OK....here we go...cam removal without pulling the head or the lifters!
I know what you are thinking - it isn't possible, right? Wrong!
Why would you want to do this? First of all, pulling the head is a huge PITA...second of all, my engine only has 12,300 miles on it, and I'm not worried about mixing the cam and lifters as conventional wisdom would have you believe. I've put new lifters on old cams with no issues, so to me the reverse should be true as well - especially if the miles are low.
I'm going to skip some basic steps, so this first picture is just after I removed the fan, fan shroud and radiator. I also had the valve cover off at this point as well.
In this next photo, I lifted the entire grille shell with the condenser attached to it and set it aside. Needless to say, I already had the A/C discharged, so it was fairly easy to just unbolt the lines at the connector block and plug them up.
Naturally the next couple of steps were easy too - they involved removing the belt and the tensioner. I then pulled the crank damper and set it aside.
This picture shows what I did next - I removed all of the rocker arms and spark plugs and pushed them into a cardboard "thing" I made to keep them organized and in order from front to back.
So now we arrive at the point where I'm pretty well committed - no turning back now. Timing cover coming off...
Removing the cam sprocket and chain was the next step and a cinch, so no picture...however, with the sprocket out of the way we now have access to the main oil gallery. Here's a shot of me pointing at the hole and "special tool" I had to use to get it out. It's a square drive, but it's not 1/4" or 3/8", so we made do with what we had.
So here's where it gets tricky - I'm ready to insert the dowel into the oil gallery/rifle bore, but the 3/8" dowel I bought (as recommended by the guy who told me about this trick) was way too big. We ended up using a 5/16" dowel and even that was a snug fit.
The guy who told me about this trick also told me that all you needed to do was rotate the cam and push the dowel in under each lifter as the cam lifted it.....ummm, yeah...not so much. I'm not sure if he was intending to support the lifters via the chamfer cut into the lifter body that allows oil to feed into the center of the lifter. We tried an even smaller dowel (I want to say 1/4") but it pushed right in with no resistance, so I wasn't getting a warm fuzzy feeling about supporting the lifters via the chamfer.
The safer play was getting the lifter up high enough to slide the dowel underneath of the lifter foot, so there was no way for it to fall into the oil pan with the cam out. Here's what it looks like with the dowel all the way in:
It took a lot to arrive at this point - I won't lie. We had to manually (and carefully!) lift each lifter up out of it's bore with a small hook fabricated from some welding wire. It's not easy, but you can engage the inside groove cut into the lifter that the circlip snaps into. Google a hydraulic lifter exploded view if you can't visualize what I'm saying since I can't think of another way to describe it.
When lifting the lifters up, you have to be really careful - if you lift too high, the lifter can come out of it's bore and flop over on it's side....we actually has this happen to us on the 3rd or 4th lifter from the front, and somehow my buddy helping me managed to tip it back upright and get it back in it's bore - don't ask me how he did it through that tiny pushrod hole, but he's my hero!
So now we arrive at the moment of truth - sliding the cam out and praying that we don't hear the sound of lifters falling into the pan!
In this picture you'll also see the clever cam "handle" fabricated by the guy who has done this before. it really helps to stabilize the long (and heavy!) cam as you slide it out:
In this next shot, the cam is almost all the way out:
We decided to take a shot down the cam bore so you can see that the lifters are all clear of the cam:
Pretty cool that you can see all the way to the back of the block - look Ma! No lifters!
The good news was that other than the OPDA drive gear in the cam, there was no unusual lobe wear of any kind on the cam...so, the logical extension of that is that the lifters should be fine too. Heck, with 12,300 miles on it, one would hope so!
So, now it was time to put the new cam in. I lubed up the journals with some lubriplate since they get direct feed pressurized oil, so I wasn't worried about stress on these surfaces.
A few weeks before I decided to embark on this project, I stumbled across a cam lube from the same company that makes the ZDDP additive. They have all sorts of pictures and charts on their website comparing their product against other cam lubes that seemed pretty convincing, so I decided to give it a whirl.
The upside is that this stuff is nice and thick, so it definitely stays in place, unlike some of the other lubes that are more like a thick gear oil:
So, now the cam is in and I've installed the thrust plate to make sure it isn't going anywhere when I slide the dowel out:
Now it was time to slide the dowel back out - note that I had the pushrods sitting in their respective lifters so I could watch each one drop as the dowel slid out:
Note the height of the pushrods towards the front vs. the ones at the rear....
As you do this, you'll hear each lifter drop down onto the cam - a satisfying "click" lets you know all is going well.
So from here on out, there are no pics - it's pretty much just put everything back that you tore off to get this far. Some tips along the way:
- Don't guess about how tight stuff should be - use a good torque wrench and follow the specs in the manual.
- Remember to put some thread sealant on the gallery plug before installing it
- Use RTV at the joint where the block meets the oil pan to ensure the front cover seals properly
- Make sure to install a new OPDA gear to mesh with your new cam - don't want to ruin all that work!
- Put some break-in concentrate in the oil to ensure the cam breaks in properly
- After buttoning everything up, adding coolant etc - get ready to fire the engine up - you're almost done!
- Fire the engine up and try to keep it above 2000 RPM for 20 minutes or so. Have an assistant listen for any noises and look for leaks
After the break in, make sure all your fluid levels are OK and enjoy your freshly repaired Jeep. Chances are you will have a code for cam/crank sync (P0016) - ideally you need to have access to a DRBIII service tool to properly set the cam/crank variance and initiate the relearn procedure. A dealer can do this for you, for a fee of course.
Next steps: sometime in the next few weeks I'm going to have the A/C recharged and I'll pop the OPDA out again to see how things are looking...I'm keeping my fingers crossed!