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Answers to all your Jeep questions

Posted in Features on August 10, 2015
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Real Time Temp

As you likely already know, the stock gauges in YJ Jeeps are not accurate—especially the temperature gauge. Mine is not at all steady and is constantly moving up and down. Replacing the sensor and gauge did not help. The stock sensor location at the back of the head is too small for a mechanical gauge probe. Every mechanical gauge I have found has a 3/8-inch NPT pipe thread. I have read in forums that many people are trying to find a way to do this. I have heard of putting the probe in the heater inlet hose or the top radiator hose. I have also heard of people drilling and tapping a 3/8-inch NPT sensor hole on top of the head in the rear. I don't like not knowing what the real-time engine temperature is. Any suggestions?
Larry Burke
Via email

I have had similar problems with both factory and aftermarket electric temperature gauges. Sometimes it's simply a poor ground at the sensor caused by too much thread sealant or corrosion. Other times it's a pinched or melted wire or a damaged sensor plug. Regardless, like you, I hate depending on the tiny and delicate sensor wires for knowing something as critical as the correct engine temperature. Whenever possible, I try to use a mechanical temperature gauge. But, as you have found, there isn't always a spot on the block or heads to thread in the large sending unit commonly found with mechanical temperature gauges. Fortunately, there are a few products available from Auto Meter (autometer.com) that can help you get a mechanical temperature sending unit in place on just about any engine. Auto Meter offers weld-in, thread-in, and inline hose adapters for the mechanical temperature gauges. In your case, the radiator hose adapter might be the best option. These are available in a 1 1/2-inch (PN 2283) and a dual-size 1 and 1 1/4 -inch adapter (PN 2282). It's basically an aluminum fitting that can be spliced into your existing radiator hose. The adapter features a 3/8-inch threaded NPT port specifically for a mechanical temperature gauge. You simply cut a small section from your return radiator hose and insert the hose adapter using the two included hose clamps. A ground wire is included for use with electrical sending units. Carefully route the mechanical sending unit cable and avoid any sharp bends. Kinks and bends can damage the cable and keep the mechanical gauge from working properly.

Tranny Troubles

I have a '00 TJ Wrangler Sahara with a 4.0L inline-six and an automatic transmission that will not go into Third gear correctly. The torque converter will not lock up unless I let completely off the throttle or modulate it. It happens anytime the Jeep sits for a day or more. After a few miles, everything starts working fine. The service manual says the lockup converter only comes into play for Third gear. No one will touch this 32RH for a rebuild, and I only found one used online for over $1,000. No codes have ever been tripped and the tranny works flawless except for no kick-down when I floor it. I'd hate to replace the transmission with only 124,000 miles on it. I recently read an article in Jp about replacing the converter.

Do I risk just replacing the converter (which I can get) or go for a used tranny? I know these things don't last much over 120,000 miles, but mine has never had a hard life.
Ray Beeson
Apple Valley, CA

That's a tough call. Clearly there is something that isn't working right. It could be any number of things or multiple problems. My best advice would be to let a competent transmission shop take a look at your Jeep. Someone that knows what they are looking at will have a much easier time figuring out what is going on. I once had a transmission that I was sure was toast. It had all the signs that something had been smoked inside. It was slipping and would not shift properly. I started with the simple stuff myself, checking vacuum lines and electrical connections, and found nothing out of place. I took it to a competent shop where they dropped the tranny pan to take a closer look. They found that several of the transmission valve body bolts had come loose. They tightened them up, changed the fluid and filter, and the transmission worked as good as new. Now, I'm not saying that's what's wrong with your transmission—it likely isn't. However, getting your transmission in the hands of someone that runs into these problems often is a good bet, especially because you have more than one issue. Simply tossing in a new converter may solve the problem with the lockup issue, but you could be pumping metal bits through your brand-new part if the transmission has other issues. Give all of the transmission wiring, plugs, hoses, and other connections a good looking-over first. Then head to the shop if you can't find any problems.

