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June 2013 Your Jeep - Tech Questions

Posted in How To on June 1, 2013
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Photographers: Jp Archives

Stroker vs. Chevy V-8
I have a ’93 Wrangler that has around 300,000 miles on it (its speedometer quit working around 50,000 miles). She was my daily driver for years, the engine still runs, but let’s just say the old girl used to run a lot better. Anyway, I’ve decided to rebuild her, and after reading lots of articles about stroking a 4.0L, that’s what I decided to do, but all of my friends are saying drop a Chevy V-8 in her. They claim it’ll be cheaper, easier, and more powerful. I’m not sure. I was wondering if you guys at Jp have ever written an article comparing the two options, what works better what doesn’t, the good the bad of both. The cost involved in both. I’d be very interested in reading about the comparison.
Jacksonville, FL

This is a tough, but good question. I am not sure that we have an article like this, but it is a good idea. Until we do, let’s talk about the two options and hopefully it will help you make your decision. There ain’t much to complain about a simple old 5.7L GM swap. Hundreds have been done to all manner of Jeeps and the results are almost always beneficial. But I’d say a V-8 swap when done properly rarely if ever means you are only swapping the engine. Maybe if you already have a stout auto tranny, a T-18, or even a NV3550 or AX15, but many Jeep transmissions are just not up to the task of handling V-8 power. So if you factor in the cost of having to upgrade transmissions to accommodate a V-8 swap that may push the cost of an engine swap up over the cost of building a stroker. Having said that, many Jeep owners have upgraded to beefier transmission in a Jeep without swapping engines, so if this is something you would consider anyway, then the cost of a V-8 swap may be the path of least resistance.

A stroker is nice because you don’t have to modify the wiring harness, you don’t need any adapters, basically all your accessories already work, and the engineers at Jeep did all the grunt work of getting things packaged. All the cost comes from machine work and tuning the engine to run well with its new larger displacement. Another question is which engine will end up being more reliable? There are countless Chevy 350s and 4.0Ls with 350,000 miles on them. Both are reliable, but a heavily built stroker is probably never gonna be as reliable as a stock Chevy 350. So far, Pete has had pretty good luck with his stroker, but for whatever reason Christian’s stroker liked to eat valvetrain components and he eventually went back to the stock 4.0L in that Jeep. We know plenty of Jeepers out there with high mileage junkyard Chevy mills still puttering down the road or trail.

Surrender Is Its Only Tactic
The problem is that I have an ’89 YJ with the never-dependable Peugeot transmission with 144,000 miles on it. I am trying to find out my options for a swap. I’m looking for the most economical swap and something I can do in a weekend because the Jeep is my daily driver. Any suggestions would be greatly appreciated.

Yea, that’s a familiar problem. The ’88 YJ I just bought also has a dead BA10/5 between the framerails. My plans are to swap it out for an auto tranny, but that’s not necessarily the easiest thing to do. If I were you, and you are okay with keeping the Jeep a manual, I would look to swap the Peugeot for an AX15 from a later YJ. You’ll need the transmission, a bellhousing from a ’95-or-newer YJ or XJ with its clutch fork and input bearing retainer, a clutch slave cylinder/clutch master cylinder/hose kit (Quadratec PN: 52104113), a 23-spline NP231 input gear (yours is most likely 21-spilne behind the BA5/10) a throwout bearing, pilot bearing, clutch, pressure plate, and both the transmission mount plate and NP231 shifter from a YJ originally equipped with an AX15. With this setup you get away from the internal-hydraulic throwout bearing of the Pugeot and ’94-earlier AX15 and should be able to use your existing driveshafts with a much better transmission. Wanna know how to swap the Peugeot out for an auto tranny? Well, you’ll have to keep your eyes peeled on upcoming issues of Jp where I’ll be tackling this swap.

