Camshaft Replacement

Hi all,

My Jeep (258 i6) has a pretty annoying lifter tick and I wanted your opinion on how to fix the issue. I’m pretty sure it is the hydraulic lifter because I pulled the valve cover off and the pushrod and rocker arms looked okay. I have already tried a quart of MMO but it did not help. The Jeep hasn’t been on the road in 6+ years so I can’t put any miles on it to see if it will just go away. I replaced 1 hydraulic lifter about 3 months ago and that was a pain in the butt.

My options are:
1) replace the cam, timing chain and gears, and the hydraulic lifters all at once
2) replace just the bad lifter
3) Get the Jeep on the road and run it till something breaks or the noise magically goes away.

I’m concerned that if I just replace the one lifter than another one will go bad in the future and I will have to do the whole process again. I also read that I shouldn’t replace all the lifters without replacing the cam as well.

I also don’t know how hard it is to replace a cam with the engine still on the frame (I don’t have access to fancy tools to remove the engine). And I also don’t want to mess something up like kicking a cam bearing off the engine and causing myself another issue that I don’t have the tools or expertise to fix.

What do you guys think? Thanks in advance.

 

Send it! Slight ticking noise(s) is made by 90% of all 50yo engines. That's a lot of work to not know if it will even fix the noise.

 

What did the bottom of the old lifter you replaced look like ?
Did you pull and look at any of the others ?
I think you should pull apart, clean and inspect all of the upper valve train components first
before you jump into that cam replacement.
Otherwise, drive it and put some miles on it first.

 

Good advice from Jim (jpflat2a).

Note that you can use all-new lifters with an old cam, as long as the cam is not damaged. One or all, your choice. New lifters, old cam: ok. New lifters, new cam: ok. Old lifters, new cam: not allowed.

A lifter tick should go away as the engine speed goes up, providing more oil pressure.

Have not done it, but you should be able to remove the cam shaft from the front of the engine with it in the chassis. Suspect you will have to remove the grille for clearance.

 

Yes. My old GMC six had a bad lifter that fixed itself - after about two years. Glad I didn't rush into anything.

 

Good suggestions. The lifter I pulled out before had a hole in the bottom of it where it meets the cam lobe. A legit hole, probably an 1/8th inch diameter. Is it normal for old lifters to be used so much that they have a hole in the bottom? If that was related to a bad cam I can give a shot at fixing it, but I really don’t want to. I like the suggestions of just running it and see what happens.

 

Boy. I may be mistaken, but I'd think a hole in the lifter would be the end of the line for the cam and the lifters. How many miles does this engine have? How was it treated? Unless the engine has a bazillion miles, this suggests to me that the PO never changed the oil, or that there was an issue with just that lifter, or something else drastic. Even if it's the lifter that failed, I would expect it had damaged the cam lobe too.

You could run it, but I would take it apart and inspect all the lobes, lifters and cam. if you take things apart, keep the order straight. Valve train parts have to be new or go back in the exact same place in the engine.

 

My family has had the Jeep since it was new. It was used to take boats from storage and launch them in a lake just behind their Marina. It was suggested that because the Jeep was started and stopped so frequently and it never got up to temp, that it caused problems. It previously had the cam changed (or at least that is what I’m told)probably 10 years ago. It has a total of 18k miles on it.

 

Well, this information changes the picture.
Time to pull the engine down.
As mentioned by Tim, there has to be some abnormal wear on the cam lobe that the bad lift rode on.

 

Do you know of any detailed write ups on changing the cam with the engine on the frame. My only worry is knocking off a cam bearing when trying to put a new cam in. I’m not sure how to support the cam when it slides in if I can’t reach inside the engine.

 

You just wing it being careful the whole process.
A factory manual might describe the exact process.
But you're going in and out of a blind hole.
You have to go by feel.
(No crude jokes to be inserted here please)

 

Lol. Perfect! Thanks for the input guys.

 

i have not done this but looking at the TSM - it says the bearings are stepped in size to allow easy insertion of the camshaft. The bearings are also pressed in, so you should not be able to push them out unless you bang them repeatedly with the camshaft. There are threaded holes in the front of the cam. You could thread in a long bolt, or thread a rod, or make some kind of a handle to tilt the far end of the cam up when you insert it, as needed. The camshaft gear attached to the cam may give you enough of a handle and leverage to lift the far end of the cam.

 

you will need to pull the radiator and grille for enough length to get the cam in and out.