Help - Cracked Piston!

pjevo

Hello.

Looking for advice here please!

My Zafira timing chain snapped a year ago and although the pistons had light marks on them - I thought they may be okay. I replaced head and put eveythin back together.
Well I have a knocking noise from the engine at very light/no throttle. Full throttle there is definately reduced power.
I pulled out spark plugs and one has a tiny bit of wet oil on it. Looking down at the piston - it seems 'wet'!
I'm going to get a compression tester tomorrow - but fear I have a cracked piston or damaged rings. Although smoke doesn't appear?
Anyway - does anybody know if I can remove piston/rods in situ?

JohnnyN

If you PM Vocky, i'm sure he will be able to help you out. He knows the engine inside out.

;-)

vocky

all you need to do is remove the head and drop the sump

have a read of this thread.........https://z22se.co.uk/viewtopic.php?t=2971

got a spare set of pistons and rods if you need them

pjevo

Okay - was kinda hoping that you could just drop the sump and remove from the bottom. 🙁
I have done much engine development on VAG 20V and supercharged engines - which you do this on!
I'll do a compression test tomorrow to see what is up.

I may be interested in pistons and rods though - I'll be in touch.
I fear the bore maybe damaged - anybody got a spare engine lying around? 😃

pjevo

Spoken to Chris at regal and he confirmed my fears.
When chain snaps, the valves compress pistons, which pinch rings, which eventually lead to failure......... cryb..
Chris has a bottom end for a reasonable price.
I would prefer a drop in replacement lump though if anybody has one?

Mark_Dj

pjevo said:

I would prefer a drop in replacement lump though if anybody has one?

Try this place here....

http://cgi.ebay.co.uk/VAUXHALL-VECTRA-2 ... dZViewItem

luna_s

wouldnt new pistons and rods be better ? or does this render the block useless too ? - mine snapped and im planning on a rebuild with new rods and pistons, dont want to do it if the blocks broke

vocky

block should be ok, it's just the pistons are quite small and the impact of the valves damages the piston 🙁

pjevo

Yes - ideally and I have sourced some (read above).
Wish I did it properly when the head was off 🙁
From my engine experience, the block shouldn't be damaged, however....

Just wanted a drop in solution without tacking head/sump off etc, retiming etc.......

The guy above has a 30K 2.2 complete engine for £750, which I thought wasn't bad?

Anyway, going rods and pistons route and hoping block is not damaged 🙂

mjc2_2

My chain guide failed on my vec m8! 8 bent inlet valves replaced...dinks took out of pistons, all put back together! got it home smoke pissing out, it stalled twice at a couple of junctions. Got back to my mechanic and he says it's probably took piston....no shit sherlock! i was well pissed off! had new engine in the end, and demanded there be no labour charges either to replace the new unit,as i see it they should of given me the option of a full bottom end inspection, seeing as there is the obvious possibility of piston damage, which i would of paid for just for piece of mind.

pjevo

Recieved Vocky's pistons and rods this morning - thanks!
This inspired me to drop the sump and have a look.
Well I popped up the troublesome piston - which wasn't great.
But the real problem and this would explain noise was that bottom end bearings where completely shot - and I mean completely!
They had disintergated into each other - I'll post a pic soon.
Long and short of it is I think I have found the problem!

I'll examine the crank journals later, hope they are okay.
Also, bore's look okay although there is a tiny rub mark on one of the bores (with the damaged piston)..........