That’s Offsetting
I have a ’98 TJ with 16-inch wheels from a Cherokee with 11⁄2-inch-thick wheel spacers to run 305/70R16 mud terrains. I would like to get rid of the wheel spacers and wonder if I could run the 305/70R16s on Rubicon wheels. Would this combo work or would I still need wheel spacers? I’m trying to get rid of the spacers because I have heard they are hard on axles. I really like the look of the Rubicon wheels, but will probably have to buy something aftermarket with the correct backspacing. With 305/70R16 I was told that I would need 3.75 inches of backspacing.

We also love the look of the factory star Moab wheels, but I am not sure it’s the best option for a Jeep that sees much trail use. Rubicon wheels sit in pretty deep with about 5 inches of backspacing. Our pal is running some 315/75R16 Goodyear MTRs on his TJ Rubicon with Moabs and 1.25-inch spacers. He has complained that the valve stems on these wheels have an uncanny ability to get damaged while out on the trail. He is currently making the swap to different wheels.

Wheel spacers when built correctly, installed correctly, and maintained correctly are fine and should not be any harder on your axles than large, wide, heavy tires on a wheel with less backspacing are. Now having said that wheel spacers do mean more possible points of failure, and there are lots of cheap wheel spacers out there. The fact is some aren’t what they claim. Use red Loctite on the inner lug nuts, and all should be checked for proper torque every other oil change or so. Also if you get one of the studs to spin in the adapter it’s a huge nightmare to just remove a wheel. I’d recommend getting some wheels you like the looks of with not quite as much backspacing as these factory wheels. Look for ones with 3.5 to 3.75 inches of backspacing. If you are married to the Moabs, use only quality wheel spacers such as those made by Spidertrax.

More Bench Racin’
If you had a ’98 Jeep Grand Cherokee Laredo with a 5.2L V-8 and auto tranny with Moab nearby, where would you spend $10K to fix it up? Yep, that’s what I’ve got and those are my parameters. So, if you were me, how would you do it?
Name withheld
Via email

That sounds like fun. We love figuring out how to spend other people’s money. Honestly, though, it sounds like you have a good base for a buildup in the ZJ with a 5.2L. First I’d start by looking into a set of Unitbody/chassis stiffeners and rocker guards. These parts will help ensure a long wheeling life for your ZJ. We found a set of T&T Customs “Uni-Body Stiffeners” for about $130. Factor in $300-$500 for some rocker guards. Add in $1,500-$2,000 for a front bumper like one from TrailReady and a reliable yet inexpensive 8,000lb winch. Add in $600-$2,000 for a 4.5-inch suspension system like one from Rubicon Express. Look to spend $400-$1,000 for a Dana 44 rear axle out of a late ’80s Jeep Cherokee XJ or ’97-’06 TJ (both of which will require some new bracketry). Lockers front and rear will set you back $1,200-$2,000. Add $1,000-$1,500 for some 4.56 gears and gear setup. Figure that 33-inch tires and some steel wheels will set you back $1,300-$2,000. Another $800 for tabs, brackets, bumpstop-lowering, and miscellaneous installation costs and you are probably looking at just over $10,000-$12,000. But you’ll have a capable, comfortable Jeep that you can drive to Moab or anywhere. If you can find parts used and/or do installation of various parts yourself, you can save more cash and save up for more lift, bigger tires, a rear bumper with a swing-out tire carrier, or maybe a rollcage.

Six-speed Jumping Out of Gear
I own an ’08 Jeep Wrangler. Once in a while when trying to start off in First gear the transmission pops out of gear. Is that normal on this Jeep, or is something wrong?
Bluffton, IN

Ready for some bad news? There is something terminally wrong with your transmission. Unfortunately, it will need to be rebuilt. Our ’07 JK project vehicle with about 89,000 hard miles does the same thing. You can hold the shifter in First gear when starting from a stop until you can get the transmission rebuilt or replaced. Unfortunately, the problem won’t go away without some costly mechanical surgery or replacement. Some Jeep owners have had their dealership repair their transmission under the lifetime powertrain warranty, but I would not count on it, especially if you are not the Jeep’s original owner or if the Jeep is modified.

Unfortunately, the NSG370 six-speed transmission found in later TJs and JKs just isn’t as durable as the good ol’ AX15, or even the NV3550 five-speeds.

