2002 jeep

[hypostang]

Does anyone know how in the world to diagnose which cylinder is knocking on a coil on plug straight six jeep :eek:
I usedt'could remove one wire at a time till the noise changed :D


My son in law has one of these beasts that is making all kids of racket and I dont want to start tearing into it until I know a more specific place to hunt
..or should we just pour some motor medic in and head to the trade in lot ?

[hypostang]

No ideas how to short one cylinder at a time ?
is it even possible with this engine ?

[04Ultimate]

How about one of those stethascope type thingies with the rod on the end instead of the cup? If you can get the end of the rod to the cylinder sides maybe you can hear which one's the culprit.

[hypostang]

I tried that and all I can determine is that it is noisy as hell :p
I don't want to even be involved with thing to be honest it runs just fine but is just noisy ... turns out he paid way to much for it and is stuck with it for the next 3 years

[Drake_tr7]

I have to agree on the stethescope, I keep mine handy. On one hand, if it is indeed a rod knocking, are you willing to drop a grand minimum into it ? On the other hand I once saw a caddy with a cracked flex plate that made a noise you would have bet your firstborn was a rod knocking:eek: A stethoscope would reveal that. In a pinch, a piece of heater hose held to the ear will work ;)

[Michael VII LSC/SE]

A less precise tough still effective, long metal rod or screwdriver held to the skull at the base of the ear or over the ear does well at isolating the specific area.

[hypostang]

Thanks guys I tried the "long screwdriver " trick
problem is the thing is SO noisy it's tough to determine exactly where it is coming from.
Standing outside the truck it sounds like a lifter or rocker arm,
In the driver seat it sounds more lower endish.
My advice to him at this point was get some "stp/motormedic / thick stuff " and keep driving it until it stops .
I figured if we were to tear into it it was going to get expensive fast
and seeing as how it is running fine .........leave it alone until he HAS to spend money :eek:


I am now washing my hands of it until he needs my engine crane :D

[Drake_tr7]

"and seeing as how it is running fine .........leave it alone until he HAS to spend money :eek:


I am now washing my hands of it until he needs my engine crane :D "

He's evolving ! Isin't that cute ? ;)

[bubbaD4life]

i don't know about the coil over plug straight 6 but, couldn't you also unplug the injector to kill power to one cylinder. i know that with age and wear those 4.0 rocker arms start to make noise. on the non-coil over one you can take the valve cover off and check the rocker arms and push rods for wear in an hour or 2, and is real easy. and if you didn't know the 4x4 model takes 6 quarts of oil where the 2 wheel drive only takes 5, at least on a 98 that is.

[Night Wolf]

What exactly kind of noise is it making? How many miles on it? The 4.0 is quite a durable engine....

I would advise NOT to use the fixall-in-a-bottle stuff.

Any check engine light codes?