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September 2012 Your Jeep Tech Questions

Posted in How To on September 1, 2012
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What’s What in Jeep Nut Land?
Greetings and thanks for taking time to read my email. In a nutshell I’m new to the Jeep world and I’m about to buy a Jeep. Can you tell me the difference between the JK, TJ, LJ, YJ, CJ models? Forgive my ignorance, but a Jeep is a Jeep for all I know; I would like to know the basics before I buy one so I can buy one that suits me. Thanks again for taking time to help a newbie.
Curtis Findley
Lago Vista, TX

Curtis, Oh boy! That’s a good and totally reasonable question…with a long-winded answer. Welcome to a new obsession—you are about to learn more about Jeeps than many people will ever want to know. The first were built for the military during WWII. They are small and are now getting rarer. There are several military versions of Jeeps. The earliest “production” jeeps were non-standardized designs known as the Bantam BRC-40, the Willys MA, and the Ford GP. These are all exceptionally rare and highly valuable. You’re not likely to find one on craigslist.com. Shortly thereafter, production specifications were standardized and the rest of WWII saw the Ford GPW and Willys MB, with Bantam relegated to making only the trailers towed behind the military jeeps. Once WWII was over, Willys built civilian Jeeps which were first marketed as a tractor that you could drive to town. This CJ-2 (known as the Agrijeep) was the beginning of the CJ. The ’46-’49 CJ-2A, ’49-’53 CJ-3A, and ’53-’64 CJ-3B are basically civilian versions of the early military jeeps with some variations. Then came the ’46-’65 Willys Wagon, ’47-’65 Willys Truck, and two-wheel-drive ’48-’50 VJ Jeepster. During this time military versions of the flatfender, including the ’50 CJ-V35/U, ’50-’52 M-38, ’52-’57 M-38A1, and ’53-’57 M-170, were built. The civilian CJ-5 (which was the longest-running production civilian Jeep built) was made from 1955-1983 and had several mechanical and aesthetic variations during that time. Next came the CJ-6; it was a longer version of the CJ-5 built from 1955-1976. During this time Jeep also sold fullsize Jeeps known as FSJs. This group includes the ’63-’91 SJ Wagoneer and ’74-’83 Cherokee, and ’63-’88 J-Series trucks, of which military versions called the M-715 (truck) and M-725 (ambulance) or M-726 (telephone maintenance truck), M-724 (welder truck) were built from 1967-1969. Next was the ’67-’86 CJ-7, which was a little longer than the CJ-5s and has a larger front door opening. The ’81-’86 CJ-8, or Scrambler, was a longer version of the CJ-7. Somewhere in there the ’84-’01 XJ Cherokee was built. This is the smallish squared off hard toped, four- or two-door, grocery-getter that you probably rode in as many Americans did. The XJ was extremely popular, sold millions, and continues to be a great rig for trail or road. There is a pickup version of the Cherokee known as the MJ Comanche built for the 1986-1992 model years. To get back to the open top “Jeep” Jeeps, next we have the ’87-’95 YJ Wrangler, which was a modernized version of the CJ-7 with square headlights and a more “fancy” dash. During the Wrangler’s run the ’93-’98 Grand Cherokee, or ZJ, was built. The next open-top Wrangler was the TJ, which was again an evolution of the CJ-7 and YJ. The ’97-’06 TJ featured full coil and link suspension. There is a longer version of the TJ commonly known as the LJ or TJ Unlimited. There was also a newer ’99-’04 Grand Cherokee version called the WJ, followed by the ’05-’10 WK, and lastly the ’11-present WK2. The most modern open-top Jeeps are the ’07-present JK Wranglers, which come in two- and four-door flavors. Oh poop—we forgot the KJ Liberty, all the DJs, the C-101 and C-104 Commando, the CJ-10, FC-150, and FC170. What else did I forget? Other foreign-sold versions of the above and Jeeps built in other countries. Did we mention that practically all of these Jeeps have sub-models like the Sport, Rubicon, Laredo, Tuxedo Park, Renegade, and so on?