TJ vs. XJ
I’ve got an ’06 Wrangler SE with the 2.4L four-cylinder, six-speed, and 3.73 combo. It’s got a 21⁄2-inch Rough Country lift and 31-inch tires. It’s what I drive to work mostly and do not do a lot of off-roading except for fishing adventures and general sightseeing. It gets about 18 mpg on average and has gotten 22 mpg on long road trips. It runs pretty good around town and on the back roads, but it’s completely overwhelmed on the highway or interstate if speeds are much over 55 mph. I do live in a very hilly area in Kentucky. Would having lower gears installed give me the ability to maintain my speed on the interstate? Currently Sixth gear is for downhill use only.

Next question involves swapping engine and transmission to a 4.0L HO and auto out of an ’00-’01 XJ. I’ve seen a few XJs lately on Craigslist that have been rolled, but the drivetrain is still good. I know this can be very time-consuming, but just curious about computer out of an XJ working on my TJ. I’m aware of all the mechanical things that would be different between the two, but motor and tranny are the key components I would need. And I realize it’s not an easy exchange, but would like some input.

I’ve owned four XJs (a ’96, two ’00s, and an ’01), but this is my first Wrangler. When my kid was small I always thought Wranglers were the most useless vehicle on the road, especially compared to XJs, but when he got older and I didn’t need the extra doors, my opinion changed.

I thought I’d give a TJ a try when I found a repo at the bank that I couldn’t pass up. I was correct about the kinda useless part, but they sure are a lot more fun to drive and wheel than an XJ is. I’m getting too old for shifting all the way to work—17 miles and 18 traffic lights one way—and would give a few more dollars at the gas station to not have to worry about merging with traffic or getting passed on the highway by semis.

One last note, I thought the Jeep wave was a pretty funny subject. In the 12-plus years that I’ve driven XJs that were all lifted and tricked-out, nobody ever waved at me. But as soon as you own a Wrangler, everybody waves, even when it’s basically stock.
Gary N. Owens Jr.
Catlettsburg, KY

Well, Gary, we here at Jp love us some four-cylinder Wranglers for sure. And we love Cherokees, too. We’ve all owned an XJ in the past. Right now Pete and Christian each have a four-banger YJ Wrangler, and I am in a pretty serious relationship with a beater ’97 TJ Wrangler. None of us owns a later TJ with the 2.4L, but honestly, I’m sure I will own one someday. The trick seems to be to keep these Jeeps light and keep the tires small. Yeah, gearing the axles is a must in order to keep the little engines in their power band at highway speeds when bigger tires are added. Using my handy-dandy Jp app on my iPhone, I can see that your Jeep should have at least 4.30 gears with its new 31-inch tires. Personally, I’d look into some 4.56 gears for your Dana 30 front and Dana 35 rear axles. Once geared, I bet your little Jeep will be screaming down the asphalt once again.

Swapping in an engine and transmission from a XJ is gonna cost way more than trading your Wrangler in on one with a six-cylinder and an automatic would. Also, a swap like that would be in a legally grey area since your TJ will be newer than the donor XJ. Most swap laws stipulate you use an engine of the same vehicle year or newer when swapping. You can sell me your four-cylinder TJ (I’ll take that special deal you might offer since I look like your brother). Your money will be better spent on a Jeep that already has a six-cylinder and an auto, and you can let the factory do all the manual labor. Plus, then you can look for a TJ with a Dana 44 rear axle, a hard top if you want one, and or any number of other options your current TJ might not have.

Regarding the Jeep wave, having driven many Jeeps I think most of the modified XJ crowd is hip to some extent. While driving our Jp JKs, when I wave I get weirder looks from other JK owners. They all seem to have no idea why I am waving. Oh well, I still wave to pretty much any Jeep regardless of what Jeep I’m driving.

More JK Issues
Many thanks to you and the Jp staff for a great magazine! Two years ago I bought an ’07 JK Rubicon Unlimited with 24,000 on the clock and an automatic transmission. It was originally sold in New York. At 40,000 it began using oil at a rate of one quart per 1,000 miles. Two treatments of injecting a third of a can at a time of Sea Foam through the brake vacuum hose completely eliminated all oil usage. I now use Sea Foam with every oil change and have zero oil consumption at 55,000, even on long trips.

