Jeep Creep: Off-Road Tech and Maintenance

In your Jeep Creep questions, please list your first and last names, your hometown, and your state/province/country, so that we can publish that information here. If you don’t provide this information, we may not be able to publish your question and answer. Don’t forget to be as complete as possible with the description of your Jeep and its problems, too. Send your Jeep questions to

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September 2013

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PLEASE NOTE: Due to a lapse of Federal Government funding, NHTSA is unable process safety defect complaints after close of business September 30, 2013. Consumers can continue to file complaints, but they will not be evaluated by NHTSA staff until funding and services are restored.

SoCal Seven
I live in Long Beach, California, and I have a 1985 CJ7. I have owned it for about 12 years. When I first got it everyone drove it but me (kids, friends, etc.). About four years ago, I cleaned it up for paint and put on a 4-inch Rough Country lift kit, some 33X12.50 R tires, one-piece rear axles, sway-bar disconnect, rear corner body armor, Warn bumpers and a 12,000 lb. Warn winch. About the same time, I rebuilt the T-5 tranny. Other than that, the Jeep is stock.

The inline 4.2 6 cylinder is getting pretty loose and it is time to do something with it. I have entertained the idea of a long block and keeping things stock, or installing a Chevy 350 with an automatic transmission, but I am afraid that will only cause axle problems. I’m looking for some sound advice from someone more knowledgeable than I.

I am 64 years old and have run off-road equipment (dozers, backhoes, excavators) in rough country all my life. I’ve learned how to get over things without breaking the equipment for the most part. My “hammer-down, hot-rod days” are behind me for the most part, but I still love the feel of power and you can’t beat the sound of dual exhaust from a V8.

If I go with the V8, I am looking at a ‘98 Chevy Z71 4X4 as a donor vehicle. It has a 350 with automatic transmission and I believe an NP 246 transfer case. Would it be better to use all the engine/trans/transfer case combination, or use my existing transfer case with adaptors? It is still in pretty good shape. Also playing into this is the need to change gear ratios with the 6 cylinder. Right now it is still stock and a little high geared with the 33s on it. I like using it as a trail rig and occasionally hit the dunes at Dumont or Pismo. Most of the time, I flat tow it behind the motorhome, but I do have a trailer and could trailer it. Any suggestions and advice would be greatly appreciated.
Ken Woodhall
Long Beach, CA

Ken, if you’ve had a chance to read some of the technical features I’ve written about my 1982 CJ7, you know that it has a Chevy 350 V8, TH350 automatic transmission, 4.56:1 gears, 4:1 Terra Flex low range in its Dana 300 T-case, 4-inch Skyjacker lift, Warn one-piece full-floating axle kit in the AMC 20 rear end, and 35-inch Goodyear MT/R with Kevlar tires. While I love the complete setup, living here in Arizona has two advantages over living in Long Beach. This part of Arizona has no smog tests, and we have a plethora of super trails within easy driving distance. You have to pass a bi-annual smog test in SoCal, which means if you change engines you have to get the conversion cleared by an umpire from the DMV, and you have to either tow or drive your Jeep for at least two hours before you can engage its hubs (go four wheeling).

Again, while I think the ’98 Chevy V8 and auto tranny would be an excellent choice for your ’85 Jeep—as long as you kept all the smog gear and computer with the combo—I don’t think the Seven’s wheelbase is long enough to accommodate a rear driveshaft that would live for several years. (That combination would work great in my son’s ’84 Scrambler, however, because of the Scrambler’s extended wheelbase.) In my opinion, my choice for you would be a rebuilt Chevy 4.3L V6 and a 700R4 four-speed automatic. Keep the engine’s smog equipment and its computer, which also connects to the tranny, and you should have plenty of power off-road, very good drivability on road, and pretty fair mileage as well. The shorter engine means you can use the longer transmission without compromising the rear driveshaft. And use either the Dana 300 T-case or upgrade to an Advance Adapters Atlas three-speed transfer case, which would allow you to use higher-ratio gears in the differentials.

High Idle
My 1995 Jeep Wrangler 4-cylinder is idling high, and the fuel injector is making a howling noise. I replaced a blown-out muffler, the gasket on the valve cover, the MAP sensor, the MAP vacuum line, the IAC motor, all the spark plugs and wires, and fuel injectors. And nothing seems to work. The idle is still high, the fuel injector is still howling, and I am afraid the muffler is going to blow again. Confused, please help.
Susan Duren

Susan, you need to track down what sounds like a very bad vacuum leak. One of the easier ways to do that is with a spray can of WD40. With the engine idling, carefully spray each vacuum line. When the spray is sucked in the vacuum leak, the engine’s idle will change. Since you may have more than one leak, use a piece of chalk (or something similar) to mark each leak. Run another test after you repair the leak(s) the first time. Continue until all the leaks are repaired.

