PatHenry

Ok, so I'm gearing up to do a tune-up on my 95 and as it's been about 20 years since I've dealt with an engine that has a distributor, I have some 'stupid questions':

1 - It appears that the rotor just pulls off - is this true? Is there anything I have to worry about putting the new one on?
2 - While I'm messing with the cap and rotor, I figure it's a good time to check the bushing. Is this as simple as trying to move the distributor shaft by hand? There should be no movement or play, right? Is there anything else I should be looking for?
3 - Since I'm removing plugs anyway, I'm thinking I'll do compression testing so I have a better idea of the state of the engine. (To be followed by lab testing of the oil)
All the general instructions for this indicate disconnecting coil and fuel and turning the engine over with the starter is the proper procedure. Is this the recommended practice for the 4.0 or is there a better way to do this (manually or something like that...)?

I already did the O2 sensor - which was a personal victory as I'd tried a couple O2 sensor replacements in the past and could never get the old one out.

Any advice is always welcome.

cruiser54

You got it. I just unplug the CPS when cranking it over for a compression test.

You doing plugs, wires, cap and rotor?

PatHenry

Yes sir! I have a Mopar tune-up kit on order and I've got a set of Champion plugs gapped and ready to go. I replaced my O2 sensor with a NTK a couple of weekends ago.

My XJ runs great currently, I just want to do the tune-up since I don't know when the PO last did one. I've got the tune-up and radiator flush/HCV elimination on my maintenance list that I've slowly been going through.

I'm doing the compression test and then lab analysis since I want to get a good idea of how solid the engine is. I originally bought the XJ with the intent to drive it for about 2 years without putting a ton of money into it with the hopes of being able to afford a new 2019 or later JL by the time the XJ dies. However since then the MPG ratings for the JL 6cyl-6spd came out and were disappointing. Even with all the highly touted changes to improve MPG, the JL only gets like +1 city over the JK and a brand new JL gets about what an XJ gets. And since the diesel option is not going to be available with a manual tranny, my original hopes of being able to get back to having a DD Jeep are not looking great. (I have young kids so my DD needs to be extremely reliable without killing me at the gas pump. - And having 4 doors is not an absolute requirement, but it's pretty close)

Therefore I figure that if the engine is in good shape and I can reasonably expect to drive the XJ for 4 or 5 years (as a secondary vehicle) without the engine failing, it may be worth it to put more money into it. According to the PO the engine had about 150k on it, so roughly 158k now - so it's possible it's barely broken in, but I won't know the truth until I do some analysis.

The big money things on the horizon are the leaf springs and clutch. The leafs are saggy, but not bad enough that I have to do them now-ish and the throw-out bearing is noisier than I'd like but not so much so that I need to do it now-ish. So if the engine passes the "new requirements", I can justify putting $400 and a weekend into leafs/shackles/hardware/shocks and then $2-400 and another weekend for the clutch/flywheel/spacer plate/CPS. And, of course, also handle any of the many things that can pop up going forward.

PatHenry

Just to follow up on this post -

I finished my plugs, cap/rotor/wires and compression testing.

Compression was all in spec on my 24 year old engine.
Distributor was nice and tight.
Old plugs looked right where they should for normal wear.
The old plug on cyl 1 was so loose I did a double take as it came out by hand. The plug wire on cyl 6 had the boot clip thing break off when I removed it.

The Jeep runs noticeably better - noticeable, but it ran pretty well previously.

So I'm waiting on my Blackstone Lab analysis and with hope will be starting my major fix list soon.

Ralph77

I have been living in ignorance for about 5 years now and figure I should get a handle on where the engine in my '00 stands. So I am about to do the same. Oil analysis, compression test, etc.

My understanding for the compression test is I should pull all the plugs, pull the fuel relay, and press the gas pedal to the floor when doing the compression test. Should I unplug the crank positioning sensor too?

PatHenry

Disconnecting the crank sensor should prevent fuel and spark.

When I did mine I disconnected the ignition coil wire to the distributor and pulled my fuel pump relay then ran it until it stalled- just because it was easier to get to than the CPS.

As I mentioned, the reason for the testing for me is that there are several major $$ and time consuming items that my XJ needs in the near future (plus a ton of little things that aught to be done) and for me personally, if the engine dies on me - it's almost certainly the end of the vehicle. I don't have the time, knowledge or experience to get into major engine repairs, nor do I have a good place and the equipment that would be required. On top of that, as I live in the North-east, we have rust - and while my XJ is in pretty good shape at the moment, it would be hard to justify the effort to swap out even a complete junkyard replacement into a body that already has rust. I love XJ's and would happily drive the one I have for the next several years, but I don't want to dump a ton of money into my XJ to do so - so it's vital to me to know (as much as can reasonably BE known) what condition the engine is in.

Ralph77

Now that is one thing I did not think of. Run the Jeep after pulling the fuel relay to get that last bit of fuel out of the line. Thinking that is a must?

