pull the whole thing apart realy

[Apal]

Have to say that from that angle it looks suspiciously like a crack that has started in the corner of the valve pocket - corners often act as stress raisers. Can't be sure without seeing it in the flesh though.

If those are 2.7 Eta pistons I think I still have a set in the garage. Let me know.

[kam-325i]

I would change it...

[Dan318-is]

No i'm not 100% unless i pull it out but if i do that i may as well change it.
it looks like it was done before the belt went because the carbon is in the crack
Not too sure about the gudgion pin either, Does anyone know of a sure fire way to tell ?

To check gudgeon pin the piston needs to come out. You need to check for play between the piston itself and the rod. 0.041mm is the max tolerance iirc?? i think on early m20 engines not sure about late ones, mtie be the same tho

[Martinaston]

Cheers 318-is
are you sure that can't be checked with the piston still in place?

(please say yes, please say yes, please say yes)

[kirils]

maybe you can re use the same piston but the car will not work properly, it was a really bad hit, and this kind a case it's good to take out the engine cause the ( i have a bit problem to say this on english) the spinning thing that holds the pistons might be damaged, so if i were you i would took the engine out rebore it for 0.5, buy new pistons bigger for 0.5, change the bearings, and you will have a new more powerfull angine and i guarantie you that you will make more than 150k miles without problem

[Martinaston]

KO
(Crank)
do Good idea i'll that.