Alaskan Rubi
I have a 2009 Rubicon in Alaska. I want to put a good lift on it and go to the largest tires the stock engine can push without going to 91-octane gas and a straight pipe with a power chip. I am thinking of a 4- to 6-inch Skyjacker long-arm lift and 35" tires. Could use any and all input you care to share with me. I will be going back in a long ways on trails with no one living around so I don't want to breakdown. Will be armoring the Jeep as money is available.
Dale Bell

In my opinion, Dale, a 4-inch lift, 35-inch tires, and 4.56:1 differential gears should be the best combination for you. Since you live in Alaska, ask a number of Jeepers in your area about which tire and tread pattern works best in the outback conditions you’ll be encountering.

ZJ Limited Slip
I have a ’93 ZJ with an inline 6 cylinder 4.2L engine, NP242 transfer case, Dana 30/35 differential with 3.55:1 gears and a track lock limited slip rear-end. I’m running 30x9.50 tires. My use is approximately 60/40 street vs. off-road. Is there a friendly front limited slip differential? Or a trick (leaving a spring or disc out of a factory type unit)?
Retread

Check various websites for an electric locker for your front differential, by which I mean the sites of 4-Wheel Parts, Quadratec, Summit Racing, etc.

Click on Cherokee
I have a 2007 Grand Cherokee and on hard right turns, when the wheel is all the way around, it makes a clicking sound as it goes. It's been getting steadily worse, and it's only on the right. If I turn all the way to the left, it's smooth sailing. What might be causing that, and what's the best way to fix it? Also, how long can the 3.6L go between oil changes before it starts developing problems?
Pete F. Griffin
Radford, VA

Not sure what you mean by “how long can the 3.6L go between oil changes before it starts developing problems?” If your Grand is equipped with the EVIC option (electronic vehicle information center) it will tell you when to change the oil regardless of whether your use is considered “heavy” or “light.” However, without the EVIC, I’d highly recommend an oil change between 3,000 miles and 3,500 miles in order for the engine to give you the longest possible service. As far as the wheel clicking is concerned, if the tire is not rubbing on an inner fender—perhaps it’s become dislodged from its normal location—then you have a bad wheel bearing.

Slip Yoke Eliminator
I have been searching forums high and low for an answer, and I cannot find one anywhere. I have a ‘99 TJ with a 4-inch suspension lift (the lift was on the Jeep when I bought it). My transfer case recently bit the dust for good so I ordered a new one with a slip yoke eliminator along with a new driveshaft. When I put it all in, the driveshaft barely fit in between them. I have also purchased a G2 Dana 44 rear axle assembly. My question is: with the slip yoke eliminator do I still need to use the cross member drop brackets that came with my lift kit. I know the Dana 44 pinion is longer so I might have to shorten my brand new driveshaft (not thrilled about it). I could really use direction on this issue.
Billy E. Butler III, SSgt, USAF
NAS Sigonella, Italy

First of all, Sarge, thank you for your service—I’m an Air Force veteran as well. If your driveline has a double cardan joint by the transfer case, you don't need the lowering kit unless the U-joint binds up on full droop (when the rear axle is at its lowest point). However, you also have to take care about the driveshaft being too long. It it’s too long it can cause damage to either the T-case or the rear differential. Watch carefully after each trip for leaks that might indicate seal or bearing damage. We had a project vehicle on Off-Road.com with a similar setup, and a new Tom Woods driveshaft did help put all of the geometry in line.

JK Shutoff
My 2011 two-door Rubicon won't shut the pump off when filling up. Over 21,000 miles and it just did it three times at three different gas stations. It’s still under warranty and dealer thinks it might need a new tank. I looked down the filler hose with a flashlight and see nothing in it. My Chevrolets have a little round trap door that the nozzle goes through. I'm having a hard time finding out if the Rubi's shut off is in the tank or what?
Frank Novak

Frank, if you are saying the station pump handles don’t shut off automatically when the gas flows backward in the filler hose and there’s no spring-loaded “trapdoor” restrictor in your filler tube, then you don’t need a new tank. You need the entire filler tube assembly from your cap to your tank. You need to have one installed. That’s both a safety feature and a smog-related issue and needs to be addressed.

Self-Limiting Revver
I have a ‘91 XJ with the 4.0L straight six. I use it as a mud bogger. During my last race of the season my Jeep all power at about 4,500 rpm. It didn't hit the rev limiter. It works fine while driving around, but as soon as I pin it or get the rpm up I get nothing? Do you have any idea what is wrong with it?
Harvie Hootermin

Harvie, there could be a number of things causing this, or a group of problems. Here’s a list: fuel pressure and/or volume too low, plugged fuel filter, plugged air filter, bad ignition cap and rotor, fouled spark plugs, plugged or partially plugged exhaust system (especially the catalytic converter), or a worn out motor. Take your pick, or track it (them) down.

As usual, each month, I’m shouting out a huge THANK YOU to Paul Schupp at Rock Lizard 4x4 in Kingman, Arizona, for his invaluable assistance in answering many of the Jeep Creep questions.

Previous Jeep Creep Columns
September 2013

August 2013

July 2013