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Your Jeep Tech Questions Answered

Posted in How To: Tech Qa on April 7, 2015
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Pentastar Swap and Cargo
I have a stock ’10 Wrangler Rubicon that does fine for my mild off-road needs. As we all know, it is underpowered. What is the feasibility of swapping out the original 3.8L engine for a newer 3.6L Pentastar found in some wrecked later-model Jeep? Is it possible, and if so, how complicated is it?

Also, I removed the back seat for more storage room. However, if I put stuff in back, it all comes crashing forward if I stop quickly or go downhill. I have looked in vain for some sort of blocking device that would keep the back stuff in back. Any thoughts would be appreciated. A friend has bolted a piece of plywood across that area in his CJ-7 using the stock rollbar as a support. The rollbar in this Jeep isn’t anywhere near the area.
Ren Colantoni
Via email

The Pentastar 3.6L V-6 found in the ’12-present Jeep Wrangler makes 83 hp more than the larger 3.8L found in the ’07-’11 Jeep Wrangler. That’s a significant amount of power and about equivalent to adding a supercharger to a 3.8L, although the fuel economy would be significantly less. Swapping a 3.6L Pentastar in place of your 3.8L really isn’t a cost-effective swap. You’ll be far better off selling your 3.8L-powered Jeep and buying a ’12 or newer Wrangler with the 3.6L already in it from the factory.

As for your storage problem, there are many aftermarket drawers, trays, and other storage solutions available to keep your stuff in place. Tuffy Security ( offers several products that may work for you, including a cargo drawer that replaces the rear seat (PN 140). The large locking and sliding drawer gives you access to all of your stuff and keeps it securely in place. Another option is to install an adjustable cargo net that attaches to the floor. Curt ( offers a couple of different sized cargo nets that could be easily adapted to your Jeep. Mopar ( offers an interesting padded storage solution called the Jeep Cargo Tote (PN 82208566). It features adjustable padded bins and rubber nibs on the bottom to keep it from sliding.

Squeaky Jeep
I have a ’00 Jeep Wrangler with a manual transmission. I have only had it a month. After about 20 miles, I started to hear a high-pitched whining. At first it’s only audible when I push in the clutch. Then it becomes constant except when I am pushing on the gas pedal. Then it is nonstop when I am stopped or when I am moving. I even had someone at a drive-through window ask me if that noise was coming from my vehicle. Even the radio can’t drown it out. We have put on a new belt and a tensioner. This did not help. What do you think?
Sharon Wainscott
Via email

It sounds as though you could have a worn clutch release bearing. Typically, when a clutch release bearing is beginning to wear out, it will only make noise when the clutch pedal is released. If you push the pedal in, the noise will go away. As the bearing becomes more worn, it will make noise all of the time, no matter if the pedal is in or out. Eventually, the bearing will fail and damage the clutch pressure plate, which would stop the clutch from functioning properly and keep you from being able to shift. Depending on how many miles are on the current clutch, it might be a good time to have the clutch disc, pressure plate, release bearing, and pilot bushing replaced. Don’t forget to have the flywheel resurfaced as well. As long as the Jeep is apart, it would be a good time to address any rear main seal or transmission leaks. A leaking rear main or transmission input seal could cause a new clutch to live a very short life.

Now, if your have the 4.0L engine with the NV3550 five-speed transmission, it may not be a worn clutch release bearing. The NV3550 is a truck-style transmission that can be found in ’00-’04 Jeep Wranglers and Cherokees. The design makes it inherently noisy. The Reverse idler shaft spins when the transmission is in Neutral. This causes a rattling noise that emanates from the transmission rather than the bellhousing area. When you put the transmission in gear with the clutch depressed, the noise should stop. The rattling from the Reverse idler is completely normal. Just make sure the transmission is filled with the proper clean fluid, and it should likely last 250,000 miles or more.

If you’re having trouble figuring out exactly where the noise is coming from, you can use an automotive stethoscope. Harbor Freight ( offers an inexpensive mechanic’s stethoscope that is easy to use. With the Jeep parked, wheels chocked, emergency brake on, and the engine running, crawl under the Jeep and poke around with the stethoscope. If you find that the noise is indeed coming from the bellhousing, it’s likely the clutch release bearing. If the noise is emanating from the transmission housing, is likely just a noisy Reverse idler.

