bigmistake's 91 MJ - Project ELi5

[bigmistake]

Hey everyone!  I joined about a year ago with the forum post "Should I buy a Comanche?" - it has been a long bit of searching, but I finally ended up with one!  I looked at quite a few, but I really couldn't bring myself to buy a rusted out vehicle that needed tons of work.  I have never worked on cars - I've always wanted to - so a truck that is barely operating sounding like a lot to take on to start with.  I stumbled onto this truck, picked it up from a great guy, and it is letting me hit the ground running.  I plan to do everything myself where possible - it won't be my DD, so it relieves a little pressure there.  I'm hoping to learn as much as I can as I go - hence the project name!

 

I really have no clue what I'm going to do with it... hopefully the forum will have some ideas.  My first goal is to get everything running the best it can and refreshed as much as possible (it has been sitting for a while).  I haven't pulled back the carpet to check the floors, but everything else is rust free... shockingly so.

 

The truck runs, has AC that blows (but doesn't blow cold), is rust free, mostly straight (it looks like the front had a collision that warped the front bumper mount area... I will post a picture).  The suspension definitely needs some work - I can push on the front bumper and watch the truck rock back and forth for what feels like a minute!

 

Overall, I'm really excited to finally have a truck again, especially one as awesome as an MJ!  It is also my first Jeep!

 

Currently: 1991, 2.5l, AX5, 2WD, SWB

 

 

 

Here are some initial thoughts, and maybe people can steer me one way or the other on where I should get my mind:

- I'd like to use this truck for all of my outdoor sports (fishing, hunting, camping, etc).  With that in mind, I'd like to eventually swap it to 4x4.  I've never owned a 4x4 vehicle, so I'm kind of curious what else I should do to it while getting it prepped for my purposes.  I know a lot of yall throw massive lifts and huge tires onto these trucks...  How much lift and tire size should I be thinking about?  I don't really want to get into rock crawling or anything extreme - my purposes will likely be limited to the above, with any wheeling going into getting from A to B.  (Most of my 4x4 will likely end up on the beach or getting through muddy trails).  Given that my suspension needs an overhaul, I think the lift might be the first thing I work on.

- I'd like to find a good shell for it.

- My engine currently has 200k miles on it.  I plan on driving this until it quits... then maybe doing the massive overhaul to the 4.0 - or maybe something else?  After driving the little 2.5l, I've been pretty happy thus far (of course, it is a new vehicle to me, and it feels great to be back in a truck, and MJs are just awesome... so maybe that is playing into it).

- I'd like to clean it up, get rid of any cosmetic problems, and get it painted at some point... but that is way down the line, I think.

- Any updates/upgrades you view as essential I should look at doing?

 

Thanks for reading!

[kryptronic]

Welcome to the club!  There aren't many of us with HO MJs, so we stick together.  My number one suggestion to you is to always note that you have a HO when posting in tech.  And take pretty much anything HOrnbrod says regarding the HO as gospel.

 

That 2.5L is a great engine and could outlast you, with proper maintenance.  For the light trail driving you intend on doing with it, you may even prefer it over a 4.0L.

 

You might want to look at a small 0-2" lift with 31s for your intended purposes.  Anything bigger tire-wise, and you will want to swap in a 4.0L.  However, at stock height with 235s, I think you'll find the truck perfectly capable.

[bigmistake]

Thanks for the info!  I think a 2" lift sounds pretty good.  I spent the evening skimming through the forums and looking at lifts + tire size threads and photos, and 31s with 2-3" lifts look great to me.

[bigmistake]

Not much in the way of changes since I've had it.  This weekend I removed all of the decals, took off most of the front end and put it back together.  There is some crookedness from a past wreck that I'm wanting to correct.  It was also a nice excuse to wrench on a vehicle for basically the first time.

 

 

I had a vacuum canister that the previous owner had left in the cab.  He said that the previous owner before him had purchased it to fix his AC...  So, I tracked down where it should go and found a hard plastic line with duct tape on the end.  I'm going to pick up some hose and get things connected.  There is also a slow oil leak on the valve cover.  I searched around town and nobody had a replacement gasket for the 2.5l, so I've got one ordered.

 

Next up: valve cover gasket, vacuum canister, fluid change... then a LOT of hauling things out of my yard and garage to clear up some space.  And trouble shooting why the AC won't get cold (I know the compressor won't turn on, but I haven't really dug in yet).

 

Future plans:  I found a 4x4 donor with matching gear ratios!  The problem is, transfer case is missing off of the transmission.  I'm debating finding an ax15 + transfer case to swap over to...  based on my research, that would require a bellhousing, pilot bushing, and clutch disc to get it to mate up.  We will see.

[bigmistake]

Progress!

 

I replaced my valve cover gasket, hooked up my vacuum canister, and did my oil change.  So, as I've mentioned, this is my first time working on cars...  I thought the valve gasket would be pretty straightforward for a first project (and it goes hand in hand with the oil change, so worked out). 