GM Parts in a Jeep?
I have an ’80 CJ-7 and I am currently trying to rebuild the steering column. It’s nothing too crazy, but I’m having a hard time finding the upper bearing. Lots of people have said to use any GM Saginaw bearing, but I wasn’t sure if that is correct. Any clue about who sells the correct part for a CJ-7?
Ryan Kennedy
Glendale, AZ

Do you have a tilt column? Is it loose and sloppy feeling? If so, the bearing is probably fine and you just need to disassemble it to get to the four bolts that hold the tilt tight. They almost always back off and loosen in the ’70s-‘80s GM steering columns. That said, yes—the Jeep bearing from that era should be the same as the GM. If you’re not a cheapskate, Ididit (ididitinc.com) has a drop-in replacement column for your vehicle, but they’re not cheap. They’re good, but not cheap. If you want just the bearing, the Crown Automotive (crownautomotive.net) part number for the upper bearing is PN J8127850.

JK Diesel Power
I own an ’08 Rubicon and I would be interested in getting a diesel installed. Do you have a list of companies that can do the conversions?
G. Newell
Via email

Ha, when we were at Moab Easter Jeep Safari 2012 we must have heard five different companies that claimed that they were the first to get a 4BT running in a JK. We don’t know who was first, and honestly we don’t care. Don’t get us wrong, we’d love it if Jeep sold a Diesel Wrangler in the U.S., but in our opinion the costs of a swap don’t match the benefits it would yield. Not that we’d jump at the chance to pay for a Hemi conversion, either. Having said all that there are a couple of options if you just have to have an oil burner in your JK; Jeff’s Jeepyard or Bruiser Conversions (jeepyard.com), Burnsville Offroad (burnsvilleoffroad.com), Jeff Daniel’s Jeep Customizing(jeffdanielsjeeps.com). These are just a few that we have heard of.

One-Way Winch
The other day my winch quit working—sort of. It would spool out, but not in. What happened?
Josh
Banner Elk, NC

Josh, it sounds like you have a solenoid that went bad. That can happen if you overload a winch or sometimes they just go bad with time and weather. We recently had this happen on one of our winches and we learned a cool trick from a buddy that may just help you or someone else get off the trail. This trick worked on an older Warn winch with a bad solenoid that was causing the winch to spool out but not in. Basically we just swapped these two leads on the winch motor (pictured). That allowed the winch to turn spool in, but not out. Once we were back at home we diagnosed which solenoid was bad and replaced it.

Carburetion for Tha’ Nation
I recently bought an ’83 CJ-7 with a 258 six-cylinder. Upon closer inspection I noticed that the previous owner had installed a Weber carburetor and tried using the original air cleaner housing. Well, needless to say it did not fit, so they made it fit by cutting and riveting to make it work—kind of. I bought the May issue of your magazine and read the article about the guy who has the ’85 CJ-7. You recommended a Weber or a Motorcraft 2100 carburetor. Isn’t the 2100 for the V-8? I guess there must be an adapter to fit on a two-barrel manifold. The Weber you mentioned is that the one you can get through the Quadratec? I plan on using the Jeep most of the time in the mountains on the weekends. I want something reliable. Is it true that Webers need a pressure regulator? And I’ve also heard that Webers are harder to tune. Is that true? There are also two pipes attached to the bottom of the existing air cleaner housing that run to the exhaust pipe. I would have to disable them to use the new air filter housing.
Al Finch
Montana

Al, Yep, the Motorcraft 2100 is sometimes used on Ford I-6, V-6 or V-8s or AMC V-8s. Many of these engines have a similar displacement to the 258 six-cylinder in your Jeep. The Ford 260, 289, or 302 V-8s, or the AMC 304 V-8s come with a Motorcraft 2100 ideal for our Jeep engines. These carbs are well known for running smoothly off-road. You would want to look for one stamped 1.08 on the side (indicating the venturi size). Most info we have seen suggests recommend running #47 jets on a 258. Any used carb will probably need a rebuild and the power valve is known to blow out on the 2100s. Also you will need an adapter plate for your one- or two-barrel intake. Now having said all that, your Weber, with the correct air filter housing, can also be a great off-road carb. We found a Weber replacement air cleaner assembly, PN 51312.82 on quadratec.com for under $20. We also noticed installation instructions for the Weber kit on its website. The instructions should tell you how to tune your carb and what to do with all the vacuum hoses and any exhaust ports that formerly went to the Carter. They also address the fuel pressure regulator in the instructions by saying it is only required if your fuel pressure is over 3.5 psi. As for the exhaust ports, if you don’t have to worry about emissions testing, just close off the fittings that go to the exhaust. If you want to keep the emissions system, just use tees to run all the vacuum lines to the Weber and run small filters (like a crank case filter or valve cover breather) to the hoses that are supposed to connect the factory air cleaner.

