Headgasket

[Leeboo]

Hi my head gasket is on the way out on my 1200 carb Nova... but just looking a bit more info.

Got the usual symtomns... mayo under oil cap, pressure in water system... but mayo inside the dipstick?? Never heard of that before.


Also.... perhaps unrelated, my engine will backfire out of the carb at low revs, like e.g. 2nd gear turning into a junction, will splutter a bit and let out a few spits from carb... then carry on as normal.

It will also sometimes cut out at junctions.

Yet on full whack/high revs it pulls like a train (as far as 1200's go).

Any info on dipstick mayo..... and spitting from carb...cutting out etc? Related?

[novaguy08]

spitting out the carb is a timing issue.

however the mayo all over the place is 1 of 2 things, either head gasket has gone or some condensation has got into the oil, is there any oil in the water??

check over the whole system & make sure that it is just a bit of mayo, not right throughout the oil! if its right throughout the oil then do the gasket, and whilst your at it, check the vacuum advance system & check that its working, change the cambelt & everything should do the trick :D

[Leeboo]

Had almost thought the spitting was a timing issue as I had been playing about with the distributor trying to get it running better, Got it running perfect apart from the spluttering at low revs. Will get a mate's timing light on it.

Well pressurizing is a sign of a failed headgasket isn't it? Its building pressure. The mayo was under the oil cap.. little bit on the two visible cam lobes under oil cap... and then a few lumps of it on the dipstick. The car has also been using a bit of water too, I thought it was just a slow leak but realising that most of it may be used. I thought the water smelt a little funky too. I have never had the mayo etc before now.

I haven't boiled her though... haven't blew the cap off or anything and fan hasn't kicked in?

Thanks

[Tommy_nova]

iv got the mayo prob with mine at the minute blowing the odd bit of blue ish smoke too when i boot it, im having some work done on the head this week also doin both belts hopefully this sorts it

[Leeboo]

Yeah not so good is it tommy. See the problem is... some vaux engines have mayo under the oil cap even if they are 100% fine... but the fact that mines pressurizing etc points towards a gasket.

I'm ordering a gasket tomorrow anyway... but when the something goes wrong I always like things explained :D

[Tommy_nova]

yea i got a new head gasket set plus bolts new oil filter plugs some fuel treatment and oil treatment and new oil the gasket was leaking abit but hopefully the nova will be all good for pvs after its had this little service

[AlexW]

Building pressure could be like you say, then it could be somthing else. Mayo on the oil cap could be due to be used for short trips.

But id say Head gasket, if its gone badly and the oil and water are mixing then you could get water in the sump, thus on the dipstick.

Just get it replaced, not expensive and get the head skimmed.

[Leeboo]

Thanks mate... yeah gonna replace it either way, was just curious. Not gonna get the head skimmed, ddin't overheat it so head shouldn't be warped

[AlexW]

Make sure its not warped though, and if you skimmed it you could gain .03 of a bhp lol

[Bobaling]

literally spent yesterday fitting a new head gasket as mine was split in two places and showing all the same symptoms as your nova

would probably flush the oil once or twice and definately throw on a new oil filter after fitting the new head gasket

[AlexW]

Yer, change the oil and filter once youve done the head gasket, and clean out the header tank at least.

[Leeboo]

Ok will do boys thanks.....quick question... my engine is a 12NV carb....will a 12ST (the square tooth carb engine) headgasket fit? They didn't list 12nv. So I've ordered a gasket for a 12ST, will it be ok?

[novaguy08]

thickness maybe different, other then that i cant see why not?

[Leeboo]

Ah I'll slap it on and hope for the hairy breast.

[AlexW]

Will be the same, When you get it, may even say your engine code on it.

[Leeboo]

Will be the same, When you get it, may even say your engine code on it.

happy days

[mowgli]

Ok will do boys thanks.....quick question... my engine is a 12NV carb....will a 12ST (the square tooth carb engine) headgasket fit? They didn't list 12nv. So I've ordered a gasket for a 12ST, will it be ok?

they will be different, the 12nv is a way smaller bore... why didn't you ask them to check an early corsa b????

there is one thing that nova owners never do.... clean out or swap the breather filter. it is under the inlet manifold, and if gummed up, will cause oil leaks, lumpy running etc

poor idle on a 12st could be a knackered advance/retard diaphragm in the dizzy

[Leeboo]

they will be different, the 12nv is a way smaller bore... why didn't you ask them to check an early corsa b????

there is one thing that nova owners never do.... clean out or swap the breather filter. it is under the inlet manifold, and if gummed up, will cause oil leaks, lumpy running etc

poor idle on a 12st could be a knackered advance/retard diaphragm in the dizzy

The corsa B never came with a carb engine. Are you not thinking of the c12nz SPi engine? Mine is a 12NV carb engine, just the round tooth carb engine, as opposed to the square tooth 12ST carb engine...surely there's no difference?

I cleaned out the oil breather while I had my starter motor off last week. There was a little bit of stuff in it but not much.

Thanks

[mowgli]

i apologise. I saw the N & thought it was the later type engine that is small bore & longer stroke & not as good.

[Leeboo]

No probs easy mistake... got the gasket anyway and it lists ST and NV.

Was just about to start changing it and realised I have no fcuking instant gasket for the cam carrier so need some of that :(

[AlexW]

Ive never used any between the head and cam carrier and have never had any probs.

[mowgli]

re the instant gasket, something like blue hylomar is fine, never ever use anything that will set solid like a silicone, always use a non setting type & then only just a smear.

[Leeboo]

Changed it yesterday and all is well.... had a load of water run out of the sump when I was changing the oil lol

mowgli... I just used some sorta blue instant gasket!!

Thanks for the help

[jimbob-mcgrew]

nice one, hows she running now ?
need to replace my gasket at some point too i think, she's getting tired.

[Leeboo]

Running twice as well lad, I took out lifters etc and immersed them in clean oil for a while etc...

Running lovely now and temp sits at a quarter out on the road and half way in traffic.

The only thing really pissing me off, is that I still have a (reduced) spit out of the carb the odd time at low revs. I've been told its timing, but it runs fine otherwise. Hopefully getting a mate's timing light on it later to rule it out.

edit - half the reason its running well now is probably because I swapped the distributor cap again... the one on it had little plastic filings in it and the round tip in the bottom that contacts middle of rotor arm, was mangled!!