What is the most important tip you'd share with MJ owners?

[Scrud]

When planning the 97 - 01 XJ upgrade, start looking for an 87 or newer 2wd comanche. They tend to be in better condition, easier to find, cheaper to purchase, and easy to convert to 4x4 with your donor XJ.

[big66440]

DO NOT second guess the dual diaphragm brake upgrade, the benefits far outweigh the cost.

[cruiser54]

AMEN to that!!!

[1989 Eliminator]

I will attest to the dual diaphragm upgrade as well!!! Braking like a corvette now

[cruiser54]

I will attest to the dual diaphragm upgrade as well!!! Braking like a corvette now

Ditch the load sensing valve correctly and you will be VERY impressed. 

[big66440]

Russell 694850 is the correct part number for stainless steel braided brake lines in our comanche's and they DO make a noticeable difference (The rubber lines I replaced had less than 2k miles on them, so they where still "new") although please note the rear line is a little too short, it seems a little stretched when the manche is jacked up all the way by the frame,,, I don't off road so I don't really mind . :MJ 1: .

[GrayWolf1691]

I have an 87 with the 2.5 renix system... I've had her for around 1.5 years so I have a little to share  :laughin:

 

1) If you have a power steering leak and you can't quite pinpoint it - check the o-ring at the pump - mine was shredded and leaked everywhere.

2) I've had fuel problems since I bought it (but hey, it was $400 with a 4 spd to swap in) - chugging out and loss of power - if it continues after replacing the fuel filter ( I've gone through 4 in the time I've had it ) and the tps and map sensor aren't the culprit - it's probably the fuel pump ( saw the ground wire post for the fuel pump so I'll see if that makes a difference though I think the pump just needs to be replaced ).

3) It's a little more expensive but switch from regular to premium gas - my mj runs much smoother and I've gained between .5 and 2 mpg ( when I'm not having fuel delivery problems ) on my commute to and from work. ( something to do with the renix system )

4) Make sure vacuum lines aren't old and cracked - replaced the one on the intake on top the throttle body and I swear I gained 15% more power and 30% better throttle response.

5) If your 2.5 is running rough try a good ground wire - I took a 1/2" thick wire and ran it from my power steering pump bolt to the passenger side of the engine bay and slapped it under one of the bolts that I assume holds the fender on - ran soooo much better.

6) DO A TUNE UP!!! I was running on 3 cylinders cuz one of my spark plug wires had come loose.

7) The 87 has ccv and if the valve cover or seals on the ccv leak it will push oil into the air filter and into the manifold burning oil which will lower gas mileage ( also builds up deposits on spark plug ) and throttle response gets worse.

8) If you have a bad vibration while driving for the love of all that is holy check your u-joints - mine at the rear axle was DUST and took 10 minutes of hammering with a sledge hammer to get out... was probably the only reason it didn't explode on me.

9) If you have a vibration up front (mine is passenger side) it might be the u-joint that is causing it. (my case)

10) If you lost your back up lights check at the transmission to see if the wires got burnt through by the exhaust.

11) Make sure your transmission mount bolts are tight! I lost a bolt, 1 was 2/3 loose, the other was about 1/3 loose.

12) If you replace the transmission mount pay attention to the way the old one came off - I put mine on backwards at first and it took me 30 minutes in the rain to realize that's why I couldn't get my fracking crossmember back on.

13) It's cheaper and easier to replace the whole hub rather than the wheel bearings or to repack them. In my particular case we broke 2 1/2" breaker bars because almost everything on my jeep is stock and has like 230k miles on it and does not like to come apart... ended up just pulling off the whole assembly. So... 13.5 would be PB Blaster! lol

14) When replacing serpentine belt, make sure you tighten the damn bolts... I forgot and trashed a belt and luckily didn't overheat my engine.

15) When replacing the alternator make sure everything on it is tight... I had one come apart on me.

16) If you end up with an oversize battery - strap that sucker down tight! I cut a hole in mine while offroading and the battery acid trashed my alternator... which led to #15  :rotf:

17) Always keep a chain in your MJ, you never know when you'll need to pull someone out of whatever they got themselves into

18) Always keep jumper cables in your MJ, cuz you never know when you'll need to jump someone... or need a jump yourself  :laughin:

[projectMANCHI]

If your alternator is not charging your battery, check your instrument cluster fuse. I learned this the hard way after replacing my alternator and battery twice. Supposedly if your battery/charge light isn't functioning your alternator won't either.

[big66440]

If you replace your speedometer cable make sure you route it away from the EGR tube going from the exhaust manifold to the intake manifold (4.0 engines not sure about the 2.5) to keep it from burning and having to buy another one.

[big66440]

If you have a "knocking" noise from your rear end while turning and hard straight line acceleration and have a Dana 35 pop the differential cover and inspect the spider gears even if you do not go off roading these are weak links on this differential and are not difficult at all to replace along with the axle shaft bearings ( the bearings closest to your rear wheels).

[big66440]

If you need the part number for the inner seal for the bolt in axles on DANA 35's (not sure if c clips are the same ) its SKF 13671, no major auto parts store can look it up for some reason.

[MancheKid86]

You can never have too many spare parts

[BlackBeast]

X2

[Mirfster]

Hello all, new member here.  There is tons of great info here and I am glad I found this site.  Learning a lot so far and will be making sure to get some of the great advice from this site.  :thumbsup:

 

While I am not a MJ Owner (yet), still shopping for one; here is what I have learned so far:

 

Always get the VIN and check it (there are a couple great links in these forums for checking VINs).  In my searching, I have tried to buy a couple MJs (3 so far), but have seen a lot of sellers who do not want to provide the VIN.