One of our friends is running a Weber on a 2.5L four-banger in his CJ-7. Webers are apparently sensitive to the idle screw setting so if the idle screw is too far in it will never run right. Follow the idle setting instructions carefully. Also make sure the vacuum advance is hooked to the correct ported vacuum fitting on the Weber and not to the manifold vacuum fitting right next to the ported vacuum. Lastly, if you have tuned everything correctly but the Jeep still runs funny, you may need to bypass the wiring from the Carter’s computer to the distributor and connect the ignition module directly to the distributor like an earlier CJ. The Carter’s computer may be messing with the distributor because it can no longer find the carb. Also, our pal noticed that the engine tended to stumble a bit on inclines, but ran smoothly on declines. A little research showed that others had noticed this with the Weber and were actually running their Webers backwards relative to the direction the instructions dictated. Since turning his carb 180 degrees (pictured), the Jeep runs much better on inclines. It stumbles on declines, but that’s less important since you can use the clutch to keep the engine running or let the damn thing stall and coast downhill.

Cold Mud Intake Kit
I have an ’01 Jeep Grand Cherokee and it has the 4.0L engine in it. I was wondering if I were to put a cold-air intake kit on it if I would still be able to go mudding? I don’t do hardcore mudslinging, but just the occasional light mudding when it rains.
Weston Decker
Weatherford, TX

Weston, yours is a good question because generally speaking a cold air intake kit is not going to be as resistant to sucking up water or mud while “mudslangin’” off-road because they usually do away with the airbox and run an open-element air filter. The factory airbox will deflect more mud and water than any open element. You can make a deflector that protects the open filter from any direct splashes in the engine compartment, but if you really submarine your WJ no deflector, airbox, or open-air filter is gonna prevent water from entering your intake and probably your engine. It’s up to you to know what’s happening with your rig. If you think you may have dunked the Jeep deep enough to inhale some mud or water, immediately shut off your engine and check the filter and intake. If there is water in the air box, throttle body, or intake, you need to clear your engine of any water. Do this by pulling the plugs and using the starter to turn the engine over until all the water has been blown out. You could also run a snorkel if you are into that look and it won’t get ripped off on a tree or other brush.

L-head Idle Issue
So I rescued this ’46 CJ-2A from the scrap pile. Plugs were broken off in the head, and on and on as these things go. Engine has been reassembled with a Toyota starter (thanks Jp!) and it will start with just a bump on the floor button. The issue I’m having is that it will not idle without choke. There is a sweet spot where it gets really smooth, but the idle is high and 1⁄2 choke is as low as I can get it. Even when I run the throttle set screw all the way in, anything below 1⁄2 choke and it will suddenly die. Not sure if that means the idle circuit isn’t working right, or just that I have a massive vacuum leak somewhere (not that there are any lines to plug). The carb was given a new set of gaskets and small parts from a rebuild kit. Any ideas?
GeoJeepers
Via jpmagazine.com

Thanks for rescuing a flattie from the steel recycler. It’s a bit tough to diagnose at a distance, but it sounds an awful lot like a vacuum leak to us. There ain’t a ton of places you need to look on a L-head. Start with the carb-to-intake mating surface and then move on to the intake-to-engine gasket. Just spray carb cleaner at ’em and if the idle goes up, you’ve found your leak. Also, look for obvious missing plugs in the intake or a crack in the carb body. You did put the carb back together correctly—with gaskets right? They’re pretty simple to rebuild.

Write Us!
Got a tech question you’re just itching to get answered? Send it on in to Jp magazine, Your Jeep, 831 S. Douglas St., El Segundo, CA 90245, or e-mail it to verne.simons@jpmagazine.com.

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