 

While removing everything touching the cover, I bumped the heater hoses.  The heater control valve immediately exploded!  Coolant went everywhere and I was left staring at a mess.  After going through the parts manual I was finally able to figure out what the part was (I had no idea).  A quick search on the forums let me know that everyone universally despises that part and that I should just delete it.  SO - I no longer have the heater control valve!  There was a little white wire/line connected to it that I'm unsure what to do with... I just left it dangling.  If anyone knows what I should do with it, let me know!  I may have to post in the other subforum.

 

I had also noticed my coolant was low before this, so I rented a pressure tester.  Turns out my cap was bad so I replaced that.  I haven't flushed the coolant, but I should probably do that since the truck has been sitting (I'm not having overheating problems or anything, just feel like it would be a smart move).

 

One thing I noticed from removing the control valve is that my truck blows hot air now.  My AC doesn't work (no clue why), so I'm guessing since no cold air is blowing it is opting for hot air.

 

It might not seem like much, but that is the most work I've ever done on a vehicle, so it is a good start!  I took the truck for a spin and let it idle in the driveway to check for leaks.  All looks good so far.

[Minuit]

3 hours ago, bigmistake said:

Progress!

 

I replaced my valve cover gasket, hooked up my vacuum canister, and did my oil change.  So, as I've mentioned, this is my first time working on cars...  I thought the valve gasket would be pretty straightforward for a first project (and it goes hand in hand with the oil change, so worked out). 

 

While removing everything touching the cover, I bumped the heater hoses.  The heater control valve immediately exploded!  Coolant went everywhere and I was left staring at a mess.  After going through the parts manual I was finally able to figure out what the part was (I had no idea).  A quick search on the forums let me know that everyone universally despises that part and that I should just delete it.  SO - I no longer have the heater control valve!  There was a little white wire/line connected to it that I'm unsure what to do with... I just left it dangling.  If anyone knows what I should do with it, let me know!  I may have to post in the other subforum.

 

I had also noticed my coolant was low before this, so I rented a pressure tester.  Turns out my cap was bad so I replaced that.  I haven't flushed the coolant, but I should probably do that since the truck has been sitting (I'm not having overheating problems or anything, just feel like it would be a smart move).

 

One thing I noticed from removing the control valve is that my truck blows hot air now.  My AC doesn't work (no clue why), so I'm guessing since no cold air is blowing it is opting for hot air.

 

It might not seem like much, but that is the most work I've ever done on a vehicle, so it is a good start!  I took the truck for a spin and let it idle in the driveway to check for leaks.  All looks good so far.

 

The heater control valve usually breaks the first time someone accidentally touches it, so don't feel too bad. I think I got about a year and a half in before I touched mine and broke it 

 

That white line is a vacuum line - plug it, or else you'll have a vacuum leak.

 

Flushing the coolant is never a bad idea. Do know that you'll have to work with it to get air out of the system when you refill it. My "technique", such as it is, is to squeeze the upper radiator hose while I'm filling the radiator, and once that doesn't make any more room for more coolant, start the engine to allow coolant to circulate through the system. Keep squeezing the upper hose and filling until you can't add any more coolant to the radiator. Once you're confident you're done, then fill the overflow tank to the fill line. Doing it this way has never failed me on my own '91, but everyone has their own way. If you don't fill it completely, the system can replenish itself from the reservoir so don't worry too much.

 

Removing the control valve will cause a slight increase in the cabin air temperature. The engineers did put it in for a reason, after all. I don't know if anyone has any before/after measurements to see just how much effect it has, but there will be some. Do make sure that your blend door (the thing that switches from hot to cold air) is working fully. Look under the center of the dash from the passenger side, and as you move the selector from cold air to hot air, you should see a little arm rotating. If I remember correctly it should have a little under 90 degrees of travel. They can get cranky sometimes, and this would cause you to have hot air all the time in the cab.

 

 

[bigmistake]

Thanks Minuit!  I have been watching videos on flushing the system - yours sounds like the simplest.  I will take a look at the blend door - definitely sounds like it could be the problem.

 

On the AC - I know the compressor isn't spinning.  I swapped relays to see if that would do anything, but it still didn't work.  I need to get a multimeter so I can see if it is getting any power.  I think I also read that if there is no freon in the system it won't spin...

[bigmistake]

No pictures for this post because I was almost immediately covered in grime...  But I put on new shocks yesterday!  I managed to pick up some JK Sahara shocks and the parts needed to mount them, following jerpderp's DIY thread.

 

The highlight of installing these was getting to see how bad the old shocks were.  The rear passenger shock I could compress with my hands, and when I was cleaning up 30 minutes later it was still completely compressed!  I didn't take the truck out afterwards, so I can't comment on the ride quality - but it is definitely going to be an improvement.

 

I had a lot of trouble pressing the new bushings into the shocks, but I remembered a solution I saw somewhere that really helped -  I used a hose clamp to compress one side of the bushing, then pressed the bushing in using a vice.  I tried a ton of stuff before that, this just happened to be the one that clicked best for me.

