Thread: 3.9 V8 advice please.

Interesting moniker rpo83, don't have one do you?
Sounds like you may have a blown headgasket on that side, I don't think it is any more serious than a sticking valve, both require heads removal, do a compression test with all the plugs out, but first plug in a vacuum guage (tune up type).
Occasional drop in gauge means a sticky valve, steady regular drop indicates valve holding open, check first, then have a look at the head gaskets, Regards Frank.

Hi Tank,

Thanks for the reply, many years ago i used to have one, i got out of GT's in the 80's when i bought my 1st house. It is now motorbikes and 4x4's that keep me broke...

I have read reports of people fixing sticking valves with an oil change and a good thrash, it doesn't sound plausible but if i can figure out a quick easy fix without having to remove the heads i'm all ears...

I was thinking about removing the rocker covers and trying to get some inox down near the guides, what do you reckon, worth a try, or do i just bite the bullet and whip the heads off?

I am reticent to remove the heads as i will probably end up doing far more work that is needed, it is a personality trait i have

I usually think, well while i am in this far, i may as well check-- lifters, cam, valves etc

It is how i ended up building the RRC for 6 years

Cheers

Steve

A vacuum guage is a good investment, it will tell you if it is a sticking valve, unfortunately most sticking valves are the result of a bent valve stem and no amount of Inox will fix that, if you have significant blowby it is probably a gasket, between combustion chamber and pushrod hole letting gasses into the rocker cover. You may have to bite the bullet and whip the heads off, nice and light anyway.
I had an XY GT back in the 70's and a BA GT more recently, I bet you wish you still had the RPO83, worth big bucks now, Regards Frank.
P.S. I wish I still had the XY, megabucks.

sticking valve would mean that combustion gas slips into either the exhaust mainfold ... or .... intake manifold (depending on which valve is held open) ... but not into the block. Sign of it, would be a miss.

You sure about the "right hand side rocker cover is pressurized" and that the oil is leaking past the gasket, is not due to loose rocker cover bolts? ....

Either way , sounds as tho the head has to be removed .... But do the prelim checks first as per Tank


Cheers
Mike

I would go with a broken compression ring. Do a compression test. Blowby gases will pulse up through the pushrod drain holes into the rocker cover area.
Heads and sump can be removed in the vehicle to replace a ring or two.

Thanks guys,

i didn't think a stuck valve would cause the problem, the previous owners mechanic was the one who diagnosed it

I am hoping it is the head gasket rather than a broken ring. Is it possible to identify the type of head (10 or 14 Bolt) without removing the rocker covers?

I'll order a new gasket kit, any recommendations for quality VALUE kits???

I had a good look over the Disco yesterday, i am very impressed with the condition it is in. No rust visible anywhere, and the headlining doesn't have any problems.

The front sunroof doesn't seem to be sealed properly, i'll have to get a new battery so i can fire the electrics up and see if it just wasn't closed properly with the flat battery.

Here she is in all her glory..



Cheers

Steve