KV6 misfire & cutting out.

[Robbybb]

My previous post was a week or so ago regarding a random misfire and associated annoyances.
After replacing a suspect coil pack, fitting new plugs and having a long run, my local garage has identified a leaking exhaust valve and estimated at least £1k to fix it.....

It's not a job I would attempt myself so is there anyone within a reasonable distance of Dorset who might want to have a go? I have seen a guy on here who says he can do a V6 head gasket replacement for under £500 but can't find him now but i'll keep looking.

Has anyone any ideas or can point me in the right direction?

Thanks

Rob.

[SD1too]

... my local garage has identified a leaking exhaust valve and estimated at least £1k to fix it.....
Rob; I would thank them for their diagnosis and file it, then continue the search for the cause of the misfire.

Do you have a lot of oil ingress into your throttle body and inlet manifold chamber?

Simon

[murphyv310]

Do a compression check in the first instance to either confirm or dispel that diagnosis.

[Robbybb]

Thanks guys.

The garage have done a compression test and Cyl 6 came up with about 40psi against around 160 on the others. Other symptoms being sooty tailpipes, 24mpg, occasional pops and crackles on the over-run, lumpy running at low revs but a surprising amount of smooth power over about 1500rpm.

Do you reckon this bears out their diagnosis? I used to decoke my 1275GT on a Sunday morning in the 70's and be driving it in the afternoon but today's cars are beyond me...

[SD1too]

As Trevor says, do your own compression check (as £1,000 is at stake). Cylinder no. 6 will be fun. ;)

Simon

[Phil-T4]

If it's an exhaust valve leaking then a leak down test will pick it up easily.

[murphyv310]

If number 6 is down as you say and there is popping in the exhaust I'd be inclined to agree with the diagnosis. One other thing is the possibility of a stuck hydraulic lifter keeping the valve open slightly. Snag is that seat and valve burning will have occurred so the head needs to come off I'm afraid.

Your symptoms are classic of a burned exhaust valve. Been there a good few times over the years with mine and friends cars.

[Salad-Dodger]

Do that compression test. If number six is low, give it some oil and re test it. If it goes up, its rings. If it stays about the same, its probably a valve. Steve