2012 Liberty No compression on cyl 6?

[slingworks]

I'm looking at a 2012 Liberty that's got some issues with compression on cyl 6.

It's around 150k miles, fairly well babied and fairly clean overall.

The owner did a compression test and all cylinders are good except for 6, that has no compression. They said it just died on the road and it will start and run with a serious miss if you keep some throttle oni t.

I'm thinking to pick it up as a project. Wanted to listen to it a little so we started it up. Started fairly easily, but with a heavy deep miss and some shake. Sounded pretty good considering. No knock, rattle or otherwise. was pretty quiet overall.

The owners put new coils on it before pressure testing, thinking maybe was a dead coil.

I'm not sure what to think. I don't think a valve dropped considering it's not making any noise. No popping as in a bad lifter and no crazy imbalance clatter or vibration like a broken rod. Didn't burn any oil and the oil looks good as does the antifreeze. So I'm thinking no piston/ring damage and probably not a bad head gasket......

What is a good guess? Could a lifter collapse or rocker come off and cause a no compression situation?

 

[24turbo]

Broken valve spring.

Bought a 2008 a few years ago with exact symptoms….easy and cheap fix.

 

[michael mehle]

I'm looking at a 2012 Liberty that's got some issues with compression on cyl 6.

It's around 150k miles, fairly well babied and fairly clean overall.

The owner did a compression test and all cylinders are good except for 6, that has no compression. They said it just died on the road and it will start and run with a serious miss if you keep some throttle oni t.

I'm thinking to pick it up as a project. Wanted to listen to it a little so we started it up. Started fairly easily, but with a heavy deep miss and some shake. Sounded pretty good considering. No knock, rattle or otherwise. was pretty quiet overall.

The owners put new coils on it before pressure testing, thinking maybe was a dead coil.

I'm not sure what to think. I don't think a valve dropped considering it's not making any noise. No popping as in a bad lifter and no crazy imbalance clatter or vibration like a broken rod. Didn't burn any oil and the oil looks good as does the antifreeze. So I'm thinking no piston/ring damage and probably not a bad head gasket......

What is a good guess? Could a lifter collapse or rocker come off and cause a no compression situation?

I have an 07 with the same story. The slight miss while waiting at a long light sets off engine light. I either put in neutral at the time or just clear the light when I get home. 6 yrs and the only issue...

 

[24turbo]

I have an 07 with the same story. The slight miss while waiting at a long light sets off engine light. I either put in neutral at the time or just clear the light when I get home. 6 yrs and the only issue...

?????

This isn't a slight miss. Its will start but runs horribly (probably to the point it cant be driven).
As described by the OP this isn't the same at all.

My step-sons 2011 Ram did the same thing, but it was a 5.7 hemi. He took to the dealer and they said it was the cam worn out (great diagnostics) and "just replace the engine". I fixed it for $10.50 for a new spring and about and hours time.

 

[slingworks]

?????

This isn't a slight miss. Its will start but runs horribly (probably to the point it cant be driven).
As described by the OP this isn't the same at all.

My step-sons 2011 Ram did the same thing, but it was a 5.7 hemi. He took to the dealer and they said it was the cam worn out (great diagnostics) and "just replace the engine". I fixed it for $10.50 for a new spring and about and hours time

I bought the jeep as a gamble/project

You know what? I took the valve cover off and discovered a broken intake spring. I had thought the worst really. Surprisingly it would actually stay running/idle with the plug out. I guess it was "injecting" a mix of poorly burnt exhaust gas back through the intake manifold! With the plug out it was venting most of it to the atmosphere....

As loose as the keepers were on the stem, I'm amazed we didn't lose it trying to get it to move under power.

I guess a little inflation, a spring cost me about $11! LOL. The valve seal needs changed a well, I guess it didn't handle the situation too well? I have a pack of them left from a 6 year ago project. I also bought a miller valve spring tool and a compressed air adapter on ebay, so will probably be the weekend before I tackle changing it.

I don't know what it takes to wear down a cam on a 3.7, at least the 05 and up. My mail jeep is a KJ and as many miles as I'm put on it, the cam lobes show no wear at all. (Just put timing chain kit on it) Almost feel like that's a "diagnosis from before our time?

I kinda like this KK. more than I thought. Black with "leatherette" seats. Bought it before I saw your post, but turned out you were right.

 

[24turbo]

I bought the jeep as a gamble/project

You know what? I took the valve cover off and discovered a broken intake spring. I had thought the worst really. Surprisingly it would actually stay running/idle with the plug out. I guess it was "injecting" a mix of poorly burnt exhaust gas back through the intake manifold! With the plug out it was venting most of it to the atmosphere....

As loose as the keepers were on the stem, I'm amazed we didn't lose it trying to get it to move under power.

I guess a little inflation, a spring cost me about $11! LOL. The valve seal needs changed a well, I guess it didn't handle the situation too well? I have a pack of them left from a 6 year ago project. I also bought a miller valve spring tool and a compressed air adapter on ebay, so will probably be the weekend before I tackle changing it.

I don't know what it takes to wear down a cam on a 3.7, at least the 05 and up. My mail jeep is a KJ and as many miles as I'm put on it, the cam lobes show no wear at all. (Just put timing chain kit on it) Almost feel like that's a "diagnosis from before our time?

I kinda like this KK. more than I thought. Black with "leatherette" seats. Bought it before I saw your post, but turned out you were right.

The engine with the “worn out” cam was a 5.7 hemi in a Ram1500. Cams are a common problem with them but the dealer just assumed it was the cam and charged my step-son $300 to diagnose and probably never laid a wrench on it to confirm….Just spend the $13000 on an installed mopar rebuilt hemi. Gravy job for them.

Awesome you got yours running again.

Funny thing broken valve springs are so common!