Perfect Jeep Replacement

I want your opinion and thoughts on the "perfect" Jeep for my situation. The year, model, and so on doesn't matter as long as it's an automatic. This Jeep will be mostly used by my wife. It will be used mostly on-road. It has to be something reliable enough to be driven across the country if need be, but strong enough for getting through the Colorado snow and a trail or two. She is currently driving a '88 Grand Wagoneer and loves it, but it's pretty much worn out and needs to be replaced.
Doug Bridges
Estes Park, Colorado

You didn't specify if you wanted a used vehicle or a new one. Given the size, weight, and capability of the vehicle she is currently driving, I think the '99-'04 Grand Cherokee is a good choice if you are looking for a used higher-mileage Jeep. The 4.0L inline-six engine will hold up better than the much more complex 4.7L V-8 over the long term. The '05-current Grand Cherokee is also a solid choice. Several different engines were available during that time period. In no particular order, I would put the EcoDiesel 3.0L V-6, the Pentastar 3.6L V-6, and the 5.7L Hemi as my top engine picks. For fuel economy, go with the EcoDiesel. For a compromise on fuel economy and power, go with the Pentastar. And for pure muscle and hauling capability, get the Hemi.

Another option that many past Jeep owners have embraced is the '07-current four-door Wrangler Unlimited. If you were to go that route, I would recommend getting the '12-current version with the Pentastar 3.6L V-6 engine. The extra 83 hp and interior amenities will be worth it.

Suspension and Engine Options

I have been a CJ man all my life. I have a girlfriend with three kids, so I eventually let my Jeeps go, but I have a few bad disks in my back. I like the simplicity of the CJ, but the ride is a little too harsh for me now. Is a coil-spring suspension that much better? Can I put coils under a CJ? Can a TJ's running gear bolt up to a CJ body? What do you think is the best six-cylinder for a daily driver that sees light to medium trail duties, the 4.2L, 4.0L, or maybe a 4.3L Chevy V-6? Does the left/right front pinion position cause any problems?
Mike
Via email

The simple answer is yes: the coil-sprung Jeeps ride a lot better than the old leaf-sprung CJs. However, it is totally possible to screw up the ride of a coil-sprung TJ or JK by installing the wrong lift kit and shocks for how you plan to use the Jeep. In your case, I would stick with smaller lifts and lightly valved or adjustable shocks set to the softest setting. You can make a huge difference in ride comfort by installing suspension-style seats like those from Corbeau (corbeau.com), MasterCraft (mastercraftsafety.com), and PRP (prpseats.com). I have had many people with bad backs tell me that suspension-style seats were the only thing that allowed them to be able to drive off-road again. The suspended seats dampen the harsh and jarring compression that standard foam seats can't.

You can put coils under a CJ; however, it would be very cost prohibitive. They will not simply bolt in. It would require the fabrication of a completely custom suspension. For about the same price of that custom suspension, you could buy a good used Jeep TJ Wrangler.

As for the engine, it's hard to beat the reliability and performance of the Jeep 4.0L. However, the inline-six is based on a 50-plus-year-old design. If we are talking about swapping engines into a CJ, for best all-around performance and fuel economy, I think you might be better off with a modern fuel-injected 4.3L GM V-6. Really, though; either of these two engines are good choices. The 4.2L inline-six is simply too antiquated. It would cost quite a bit to install fuel injection, a modern ignition, and so on. The resulting performance would be less impressive than a more modern and less expensive fuel-injected 4.0L.

A CJ frame can be made to accept a driver-side drop front axle and drivetrain fairly easily, but it's not a simple bolt-in procedure. Fabrication, cutting, and welding would be required to complete an engine, transmission, transfer case, and axle swap of this magnitude.

Cooling Flatfenders

I am building a flattie. It has a 4.1L Buick engine in it. Does the M38 grille have more radiator room than a typical flatfender?
William Lawson
Via facebook.com/JohnCappa4x4

The M38, CJ-2A, and CJ-3A all have about the same space for a radiator. Unfortunately, the large, 7-inch round headlights and the factory headlight buckets take up a lot of space behind the grille. The MB/GPW grille offers more radiator room. The headlights are smaller and the grille has nine open slats instead of seven, offering more surface area and potential airflow. However, the factory flip-up MB/GPW headlight buckets take up a lot of space and can get in the way in some cases. In all cases, I've found that you can fit a larger radiator if you don't use the factory headlight buckets—or at least trim them. No matter what grille you choose, you'll likely need to remove or modify the stock shrouding that is spot-welded to the backside of the grille.