I live in CT. My Jeep is in good condition. I don't want to buy another one. See how I have an '00, with the 0331 head, I have been talking to my buddy about building me an engine. He is not a Jeep guy but is a car guy and says he can do it. Has killer garage too. I picked up a TUPY head awhile back for $50 on Craigslist. Could be usable or rebuildable. Could be a door stop. Now I believe everything to be in good shape. But figure should do all the tests to find out. If all is good maybe I will have the head checked and at some point maybe install it. If the engine tests turn out to bad then an rebuilt engine she will get.

PatHenry

I was surprised how long it ran without the fuel pump relay. I was expecting a couple seconds -fire up and die and it was several seconds (maybe like 7-10) before it totally purged the fuel from the system.
I think the running out the gas is important because I didn't want a bit of unburned gas getting into my oil.

My XJ actually came from CT - I wanted an I6 with the AX15 and it had to run and drive and have functional 4wd - which it did. The seller was a young guy and he said the drivetrain was swapped out of a 94 XJ and had 150k on it (the Odo was 295k) because he ran the old engine without oil. He seemed like a good kid, honest and clearly loved the Jeep. I think it was his first vehicle. He seemed mechanically inclined as he talked about it like he and his Dad and friends did the work themselves. (One of his friends had a seriously jacked up - at least 4-6" - XJ)
However, as I only have his word - I make no assumptions. I've only had mine for 6 months.

So if I put money into the Jeep, it will only make it that much harder to NOT fix things going forward. If I spend the time and money to do the leafs and clutch, then fix a bunch of the little things and then the engine blows, I know I'll have a hard time convincing myself to NOT repair it... LOL.

Ralph77

I have owned mine for 5 years now. Was a kinda running but not driveable deal. But the body, glass, and interior were pretty good. So I decided to take a chance. Got her up running, punched through emissions, and for the most part everything I have done has either been maintenance stuff or adding factory options she did not come with. Have been avoiding checking oil pressure with a mechanical gauge, doing a compression test, etc. Ignorance is bliss and all that. But it is time to find out.

PatHenry

I had trouble finding a loaner tool for the oil pressure gauge, so I just bought the Harbor Freight one. It worked pretty well and confirmed my gauge was reading correctly.

I did use the Autozone compression tester - it was an OEM brand and wasn't well reviewed, nor was it very granular (if you're looking for the exact number), but it did the job for me.

The PO of my XJ was saying that CT inspections on older vehicles didn't have to pass the safety checks (which seemed strange) but did have to pass emissions. Interestingly, up here in the People's Republic of MA, shockingly vehicles older than 15 years don't need to pass emissions, but do have to pass the safety. Apparently, having a steel bar welded to the front bumper mounts is a no-no, but spewing a bunch of pollution into the air is A-ok!

Ralph77

We used to have a 10 year old or more vehicle safety inspection way back when. But they did away with that. Car needs to be 25 years old or more to be exempt from emissions testing I believe.

I am leaning towards OTC for a compression tester, leak down tester, fuel pressure tester, and the oil pressure tester. Stant for the coolant pressure tester. Of course I might just cheap out and go Harbor Freight too. I know this is over the top and the use I will be getting out of these tools is minimal. But I think I want them anyway. My birthday is coming up so I am going to justify spending the money that these are presents to myself. LOL.

PatHenry

Just to follow up on this - I got my oil analysis results and everything is good. So between the good compression results and good oil analysis results, I'm good to go on my major item list.

cruiser54

How did we know this was gonna be the result??????

PatHenry

Because the Jeep I6 is freakin' awesome!!!

It definitely was the hoped for and expected outcome. However, like I mentioned, I definitely DON'T want to be dealing with an engine failure. My family has had 2 previous Jeeps and both had perfectly running engines after 305k and 400k, but both of those were bought brand new and well maintained throughout their service lives.
23-24 years is a long time - I wasn't even old enough for my learners permit when my Jeep rolled off the assembly line.

I have to say that I'm extremely happy with spending a total of $28 and knowing as well as can be reasonably known that the engine is in good shape and has no signs of impending problems. What I was primarily worried about was either A) The kid selling me the Jeep never replaced the engine and it had a hard driven 300k on it or B) That there was a minor head/block leak or fuel injector leak that wasn't so bad as to show signs of the problem, but had been slowly destroying my bearings. There are so many threads on here about fuel injectors it definitely got me a little paranoid.

I've spent a bit less than $2k on my Jeep - about what I had planned to when my plan was to get 2 years of occasional driving. I have the leaf springs, clutch and exhaust manifold on my major repair list which is roughly $1k just in parts. I've got plenty of other things that I could spend $1K on, and now that I'm confident in the engine is good I'm confident that it's worth putting that money into the Jeep.

cruiser54

And now you owe us all a beer for saving you so much money.........