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[silkyskilz1970]

.........looks like the head gasket has blown on my MV6  looks like the twonk who sold it to me saw me coming 

i'm gutted as i wanted to keep this one (my 3rd MV6)   but i've given up with it now, have done several things to cure it's misfiring and lumpy running, in the last couple of weeks she's had:

new dis pack, plugs, leads
the starter motor was swapped out recently for one from a scrappy (what a job that was)
other little jobs done as well as i went along (door solenoid & various other things)

didn't get around to doing the abs ecu, rocker gaskets & putting tyres on the front alloys as i had planned for this month

she's a nice one too - silver facelift with leather, has a stainless exhaust from cat back, bodywork in very good nick (hardly any 'tesco dents' - just the usual bit of corrosion around the rear arches

i'm gonna stick her on the bay tonight and see what i can get for her as spares/repairs

if anyone is interested (or knows anyone that might be) in a breaker car or for repairing then PM me

wish me luck folks

[joshwyatt]

What makes you think the HG has failed? Oil in the water? Is there any 'mayo' on the dipstick? With the help of OOF you may well be able to save it.
After the new dis, leads and plugs was it still missfiring or running lumpy?

[The Red Baron]

are you sure its the hg & not the oil cooler.

must type faster josh 

[silkyskilz1970]

no evidence of water in the oil

still missing and very lumpy, my mechanic reckoned the HG or it's thrown a piston

what symptoms does the oil cooler give?

[silkyskilz1970]

also, when the starter motor self-destructed i think it may have damaged the flywheel  :-/

[Kevin Wood]

still missing and very lumpy, my mechanic reckoned the HG or it's thrown a piston

Hmm. I think you'd know about it if it had "thrown a piston".  Faced with advice like that, I'd find another mechanic. 

Back to basics. Head gasket failure is the least likely scenario on these engines so:

Any evidence of oil in the water?

What evidence is there (other then a misfire) that suggests head gasket failure?

Is the compression OK?

Any fault codes from the engine ECU?

Any oil / water getting into the plug wells?

Is the DIS pack in good condition? No cracks in the casing?

Kevin

[PhilRich]

Check the coolant bottle. If it is badly contaminated with oil then that is a good indicator the oil cooler has failed.

[silkyskilz1970]

hi kevin

compression is down on cylinders 1 & 3, however no compression gauges applied, cannot see oil in the water

there is a little oil in the plug wells but not a huge amount

dis pack is new as are the plugs & leads - replaced in the last week

the exhaust pipes are very very black and the exhaust gases are very wet

marc

[tunnie]

hi kevin

compression is down on cylinders 1 & 3, however no compression gauges applied, cannot see oil in the water

there is a little oil in the plug wells but not a huge amount

dis pack is new as are the plugs & leads - replaced in the last week

the exhaust pipes are very very black and the exhaust gases are very wet

marc

How can you tell if the compression is down on pots 1 & 3if no gauge was used?  :-/

V6's produce a lot of condensation when cold, its fair to say when stone cold in this weather, the V6 looks more like The Mallard going full chuff...

Nothing here is screaming HG, i'd echo above, if the machine says 'piston or HG' he clearly does not know a steering wheel from a boot lid.

Have you run a 'paper clip' test to run fault codes? A simple air leak can cause lumpy running and missing.

When the plugs and leads where replaced, are you sure they are wired up in the correct sequence on the DIS pack?

[mantahatch]

Give you £50 cash for it collected 

[Lazydocker]

I'll echo the above comments... Doesn't sound like HG to me. The very black exhaust hints more at overfuelling to me.

Reckon it may well be an air leak causing the rough running, probably one (or 2) of the 6 large o rings under the plenum... Pots 1 and 3 perhaps

[mrgreen]

also, when the starter motor self-destructed i think it may have damaged the flywheel  :-/

why do you think that? if it's not catching sometimes or running slow it can just need shimming out takes a bit to ruin a flywheel but not unknown to happen, I would stick with it you seem to know which end of a spanner is which, with the help from this forum you could sort this out and have a good car, better the devil you know and all that

[TheBoy]

The major thing wrong, it would appear, is the mechanic  .

Don't worry about condensation from exhaust - water is a by product of combustion, and with the cold temps, it condenses as it leaves the pipes (or before!)


How do we know the compression is down on 1 and 3?  Its worth knowing that HG failures on V6 that causes the firerings to give up are incredibly rare.


My gut reaction is air leaks, given the symptoms.

[Psychoca]

also, when the starter motor self-destructed i think it may have damaged the flywheel  :-/

why do you think that? if it's not catching sometimes or running slow it can just need shimming out takes a bit to ruin a flywheel but not unknown to happen, I would stick with it you seem to know which end of a spanner is which, with the help from this forum you could sort this out and have a good car, better the devil you know and all that

Fully agree, they are a very heavy lump of cast iron, which is not likely to be affected by a starter motor going pop...  I would be looking at other areas...

Did you change the plugs/leads/dispack or your mechanic???  Might be worth a look at them to make sure that they have been changed and that they have the correct gap set...

[Andy B]

....
Did you change the plugs/leads/dispack or your mechanic???  Might be worth a look at them to make sure that they have been changed and that they have the correct gap set...

Assuming they are GM plugs fitted you fit them to the car straight from the box, you can't actually gap them.