RTorrez1

Did you already put those plugs in? If not, Take them back and get so Champion copper plugs. If you did put them in. How did it run? Most of the 4.0 run pretty bad with them. I put them in mine and only ran them for a couple days before I changed them out. They also tend foul pretty quick. It sounds like you are really doing everything to her. And Yes, That is a good thing since no one can really know what the PO really did to it.

odgreen

Bosch plugs are jjjjuuuunnnkkkkkkk!

straightsixjeep

Dang, I told the guy at the parts store I want the best of everything, he talked me out of champions for the bosch platinum's. He even insisted I "dont" gap them, I agreed knowing that was bs. One of them was .040 when the rest were .035. Didnt get the shocks done yet but the oil change was a great success. The pure one purolator filter along with the rotella 10w30 seem to make the xj happy. I couldnt believe that the oil pressure gauge didnt drop down super low at idle, it stayed at atleast a 1/4 way and then was steady at 40psi while driving! What are the best plugs I can put in my 4.0? Il grab some in the morning and swap them out. I think the next thing il do is change the trans (ax15 5sp) fluid, I heard 10w40 synthetic is best? I appreciate the help guys, man oh man Im in love with my new jeep. Oh and the filter it had was a chrysler/mopar filter, I guess it was just time to replace it especially since the oil was as nasty as it gets. I see in other threads that these plugs are garbage, Il get the copper champions.

odgreen

Lol parts stores are paid money to over sell them.
And yea you don't gap platinum or iridium plugs because you can damage the precious metal.
So if you did gap them you just screwed up a sucky plug. Lol
Go back and cut your losses. Buy champion plugs.

straightsixjeep

Thanks^^ And yup I guess I made one of those plugs even worse! Im sorry champions, Il never turn my back on you again. Might look into a K/N filter next, was thinking the whole cold air setup but a drop in filter would look stock and would be cheaper.

Basslicks

If you keep your stock airbox, you can increase airflow and lower intake temps by closing off the front inlet of the box and drilling a 3" hole out of the back and routing a 3" hose (or pipe) to the cowl. Lots of people on here have done it and it works great. Keeps the air inlet higher in the event of water crossings and if you do happen to get some water in, it stays in the airbox. Retains all of the stock parts as well except for the hose or pipe you added, of course.

salad

Negative, the actual best is Redline MT-90 which is an API GL-4 75W90 gear oil with synchromesh additives. The manufacturer's manual for the transmission (not a Chrysler TSB announcing that they're no longer carrying stock for 10 year old products) specifies API GL-3 75W90, but GL-4 is fine. Don't use GL-5 and don't use motor oil. Alternative products include Redline MTL, Castrol Synchromesh, and Pennzoil Synchromesh. I have some AC Delco stuff but it's a tad thin.

There may be some other stuff out there that works great but beware that long term use of an incorrect lubricant can cause serious damage. API GL-5 oil, marketed as great for towing and differential life, have new Extreme Pressure additives which destroy brass synchronizer rings in the AX-15 and other manual transmissions of the time. Synthetic GL-5s commonly have friction modifiers added in for Limited Slip Differentials which will screw up synchronizer engagement. Our old transmissions weren't designed for motor oil either, of which the primary purpose is to protect against sliding forces, not rotating gears, and control contaminants like unburnt fuel and soot. I would also recommend against Crisco lol

straightsixjeep

Thats a great idea, but is there any chance it will suck water in when its raining?

straightsixjeep

You sir have just made me smarter, thank you. Iv been weary of adding straight motor oil since it can destroy synchros, but now I know exactly why it is to not be used. Since you answered my question I will go ahead and buy Redline MT-90 tomorrow when Im at the parts store exchanging spark plugs. Wouldnt happen to know the best fluid for the front a rear diff's off the top of your head, would ya? Im thrilled to have joined this forum, were going to have this jeep in tip top running condition. My plans are to replace all fluids and worn components, drive it for a while, and maybe put a 4.5in lift and 31s on it. I didnt create a jeep build thread because if I do, it wont be for a long time. My goal for now is reliability. Thanks again guys

Basslicks

If it does, it will just remain in the airbox. I've only heard positive things from people on here using that setup.

straightsixjeep

Well then thanks for the suggestion

salad

Heh thanks, I spent several days researching that one. 4.5" on 31s sounds nice and flexy, though beware that when going up past 3" you need to start looking at things like axle shims, longer LCAs, new shackles, new track bar, dropped pitman arm, SYE, etc.

As far as diff lubes go I'm not sure. Factory open differentials are so simple I don't think it matters that much lol. I'd likely just grab a synthetic from a reputable brand and leave it at that. Mostly you want to watch out for special additives like for limited slips, and weights if you're towing. I hope someone else can chime in here.

It's a bit of a pain to make it reach this far, but to pretty much guarantee no water, run the 3" tubing/hose to the passenger side of the firewall. The cowling there is blocked, so rain must travel from the drivers side all the way over. Safeguards against snow, too, if you get that stuff. This was actually the Topic Of The Month in Advanced Tech a while back, go take a look!

Basslicks

Yup, I remember that. Forgot about that pass side configuration.

straightsixjeep

Excellent info thanks, and yes we get lots of that stuff (snow)!

straightsixjeep

Guys I need your advice on wheels. I decided I want these rims - http://www.ebay.com/itm/Cragar-Black...ht_1621wt_1163
And I found a good general grabber tire from tire rack. Now they are out of stock of my normal tire size, 225/75/15. However, they have the same tire in 235-75-15. So what do you think of these tires http://www.tirerack.com/tires/tires....omCompare1=yes mounted on those crager rims? If everything looks good Im ordering tomorrow!