 

For me that is a red flag, especially on the ones that are listed as Eliminators.  Last thing you want to happen is to get your dream truck, find out it is not what you though and then have to face a "Possession" charge.

[cruiser54]

https://docs.google.com/file/d/0Bz4d205LaED2SUxMOGZnY3RjaEE/edit?pli=1

[big66440]

Do not remove your thermostat or swap out the thermostat for a cooler temp unit ( normal opening temp for 4.0's is 195 degrees) your gas mileage and performance will decrease.

[Manche-89]

Oh I would have to say, the biggest tip would have to be spray the cap crappy out of any bolts you wanna take off, shackle bolts especially, weather it's pb blaster or jb 80, whatever you like to use, it'll save you a ton of time.

[Jackrabbit41]

If your 4.0 is idling high or your constantly blipping the throttle to try and get it back down, try changing out your old single port fuel injectors for the 4 port high flow injectors, engine will idle very smooth plus increase in power and better fuel mileage I think this was one of the best mods I did.

 

Where can I get some of those? That's happens to me all the time.

[cruiser54]

 

If your 4.0 is idling high or your constantly blipping the throttle to try and get it back down, try changing out your old single port fuel injectors for the 4 port high flow injectors, engine will idle very smooth plus increase in power and better fuel mileage I think this was one of the best mods I did.

 

Where can I get some of those? That's happens to me all the time.

 

That isn't the ONLY reason that you can get that symptom.

 

That said, contact Programbo on Cherokee forum for a refurbished set of 746 injectors.

 

Of my Tips, how many have you completed?

[tjheems]

A few lessons from my travels with Jenny (89 MJ)

 

1.) Go learn how to weld.

 

2.) Keep an excel spreadsheet with all the different years of your major components. As you inevitably start swapping, modding, or otherwise "improving" your MJ, you will begin to cross years with later XJs, early XJs, different year MJs, all sorts of crazy stuff.

 

The proof is in my story. Complete 4wd swap, AX-15 from a 97 XJ, long arm BDS-kit installed - life is about to be awesome. Everything is tight, installed, pilot bearing saga over came, "crank crank crank crank - oh crap." Checked every single electrical part involved in sparking...timing, TDCing, CPS replacement about 3 times, distributor, plugs, wires, multi-metering the heck out of everything I could think of, still no spark. Oh wait - whats that? You swapped out your old 2wd transmission for a 1997 4wd model and replaced the clutch? But you ordered the pressure plate for a 97 and not for the 89 because you are an idiot and thought you'd stay true to the transmission year? And then you wasted so much time diagnosing it that you couldn't get the part swapped out, tranny stabbed, and everything all buttoned up prior to your deployment so you've had 7+ months of sitting and thinking quietly about what a bozo you are for such a simple and costly mistake? Man that sucks - my life.

 

3.) Obligatory floor pan rust plug* - It's like Newton's 4th law of Motion "Your MJ floor is rusted" - Sir Isaac Newton

 

4.) 4wd conversion is easy - just do your research and pay special attention to things like the pilot bearings being the proper interior and exterior diameter for your applications.

 

5.) invest in the Novak cable shifter for you T-case - it is epic.

 

6.) consult Comancheclub forums first and then Cherokeeforum - you aren't the first person to have the problem...you just may be really bad at using the search forum feature.

 

7.) If it is worth doing. It is worth doing right.

[CommanderGambit]

If you are having taillight troubles, then check and most likely rework the ground connection inside the drivers side taillight pocket.

 

If you the fuel gauge doesn't work and the fuel pump is having trouble, check the chassis ground back at the tank. I have had to re-ground this on 3 different MJs' so far... :headpop: I just go to the frame rail, or bed, depending on which is closer to the break in the wire.

this is definitley something i need on fuel pump previous owner put another gauge in and both read full bit never go down thanks for this, a shop said i needed to buy the whole unit again

[Money_Pits]

When working underneath on a real rusty/dirty mj, wear safety glasses, preferably ones that seal around your eyes. Lost 45 minutes and almost an eye last Sunday trying to get those damn u-joint bolts off to drop the driveshaft when a hunk of rust slipped between my glasses and eye.

 

Invest in a company that makes automotive cleaning/lubricating/penetrating solutions, it'll help you feel better about the amount of money your spending on that stuff.

[Jackrabbit41]

A bad oil filter adapter gasket ring can be misdiagnosed as a bad rear main seal :doh:

(i cleaned the hell out of my engine before searching for the leak) quick and cheap fix :banana:

I just did an ax15 swap and put a new rear main seal. Its already leaking (so it thought), but it could be the gasket ring? I've never heard of that. 

[Pete M]

clean the area and see if oil is leaking out.  the oil filter housing adapter thingie has a set of little o-rings that can leak with age. 

 

on the other hand, it took 5 tries to get my RMS to stop leaking, so anything is possible.  they invented a double-lipped RMS to deal with cranks that have worn little grooves where the regular RMS lip sits.

[Minuit]

Small one, but one worth thinking about:

 

Almost all MJs are actually getting 4-10%, possibly more, better gas mileage than you think they are. They're also going about 4-10%, possibly more, faster than the speedometer says. Reason? The factory tires on these trucks ranged from 195/75/15 to 225/75/15 but almost every single truck on the road today has bigger tires than that on it now. Without adjusting the speedometer to match (which almost nobody actually does) this throws the speedometer off by a certain percentage. The fix is to replace the speedometer gear, which takes maybe 20 minutes. The gears themselves can be usually found online for ~$20 used or $40 new. See this chart for the correct speedometer gear for your application: