Hey mechanics???????????????????

[bboswell]

1982 Jeep
4.2 I-6

Ran great last weekend on a couple of trips to town. I got in it this weekend to make a run and it was missing terrible, so bad I never made it to the road...just pulled it back into the shop.

Changed plugs, wires, cap, and rotor with no change.

I did a cold compression test (engine not warmed up prior) and got between 125 and 135 psi on 1,2,3,4,& 6.......and only 5 psi on #5.

How does this happen while it is sitting in the shop? Seems like the sort of thing that would pop up while you were driving to me.

Where do I start now....stuck valve? broken valve spring? Broken ring?

[Kdub]

check your valves and lifters. You might one stuck open.

[Dale Moser]

Do it smoke?

[bboswell]

Only when it drinks!

No smoke. I put a new long block in it about 15,000 miles ago, it has used oil at a rate of 1qt per 1000 miles or so every since but has never smoked or fauled plugs.

Come to think of it, I put some "Restore" engine treatment in it about 50-60 miles ago to see if that would change the consumption............think that could have gunked up a lifter?

[Dale Moser]

Yep, I'd say lifter or valve spring.

[Shiner]

First, You must pull the valve cover to inspect valve movement, broken spring, or push rod that poped out. If it happened that fast, then my bet is busted spring or push rod out of place . I would not run the engine a whole lot, if it is a busted spring, Your running the chance of the valve keepers coming loose and swallowing a valve..... then You will be buying another long block. Once You pull the cover, I'll bet You can see your problem

[whitetailfanatic]

rings on #5?

[wacm]

might of jumped time. obviously not while it was just sitting there but shortly before you shut it off or when you cranked it up. im no mech. but its a possibility. good luck. let us know.

[Jaspro]

Transmission?

Inside joke for those that know.

[Seemore]

I would pull the valve cover first, then if no trouble there. As per Jaspro it could be the Transmission.

Then just kick it, that helps sometimes

[super sport]

oil treatments can cause problems at times sounds like yours problem is in the vavle train, lifter could be stuck,I would look to make sure a vavle is not stuck open you will have to take the valve cover off to see these problems. let us know what you find.

[sitn_on_20s]

Stang_j_99 just got done rebuilding an inline 6 in his 91 jeep.....he's a mechanic...maybe he'll chime in....or pm him.
Heath

[stang_j_99]

Sounds like some of the guys have the right ideal, if it were me i would pull the valve cover and look closely at the springs. Look for one to look like its "double stacked" or broken. Then pull your rockers off and inspect them and the pushrods, to be bent/broken on cyl#5. If one of the two valves don't open then it will have low compression, or if they dont close same thing. Most cases of blown headgasket there will be 2 cyls. next to each other that have low compression. Also you could have a burnt valve or seat that is badly worn. I would say that you prob. is more than likely in the valvetrain. If you need to pm me.

Jason

[stang_j_99]

O btw if you can get ur hands on a cylinder leakage tester (you'll have to use a good air compressor to do this test because of the cfm used) thats the best and easiest way to check compression problems. It will tell you if its the ring or the valves.

[Walker]

First thing to check is all the vacuum hoses.