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Techline: Your Top 4x4 And Off-Road Tech Questions Answered Here

Posted in How To: Tech Qa on March 26, 2019
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Unlimited Overheating

I’m having a bit of an overheating problem. Hopefully, you can give me a good solution. First off, here’s a quick overview of my Jeep. It’s a ’16 Jeep Wrangler Unlimited with 37-inch-tall tires and stock 3.73 gears. It has a Rock Hard 4x4 cage, Warn Zeon winch, underbelly skidplates, rocker guards, bigger brakes, and so on. Essentially, it’s a pretty heavy Jeep. I have a Superchips F5 tuner for adjusting tire size and my coolant is good and full. I live in Colorado Springs, Colorado, and even on days when the temperature doesn’t go above 50 degrees F, I can sometimes see 235 degrees F on my gauge. This usually happens when I’m in stop-and-go traffic, from stoplight to stoplight, or going up bigger hills. As soon as I crest a hill, or traffic moves nicely and smoothly, the temp will quickly drop down to 200-210 degrees F (what I believe is normal operating temp). Here are my theories on why I get such high temps:
1. My Warn Zeon is mounted on a Crawler Conceptz bumper and blocks airflow.
2. The stock gears are really making the engine push hard in uphill or quick stop-and-go traffic.
3. The altitude (6,000-plus feet) has something to do with it.
I’d love to hear what you think.
Jake Lewis
Via email

The good news is that your Jeep isn’t technically overheating. That actually happens above 250 degrees F and can cause serious engine damage. We would start with the basics. First, give the radiator a thorough cleaning and make sure that the fins are not packed with dirt. Wash it carefully from the front and back (inside of the engine compartment). We know it sounds like a duh-huh thing to do, but you’d be surprised how easily the radiator can hoard dirt.

Second, check the electric fan. If it wasn’t working at all, you’d have serious overheating issues, so we’ll assume that it’s probably OK. Just double-check that none of the blades are damaged or the housing isn’t cracked. If the fan and radiator are in good condition, take a quick look at the coolant level.

You mentioned the coolant is good and full. Have you changed it recently or did you just give it a once-over? Your Jeep uses a specific OAT (Organic Additive Technology) fluid type. If mixed with the wrong type of coolant, it could create a blockage or buildup in the coolant jacket, or worse, on the water pump itself. Now that those are out of the way, we can get to your three points.

Yes, blocking the grille can most certainly contribute to overheating. Obviously, an easy way to check if this is the culprit is to remove the front bumper. It’s a little bit of a time commitment, but it can take that factor out of the equation. After checking out the bumper online and looking at your specific setup, we’re doubtful that it would be your sole culprit.

The stock 3.73 gears coupled with 37s are putting more strain on your Wrangler than anything else. Your Jeep came with a pretty modest 30-inch-tall tire from the factory. A 37-inch-tall tire is not only taller but also much heavier. This equates to a tremendous amount of strain on your powertain. This is going to cause your JK to work harder, which equates to more heat being generated.

Factoring in the stock gears with the elevation, we’d say these two items are likely the biggest factors in your temperature issues. No matter if it’s the root cause of your overheating or not, we would suggest re-gearing your Jeep. It will reduce strain on your transmission and engine significantly. Typically, we like 5.13 gears with 37s.

Another quick note about programmers: Some actually allow you to modify your electric fan settings, so it will come on at a lower temperature. This can help with low-speed cooling.

Power Wagon Locker

I have a question regarding the AAM 11.5 rear axle for Ram trucks. I have a ’12 Ram 2500 with a Cummins diesel and six-speed manual transmission. Starting in 2014, the Ram Power Wagon’s rear axle was upgraded from the 10.5 to the 11.5 AAM axle. The rear axle in the Power Wagon gives you both a helical gear limited slip and a selectable electronic locker. To me, that is the perfect differential. You get a limited slip for the street and you can lock it went the going gets rough.

No one else makes a carrier like that. You either have to buy a limited slip, auto locker, or a selectable locker, which runs as an open diff when not locked up. My question is, can you install the carrier from a ’14-up Power Wagon 11.5 axle in a standard Ram 11.5 axle with some modifications (i.e., hole for the locker wiring and wiring up switches to engage the locker)?
Laurence
Via email

The TracRite GTL is a pretty novel best-of-both-worlds differential. It’s made by AAM, so we visited the company’s site to get more information on the locker. Interestingly enough, AAM doesn’t list the TracRite GTL for the 11.5—only for the 10.5. Obviously, we know the ’14-and-newer Power Wagon is running the TracRite GTL, but there could be more to the story here. As in it may be difficult to source one, or you might have to pony up for a dealer-only parts order. That being said, we can’t find any reason why the TracRite GTL in the Power Wagon will not work in your standard 11.5 rear axle.

