3 problems.....

My friend asked for help with his 90 auto 4.0 tomorrow and has 3 main problems. small lift with 31's and little things
1) squeaky belt. i tried tightening, spraying stuff, previous owner did water pump and belt but it is still load all the time. i can't tell where its coming from next i was going to pull the belt off and spin everything but anything i should look for? fan clutch?

2) He also said the truck won't start when you turn the key sometimes he said it just makes a tick. I am going to check the wires to the starter and battery but i think i recall seeing a new starter. other than checking that stuff anything else in the ignition?

3)My buddy says he is getting about 100 miles to a tank. sounds bad but not sure why its that bad. there is like no exhaust on the truck. i think its just cat but should that make the mpg that bad?

I gotta look at the truck tomorrow so any guidance would be helpful thanks

1. Get a new belt... Edit: didn't see previous owner did the belt. Know how old it is?

2. Battery could be going bad. Or bad connections, just do some battery cable upgrades while you're at it

3. Could be a number of things. When was last tune up? Could be O2 sensors...

2o this as every Renix era Jeep needs it done at least once in it's lifetime.




Renix Ground Refreshing
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.
　
　
If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.
　
Revised 11-28-2011

oh ya its a renix huh. never had one but heard things. that sounds like it could fix allot.
as for the belt its no more than a year and never fixed the squeak what else could it be? i don't know when the last tune up was done but aside from that and the o2 any thing to check or can i even check the o2 sensor

Would the no start be part of a NSS? Or do Renix Jeeps not have that?

My squeeky belt ended up being the idler bearing. Cheap fix.

kenny schmitt said:

oh ya its a renix huh. never had one but heard things. that sounds like it could fix allot.
as for the belt its no more than a year and never fixed the squeak what else could it be? i don't know when the last tune up was done but aside from that and the o2 any thing to check or can i even check the o2 sensor

Click to expand...

Put new plugs (Champion Coppers), wires, cap and rotor-the ones with brass, not aluminum terminals. Do the ground refreshing. Inspect all the hoses/piping for vacuum leaks. Make sure the intake manifold to head nuts and bolts are snug. Clean the throttle body and IAC.

All of the above is preventative maintenance and you want to KNOW it's been done before getting off on any other tangents just yet.

Dirt Yota said:

Would the no start be part of a NSS? Or do Renix Jeeps not have that?

My squeeky belt ended up being the idler bearing. Cheap fix.

Click to expand...

Renix jeeps have the same NSS as later ones, but there's no click for a NSS failure.

As for the belt squeak, make sure the tension is right. It's rare to get enough tension doing it by feel, and the correct tension is surprisingly high.

i cleaned the grounds and starter and power cables and now the truck starts every time. but that belt is still load i took it off and all the pullies feel fine how do i know which one to change?

I had a new belt squeal just by the 'quality' of the belt, maybe the rubber compounds used? dk. But went and just bought a Gator belt just shooting in the dark to try and get rid of the damn squeal and installed. Not a sound for three years now. Just my .02

Squeak or squeal is usually a bad water pump bearing, or idler pulley bearing or AC clutch bearing, or alternator bearing. Also check the rubber in the harmonic balancer on the crank shaft for bad cracked, loose rubber.


For O2 sensor testing:

http://www.naxja.org/forum/showthread.php?t=1012701&highlight=oxygen+sensor+testing