 

Now, the not so great: I drove A LOT around town with a friend so we could hear the truck get flaky with accelerating...  For the first 15 miles or so, the truck never missed a beat.  After it had been running a while, it started failing to accelerate more frequently.  When we got home, I parked it for a few minutes to re-arrange cars before putting it in the garage, and it wouldn't start.  When I finally did start it, the idle was ROUGH and it kind of felt like it wasn't firing on all cylinders - really chugging and lopsided.  I turned it off and on a few more times and eventually I was able to get it to start and sound normal, but then it wanted to die on idle, so I had to keep my foot on the pedal.  Not sure what that was about.  More investigating is in my future...

[bigmistake]

I replaced spark plugs and wires this week.  It immediately drove better than it had been.  Went to the store, came back out, and it started misfiring again.  I let it sit for a while, started it up, and it was okay again.  I'm going to slowly work through debugging the ignition system.  I'm going to take a look at the distributor cap and rotor next.

[HOrnbrod]

17 minutes ago, bigmistake said:

I replaced spark plugs and wires this week.  It immediately drove better than it had been.  Went to the store, came back out, and it started misfiring again.  I let it sit for a while, started it up, and it was okay again.  I'm going to slowly work through debugging the ignition system.  I'm going to take a look at the distributor cap and rotor next.

 

You have a 91 - check for fault codes. I had symptoms like that and it turned out to be a failing sync sensor in the distributor, code 54.

 

Here's how to do it. 

 

[bigmistake]

Thanks Hornbrod - I didn't even think to check codes since the CEL didn't come on.  I will do that when I get home!

[bigmistake]

Checked, no new codes (12-55).

[bigmistake]

Replaced water pump, flushed coolant, replaced control arm bushings, replaced distributor cap and rotor, new fuel filter, and recharged the AC.

 

I took it for a quick drive to gas up...  Still not running right.  It takes a lot of cranks to get started, then has to sit for a while or it bogs down when I give it gas.  Once I start driving, I almost always get misfires for the first 5 minutes of driving along with sluggish acceleration.  Maybe my fuel pump is on its way out?

[bigmistake]

I was thinking about it and realized I haven't checked codes in a while.

 

I got:

51
O2 detects lean mixture.
Check sensor and circuit and for vacuum leaks.

 

33
Air conditioning clutch relay.
Wiring to A/C clutch fault.

 

---------

 

The AC compressor kicks on and off over and over... so I am guessing that is the reason for the 33!

[bigmistake]

Lots of work this week on the MJ.  Replaced fuel pressure regulator, upgraded to 4 hole fuel injectors, dropped my gas tank and replaced my fuel pump.  Definitely things I've never even thought about attempting on my own!

 

All of this has been working towards fixing the stuttering, misfires, lack of acceleration, and long crank times I've been experiencing.  

 

The fuel pump took me a while (I had trouble working the tank down to the ground), but I eventually got everything back together.  Took a while to start up, but eventually started and the initial test drive was really promising.  I'm hoping it starts right up tomorrow and runs like a champ!

 

Here is a photo of the new fuel pump trimmed and ready to go back in the tank:

 

[bigmistake]

As a follow up - looks like this was the fix!  I've been driving the truck daily since Nov 15th with no hiccups.  I even took it down to visit family over Thanksgiving and it handled highways great.  Now that things are running smoothly, I feel more confident spending some time and money towards more fun upgrades.

[Pete M]

hooray! 

[Swampy]

On ‎12‎/‎10‎/‎2018 at 3:48 PM, bigmistake said:

As a follow up - looks like this was the fix!  I've been driving the truck daily since Nov 15th with no hiccups.  I even took it down to visit family over Thanksgiving and it handled highways great.  Now that things are running smoothly, I feel more confident spending some time and money towards more fun upgrades.

 

That's awesome. More driving than I have done with my driveway queen. Hoping to change that this month

[bigmistake]

Thanks!  I'm not going to lie, it has been awesome.  I'm loving driving this truck!

[bigmistake]

I went to the junkyard this weekend and managed to pull a Dodge Dakota bellhousing for possible future transmission upgrades:

 

 

While I was there, I saw they had three XJs listed.  Here is what two of them looked like:

 

 

 

The third was almost in as bad shape, but I could at least get into it.  I snagged the visors out of it and finally got some in my truck:

 

 

 

Not epic, but slowly making things better!

[Pete M]

6 hours ago, bigmistake said:

 

 

 

 

ouch!   

[Minuit]

Damn.

 

I kind of want to know what happened to it, but on the other hand I don't really want to know what happened to it.

[jeeppapa]

Damn.
 
I kind of want to know what happened to it, but on the other hand I don't really want to know what happened to it.

Looks like they may have had to cut some people out. Cold chill just went up my spine.


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[bigmistake]

3 hours ago, jeeppapa said:

 

Looks like they may have had to cut some people out. Cold chill just went up my spine.


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For what it is worth - both of those smashed up jeeps had super clean interiors.  I had the same thought, but I'm wondering if something more bizarre happened, like a towing accident or something dropped on them while parked.

[Pete M]

some of the doors on the white one are shockingly unmolested