How large of a radiator you can fit will be dependent upon many factors. The engine location, steering linkage and shaft, and whether or not you have the factory front crossmember are all important variables. It's possible to fit a 27-inch-wide by 16-inch-tall universal aluminum two-core radiator behind a flatfender grille with trimmed headlight buckets. Flex-a-lite (flex-a-lite.com), Griffin Thermal Products (griffinrad.com), and Summit Racing (summitracing.com) offer many different universal radiators that can made to work. I've actually been eyeballing the smaller 24x15.5-inch Griffin Combo Unit (PN CU-25201-XS) for one of my flatfender projects. It is rated for up to 400 hp and comes with an electric fan and fan shroud.

The engine location is key. On some engines, like the Chevy small-block you will have to modify the firewall to fit the large HEI ignition. Surprisingly, it fits, even with a long water pump. However, this extra-long combo is not ideal. Since building a flatfender is sort of like putting a puzzle together, you'll want to experiment with engine location before burning in the motor mounts and transmission crossmember. Moving the engine too far forward won't leave enough room for a radiator and fan, and moving it too far back will result in a very short rear driveshaft. Fitting your Buick engine should be much easier than fitting and cooling a small-block Chevy.

Proper airflow is very important for your cooling system to function properly. A mechanical fan attached to the water pump can move massive amounts of air. However, the fan and radiator will require a good shroud to make use of their capability. If the engine is mounted too low, a mechanical fan will be almost worthless to you unless you have the ability to build a complex shroud. Even then, the fan could make contact with the steering linkages under full suspension compression. If you find that you can fit a mechanical fan, Flex-a-lite offers rigid steel race fans that move lots of air through your radiator when properly shrouded. They do sap a bit of power and make a lot of noise, though.

The flatfender grille that likely offers the most cooling potential is the slat grille. You likely won't find a used one because they are somewhat rare and valuable. However, you could easily build one by bending and welding together 3/4 or 1-inch-wide strip steel. They are sort of ugly but certainly original looking. Omix-Ada (omix-ada.com) offers all the old Jeep grilles, including the MB/GPW (PN 12021.99) and slat grille (PN 12013.01). A flatfender grille swap is a bolt on conversion if you decide to go this route.

Side by Side Seating

I am nearly done with the sheetmetal work on the tub of my flatfender Jeep. I moved the top of the wheel house up a couple inches to maximize tire room with minimal lift. I also pushed the bottom of the forward edge back 2 inches and the top back 4 inches to maximize seat room. What model PRP seats are you using in your flatfender? I need to buy a set for my project and I'm trying to make a decision. I was considering the PRP Rhino seats or the MasterCraft PWRsport seats.
Corey Ferguson
Via facebook.com/JohnCappa4x4

Fitting seats in a flatfender so that you are comfortable and still able to operate the controls can be a tricky task. The body metal mods you have made will help considerably. Both MasterCraft (mastercraftsafety.com) and PRP (prpseats.com) offer quality suspension seats. I have been fairly successful at fitting PRP Premier Series low-back seats in two different flat-fender Jeeps. These seats are 24 inches tall, 22 inches wide, and 26 inches deep. The PRP Rhino low-back seats can be used for those looking for a little more room. They measure 24 inches tall, 22 inches wide, and only 23 inches deep. That extra 3 inches can go a long way in making entry and exit a lot easier, as well as allow more legroom to operate the pedals. To fit my fullsized Premier Series seats, I bashed the base of the wheel wells back just a bit. I also built mounts that tilt the seats back to about 15 degrees. This makes it more difficult to get in and out of, but the seats cradle you really well once you are in there. It's incredibly comfortable, at least for me. I'm 5 foot, 11 inches tall and about 195 pounds.

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