Wessy
Member
Registered: 30th Dec 03
User status: Offline
|
I have this Corsa C12NZ engine, it was using LOADS of oil and running
dog ruff. I whipped the 'ed off and found a burnt out inlet valve on no2
cylinder and a few scrape marks down the bore. The 'ed was also warped
so I threw it in the bin and got another 'ed. The new ( S/H ) 'ed was in very
good condition so I put it on, and the car fired up ok. It missed slightly at
first and then started to smooth out, it was still using loads of oil ( put this
down to the scraped bores ) This last couple of days it's been running dog
ruff again so I've whipped the 'ed of again, guess what ? same inlet valve
burnt out again ! Anybody got a clue why ?, piston is spotless in that cylinder so it looks like it aint been firing.
Sorry for the long post but keen to sort this one at as soon as possible,
ta Wessy.
[Edited on 25-05-2004 by Wessy]
[Edited on 25-05-2004 by Wessy]
|
Mattb
Member
Registered: 2nd Feb 03
Location: Under your sisters bed
User status: Offline
|
sounds like the valve isn't seating propely and getting mega hot, this may be due to a build up of carbon on the seat from the burning of oil..
thats only a maybe tho
|
PaulW
Member
Registered: 26th Jan 03
Location: Atherton, Greater Manchester
User status: Offline
|
quote:
Originally posted by Mattb
sounds like the valve isn't seating propely and getting mega hot, this may be due to a build up of carbon on the seat from the burning of oil..
thats only a maybe tho
if it was the head which was replaced & the original cam was used, then the cam could be causing this.
get a different cam next time with a replacement head, also may be a good idea to do the rings on the dodgy piston aswell just incase.
|
Mattb
Member
Registered: 2nd Feb 03
Location: Under your sisters bed
User status: Offline
|
if the cylinder bore is scored tho, this needs to be repaired also
|
mike_1.2LS96
Member
Registered: 23rd Oct 03
Location: Darlington | Mazda 323 1.8 Exec
User status: Offline
|
Yeah oil will be burning. Need a re-bore or new block.
I happen to be selling a whole C12NZ for about £60.
|
PaulW
Member
Registered: 26th Jan 03
Location: Atherton, Greater Manchester
User status: Offline
|
.5mm rebore on all cyl's should be fine with standard pistons & rings, but will need a higher-grade oil (20-50 or so)
|
Mattb
Member
Registered: 2nd Feb 03
Location: Under your sisters bed
User status: Offline
|
also clean pistons usually been bore wash which means the headgasket has failed, these questions may sound patronising but
did you replace the head gasket..
did you reuse the old head bolts
did you correctly torque up the head bolts
did you torque em up in the correct order
obviously if you have replaced the head you know what your doing but its always worth checking 
|
Wessy
Member
Registered: 30th Dec 03
User status: Offline
|
Well chaps thanks for the comments and all noted.
I whipped the 'ed to the local engine refurb shop.
It is infact an exhaust valve that has burnt and they
are just as mystified as me as to why it burnt as that
cylinder wasn't firing. " Bore related " was the conclusion,
also all the valve guides in it are shot. There must have been
LOADS of oil in that cylinder, valve seals are shot, coupled with
the worn guides and scores in the bore !
Who knows what was going on in there, the head is now
being refurbed, re-faced with new exhaust valve guides,
new valve seals, seats re-cut, 1 S/H exhaust valve fitted
and the whole lot washed with a head gasket set = £133
Not a bad price, interesting one of you guys has a C12NZ engine,
wish you were closer as it could have saved me some work.
The water pump is also shot by the way, 1 impellor blade out of
10 left, goodness knows what's happened to the other 9 !
Did you guys know that Vauxhall fit 2 types of exhaust valve ?
I is .75mm bigger that the other, other difference is price.
One is £8 the other £35, another mystery !
Keep you posted and thanks for the interest.
|
Wessy
Member
Registered: 30th Dec 03
User status: Offline
|
Forgot to mention, I actually bought a C12NZ engine, that's what I had the 'ed
and cam from. Mint nick 'till I nailed it on my old block with the scored bores. Bottom half WILL be changed this time, the old ones nearly out, and it's coming out without the gearbox aswell !
Regards
Wessy
|
mike_1.2LS96
Member
Registered: 23rd Oct 03
Location: Darlington | Mazda 323 1.8 Exec
User status: Offline
|
Well I hope it works ok for you, but what about the bores? If the oils coming through the pistons then its just going to happen again?
|
mike_1.2LS96
Member
Registered: 23rd Oct 03
Location: Darlington | Mazda 323 1.8 Exec
User status: Offline
|
missed the 2nd post
|
Wessy
Member
Registered: 30th Dec 03
User status: Offline
|
Engine block now swopped, just need to
nail everything back on. Gearbox stayed in
just had to remove the offside drive shaft
as the flywheel just caught the inboard
CV joint.
|