Tundra Locker

I have a ’00 Toyota Tundra that’s two-wheel drive. I plan on keeping this truck until I die. But, I live in Kentucky and at times I need better traction than what I have. I would like to know what locker for the rearend you would suggest. Also, do you know of a reputable shop to do the work? I live near Elizabethtown, Kentucky.
Ed
Via email

First, there are a few off-road shops near you in Kentucky to choose from. We’ve actually spent some time wheeling with and checked out the builds at Moab Offroad (moab-offroad.net) in Louisville, Kentucky. In terms of a locker, you are in luck. ARB offers an Air Locker for your Tundra’s rear axle (part number RD129). This is a selectable locker that works as an open differential when not engaged. When you need it, simply flip a switch and it becomes a full spool-type locker, completely engaging both rear drive wheels. You will need an air source for this locker, such as a small air compressor or onboard air tank. ARB sells a relatively compact air compressor that’s a great fit for the locker.

JK on the Low

I picked up a new-to-me ’14 Jeep Wrangler Unlimited a few months ago. It has a small lift and 35s. So far, my wife and I really like it, but it’s a bit on the tall side for getting in and out of every day. We enjoy going off-road, but nothing too extreme. It’s a Sport, so it didn’t come with any type of rocker protection. In fact, we don’t even have the plastic steps that I see on some other models. I’d like to get something to make getting in and out a little easier, but I don’t think a regular step will work off-road. It seems like most of the rocker guards or slider rails sit too close to the body to be used as steps. I know from past experiences with my TJ that regular bolt-on step bars are not strong enough. Do you have any recommendations?
Tim S
Via email

There are quite a few rocker guard options for the ’07-’18 Jeep Wrangler Unlimited, but the ones that might make the most sense for what you are trying to accomplish are from Rock Slide Engineering. They are simply called Step Sliders, and they work as both a rock slider and retractable step. The manufacturer states they attach using stock mounting points, so that part of the install appears to be pretty easy. The big advantage of these is that the step drops down a full foot when you open the door and can support 650 pounds. Once you are back in the Jeep, it automatically retracts. For a daily driver that you plan to wheel, it’s a great fit. You can check them out online at rockslideengineering.com.

1350 vs. 1310

I’m about five months into to my ’91 Ford Bronco build and have come to the point of needing to get a new set of driveshafts. It has the 351ci V-8, C6, and BorgWarner 1356 transfer case. The axles came out of an older radius arm Bronco (Dana 44 front and 9-inch rear). My question pertains to driveshafts. After talking with my local driveline shop, it looks like my original driveshafts have 1310 U-joints. I’m thinking it might be a good idea to go up to a larger U-joint size, but I’m not sure if it’s worth it. I have V-8 power, but I’m a conservative driver. Any advice is appreciated.
John B
Via email

First off, that sounds like a cool project! The 1310 universal joint is one of the most commonly used throughout the 4x4 world. It’s compact and fairly strong. However, in a fullsize application such as yours, we would rather opt for the 1350 if we had the choice.

Comparing the point of elasticity between the two, the 1350 can withstand an additional 660 lb-ft of torque. In the instance where you’ll need a CV-style driveline, you’ll be able to get a few more degrees out of the 1350 as well. This will reduce the likelihood of the driveline binding at full downtravel. Keep in mind that CV drivelines work best when set between 10 and 12 degrees.

Another important factor to consider when building a new driveshaft is the tubing itself. Your stock drivelines were never designed to grind along an obstacle off-road, so it doesn’t take much to bend one out of shape. Many aftermarket ’shafts use 2-inch-diameter DOM tubing with a 0.120-wall thickness. However, you can get thicker 0.180-and 0.250-wall tubing. The trade-off with wall thickness is mostly power loss.

At the end of the day, moving up to 1350 U-joints will cost you a little more initially, but the peace of mind on the trail is well worth it.

Diesel Swapping

Every time I go to my local pick-a-part, I always cut through the import section. Recently, they got in a handful of older diesel-powered Mercedes. I don’t know why, but I like the idea of an oddball diesel swap. I have a ’76 Jeep Wagoneer that hasn’t run in a while and might be a cool candidate for a cheap diesel. One of the engines is naturally aspirated and the other two are turbocharged. Both are five-cylinder inline motors. Is there any particular one I should look for or is this a waste of time?
Charles Lee
Via email

What you’re mostly likely seeing is the OM617. These were used throughout the 1970s and 1980s. It’s a 3.0L engine that is known for reliability and longevity. In fact, we wouldn’t be surprised if all the cars you are seeing will have north of 300,000 on the odometer. This engine swap has definitely become more popular over the past decade. The cylinder heads and block are both made from cast iron, so it’s fairly robust and heavy. Obviously, pulling an engine from a pick-and-pull is a bit of a gamble. We would want something like this gone through thoroughly before we made the effort of putting it under the hood. The big thing we would keep in mind is that these engines were not very powerful (the non-turbo models even less so). Expect to see around 120 hp and 180 lb-ft of torque.

The Wagoneer has a fairly large engine bay, which is going to be needed for the long inline. We’d also plan on adding a bit of frame reinforcement for the heavy diesel engine. Ultimately, if you’re looking for a reliable and inexpensive diesel, it’s not a bad option. Just don’t expect it to make lots of power without spending some serious money.

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