Found myself a new mechanic (Jag rebuilder & collector) called with me
Saturday diagnosed valve stuck open, caused by a piece of carbon, as the
reason for zero compression. He changed all 12 plugs and cured the problem
Help me out here guys. How would changing spark plugs have an impact on a
valve
stuck open by a piece of carbon? If a valve was stuck open by a piece of
carbon, how would one deal with it, without disassembling the engine?
Drive the
car near red line for a minute or two?
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
2
Maybe with old hot-rod trick to spray water in engine thru carbs or
injection
when it is rewed about 2000 RPM.
Sounds cruel but works.
Well, don’t be trying to figure out how to spray water through the
injectors. Into the air intake is the way the old hot-rod trick was
done. I dunno if I could bring myself to do it on the Jag V12, since
it is VERY hard on the engine (basically fracturing all the carbon
and deposits off the combustion chamber surfaces) but I suppose if
the alternative is a complete engine rebuild anyway it might be worth
a shot.
I’ve always wondered just how much water is involved. Do you spray
an entire garden hose worth? Or something more like a gentle mist?
On the Jag, I suppose you could do it one bank at a time.
There are also products for similar effects. There’s some stuff
you’re supposed to spray into the intakes while the engine idles, and
supposedly the carbon will soak it up. Then you blast the throttle
open a coupla times, and the stuff breaks all the carbon loose and
blows it out the exhaust. I tried it once, it didn’t seem to have
any effect on the car involved (good or bad), but perhaps carbon
buildup wasn’t really the problem with that car to begin with.
– Kirbert | Palm’s Postulate:
| If anything is to be accomplished,
| some rules must be broken.
| – Kirby Palm, 1979From: “Peltomaki Aleksi (NTC/Zurich)” aleksi.peltomaki@ntc.nokia.com
Maybe with old hot-rod trick to spray water in engine thru carbs or
injection
when it is rewed about 2000 RPM.
Sounds cruel but works.
I believe one of the Jaguar authorized fixes for carbon build-up and oil
build up on the inside of the inlet manifolds, (especially for cars that are
driven at low speeds all the time) is to hit the highway and hold the car in
second at around 90 mph for a few minutes!
Certianly something the average XJ-S owner can do without going to a
dealer for.
Found myself a new mechanic (Jag rebuilder & collector) called with me
Saturday diagnosed valve stuck open, caused by a piece of carbon, as the
reason for zero compression. He changed all 12 plugs and cured the problem
Help me out here guys. How would changing spark plugs have an impact on a
valve
stuck open by a piece of carbon? If a valve was stuck open by a piece of
carbon, how would one deal with it, without disassembling the engine?
Drive the
car near red line for a minute or two?
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
5
I believe one of the Jaguar authorized fixes for carbon build-up and oil
build up on the inside of the inlet manifolds, (especially for cars that are
driven at low speeds all the time) is to hit the highway and hold the car in
second at around 90 mph for a few minutes!
It’s been quite a while since my car had a GM400 in it, but I recall
a day I tried to do something like this. I had the shifter in 2, and
was haulin’ ass, but it was a winding road so every now and then I
needed to let off a bit. Each time I’d get my foot out of it, it
would upshift! And then the instant I got back on it, it would shift
back into 2! Drove me nuts. Does everyone’s GM400 do that? Or was
mine ailing for some reason?
A good screaming run is often just the ticket (!) for what ails a
high performance engine. If the run itself doesn’t fix it, it’ll
make only too obvious what the mechanic needs to fix AFTER the run –
burnt pistons, swallowed valve seats, whatever. I’d kinda advise
that if one’s car doesn’t seem to be running well, it might be a good
idea to check a few things BEFORE making such a run.
– Kirbert | Palm’s Postulate:
| If anything is to be accomplished,
| some rules must be broken.
| – Kirby Palm, 1979From: scott.horner@telecom.co.nz (Scott Horner)
Maybe with old hot-rod trick to spray water in engine thru carbs or
injection
when it is rewed about 2000 RPM.
Sounds cruel but works.
I believe one of the Jaguar authorized fixes for carbon build-up and oil
build up on the inside of the inlet manifolds, (especially for cars that are
driven at low speeds all the time) is to hit the highway and hold the car in
second at around 90 mph for a few minutes!
Certianly something the average XJ-S owner can do without going to a
dealer for.
Cheers
Scott
1976 6.5 liter V12 XJ-S
–
This mail is a natural product. The slight variations in spelling and
grammar enhance its individual character and beauty and in no way are to
be considered flaws or defects.
Maybe with old hot-rod trick to spray water in engine thru carbs or
injection
when it is rewed about 2000 RPM.
Sounds cruel but works.
I believe one of the Jaguar authorized fixes for carbon build-up and oil
build up on the inside of the inlet manifolds, (especially for cars that are
driven at low speeds all the time) is to hit the highway and hold the car in
second at around 90 mph for a few minutes!
Certianly something the average XJ-S owner can do without going to a
dealer for.
Cheers
Scott
1976 6.5 liter V12 XJ-S
–
This mail is a natural product. The slight variations in spelling and
grammar enhance its individual character and beauty and in no way are to
be considered flaws or defects.