my check engine light came on and said that cylinder 4 had a misfire. checked the compression on it and it was 60 pounds. all the others read above 150. so i put a little oil in the cylinder to see if it was the piston or the valves. the compression jumped from 60 to 90 pounds with the oil sealing the rings up a bit, maybe. just a guess. so that being said, should i pull the head off and see if the cylinder is scored? and if it is what are my options. or should i just go to the yard and get one off another truck and swap it in?

 

Need to find out where all the pressure is going. Seems your rings are already questionable though..... did you test any other cylinders wet? A comparison there would be good.

If you can, do a leak down test. Or, if you get the same major jump in pressure on the other cylinders, gonna be time for a rebuild in any event. If you can't do the test, yank the head. Have a look, take it from there.

If the cylinder is scored, you are going to have to pull the motor, tear it down, hone the cylinders, and replace the rings. (provided the scratches aren't TOO deep....) You could conceivably do it with the engine still in the truck..... but, it is FAR easier with the engine out. You could even potentially do it in the truck, and just do the one cylinder........ Since the others seem to be pretty good....... Not my preferred choice, but, if you are operating on a limited budget, well, ya do what ya gotta do.

 

well thanks hey you. your good help on here just to let you know, you always answer and have good info. would it be cheaper/easier to just swap in a whole new motor?

 

If theres significant damge to the motor, probably better off going to Mopar and get a complete new engine. They do come with warranties. I would stay away from getting a used motor locally or from anyone as people don't take care of there equipment. I learned the hard way and won't do it again. Plus, you have no warranty.

 

Thank You. I like this place, and the people herein.

It would certainly be faster to swap in another motor.... If you can, do the leakdown test, and see what the results of that are. If it does indeed indicate the rings are toast, yank the head anyway, and have a look at the cylinder wall... If it is looking pretty bad, a new engine just might be in your future.

A lot depends on what your budget looks like, if you have an alternate vehicle to drive, and a place that you can work on it. If you need rings, and have to pay someone else to do it..... it might indeed be cheaper to just slap a new motor in. There was a thread on here not so very long ago about a company that sold motors (longblocks) for our trucks for under 1500 bucks. Not including shipping and any applicable taxes mind..... I don't think.... That would have the advantage of yank the dead one, slap in the new one, and be done with it. And, it would have that 'new motor' smell.

 

welcome to a few days/weeks of torture.

the decision you are left with just plain sucks.

what do you do? do you trust another person who says 'motor runs just like new'? seen it a bunch; people buy wrecked trucks for parts and just lie about what they have left over.

when i replaced my jeep motor i had a hell of a time; do a stroker, v8 swap, or trust a miled out 4L? i got one off a buddy in my local jeep club that people i trust have seen run, driven the vehicle etc. for now its running ok.

neighbour has the same issue as you right now......

i'd suggest, especially if you have another set of wheels to get you around, pull the heads off it and take a look. it could be something as simple as bad valve killing compression, or something similar.

i'd start with a leakdown. see how bad it is in all cylinders.
if you get bad numbers on other cylinders tear it down. could be something simple; could be something bad. only one way to find out.

or drive it till it explodes...........