Around the same time I performed the first Sea Foam service, I also noticed the Jeep had become reluctant to shift into First. It’s an auto with the 4.10 gears, so this seemed normal on flat ground under light loads. However, it raised red flags when towing up steep hills from a stop. The Jeep didn’t even shift into First when I pulled the shifter down to the lowest setting...until my wife filled up with high 92-octane fuel. I immediately started looking for signs of an aftermarket tune and eventually found a Chrysler “Authorized Modification” tag which appears to indicate an ECM reflash. Can you shed any light on this modification? Would this flash prevent the Jeep from downshifting and revving when fed low-octane fuels? Does power output directly affect transmission performance?
Elkview, WV

Glad to hear the Sea Foam treatment worked for you. It seemed to improve the oil consumption issues that our ’07 JK had, but it is still using some oil for sure. As far as your transmission problems, that does sound odd and I don’t see how the transmissions shifting could vary with the octane of the fuel you are running. I talked to a few friends about your issue and they said that the factory would perform ECM reflashes to take care of weird quirks with the electrical system. No one I talked to thought the computer reflash and transmission issue were connected. I would take the Jeep to a trusted dealership and or transmission shop and see what they think about why the transmission is not downshifting. It could be a simple fix like a gunked up solenoid.

More JK Oil Burning
I have an ’07 JK Sahara, and like many others, mine is plagued with several of the issues that seem to be common to other JKs, such as oil burning and rear main seal leaking. The letter from B. Dutkiewicz in the March ’13 issue seemed to pose all the questions I have. Among other things, my JK consumes oil, and now at 54,000 miles it has developed a rear main-seal leak. I like the JK and don’t want to get rid of it. I’m seriously considering putting in a newer engine, but if the newer ones still have the oil problem, that would seem to be pointless. Do the ’09-or-newer engines also have the oil problem? I’ve found a ’11 engine for $1,100, and it’s supposed to have 18,000 miles on it. Does Larie at Jeeps R Us rebuild the engines to correct the problem, or does he just rebuild the engines back to original factory specs? Between rebuilding the engine or buying a newer engine, what would be the best solution to the problem? Has Jeep corrected this problem in the newer models, or what the heck are the folks at Jeep thinking?
Dave Bavier
Lake Havasu City, Az

Dave, sorry to hear that this problem is affecting you, too. It looks like the cheapest solution to the oil consumption might be the Sea Foam treatment. As far as we know, the issue with the bearings that don’t have a method of indexing into the rods is still a problem for at least the ’07 and ’08 JKs, so as you suggest, a rebuild is just a temporary fix. Since writing about Mr. Dutkiewicz’s problems, we have heard rumors that somehow piston rings were installed incorrectly in some 3.8Ls from the factory, with the rings stacked upside-down or with the gaps lined up. We can neither confirm nor refute this, but it could be an added cause and/or related to any excessive oil consumption. As far as the rear main leaking, that is probably only cured with a new, properly installed seal. It may or may not be related to overheating caused by the bearing spinning, which would end in a terminal bearing knock. A friend who is a full-time mechanic always recommends replacing an engine with a factory-built, low-mileage unit like the one you have found. His thoughts and experiences are that the factory will do a better job of building an engine and use higher quality parts than most commercial engine rebuilders. Also, as said before, for whatever reason the later 3.8Ls seem to have less of an oil-consumption issue. This could be because the factory rectified the issue, or because fewer of these newer JKs have enough mileage on their clocks to develop the problem. One thing is for sure, these things run hot and any carbon buildup on the piston rings, valves, or combustion chambers seems to make the oil consumption issue worse. Once the engine starts using oil, many owners don’t notice the low level—then the engine is operated at low oil levels, which exacerbates the connecting rod issue and leads to other engine failures such as cam bearing and tappet damage. I’d recommend trying the ’11 engine and keeping on top of a Sea Foam or other top-end carbon cleaning system with every or every other oil change.

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