Brake Bias
I need a proportioning valve for my Jeep. It has a stock power brake system with front discs and rear drums. I have checked the vendor ads in Jp magazine and searched online vendors. I keep running into scary reviews that state the valves last from three weeks to four months before they start to leak. I know to take these reviews with a grain of salt, since happy people don’t usually write reviews too often. I enjoy reading Jp magazine but never thought I would be asking for help. So are there any vendors that I might have missed? Also, is it possible that a valve from another year/make/model would work?
Patrick Kniskern
Via email

If you are looking for a stock-quality proportioning valve, try Collins Brothers Jeep ( The company carries older parts, some of which are NOS (new old stock). Collins Brothers also has many quality used parts available.

Personally, if it were my Jeep, I’d look into installing an aftermarket adjustable proportioning valve. When Jeeps get lifts, bigger tires, heavier axles, larger brakes, and so on, the brakes don’t need to perform the same as stock. You may need a little more or less brake bias to keep one end or the other from locking up too soon. Several companies, such as Wilwood (, offer adjustable proportioning valves that can be adapted to fit your Jeep. I’d recommend Wilwood PN 260-10922. This proportioning valve is compact and made from forged billet aluminum. The pressure adjustments range from 100-1000 psi, and it provides for a maximum decrease of 57 percent in-line pressure. The adjustment knob features fine threads for precise pressure adjustment. To install it, you’ll need to remove the factory proportioning valve and plumb the Wilwood part into the rear brake line. It will likely require a bit of brake line bending and modification, but the end result will be a much more adjustable system.

Pokey Hose
Do you have any advice on how to adapt the fuel-sending unit in a CJ-7 to AN fittings? I want to upgrade to steel-braided lines and fittings that could tolerate the 40-60 psi required by modern-day fuel-injected engines. I have a 21-gallon poly CJ fuel tank.
Geramie Parrish
Fort Worth, TX

Stainless braided lines can be adapted to almost any application and will work well on a high-pressure EFI fuel system. Hundreds of different adapters are available to make the switch to AN fittings. You’ll need to know what fittings your tank has to begin with, so you may have to drop the tank to get in there. However, you likely don’t need to drop the tank all the way. Once you’ve identified the fittings you need, head on over to Earl’s Performance Plumbing ( and find what you need in the adapter section.

If you haven’t used stainless-braided line before, you’ll quickly find out that it can be painful to work with. I always seem to get poked by the frayed braided-stainless wires when cutting the hose and installing the fittings. If you are careful when routing the fuel lines, you don’t need the stainless braided lines to get the high-pressure performance. The Earl’s Super Stock push-on hose is a high-quality synthetic rubber hose with an interior braided fabric sheath. It can be used with gas, diesel, oil, ATF, alcohol, E85, water, or as a vacuum line. When used with Earl’s Super Stock push-on hose ends, it’s capable of a 250-psi working pressure, which is well beyond what any gas EFI system produces. The Super Stock hose is easier to work with and less painful to assemble than stainless braided line. The push-on fittings and hose are also less expensive than stainless-braided hose and the required bolt-together fittings.

By chance, with your years of off-road wisdom, would you have an idea who makes front upgraded shafts for the ’79 J-10 Dana 44 (the Wide-Trac version)? I’m not having any luck in my search, and I’m worried I’ll have to go custom.
Chris Shearer

If you want to stick with the U-jointed axleshafts, there are several manufacturers that can cut blank chromoly Dana axleshafts to any length. You’ll also want to upgrade the U-joints, as these are typically the weakest point. The real downside of going this route is that as you turn sharper, the U-joints and ear assemblies essentially decrease in strength. It’s simply the nature of the single U-joint design of the axleshafts.

If you want the strongest axles available, I’d recommend going with RCV Performance Products ( axleshafts. They are made in the USA from aircraft-quality high-alloy steel and come with a no-questions-asked limited-lifetime warranty. The RCV axles feature a unique constant-velocity joint in place of the single U-joint. This offers multiple benefits, including uniform strength, regardless of what angle the tires are turned to. RCV offers axleshafts for many different applications. Unfortunately, the company doesn’t have the ’74-’79 Wide-Trac FSJ axleshafts listed on the website. However, RCV can easily cut shafts to work for your application.

There is a downside to RCV ’shafts, though. They will purge a bit of grease from the boot now and then, and it can fling and attract dirt. If you are the persnickety type and don’t like grease leaks, you have two options: You can stick with weaker U-jointed axle shafts, or you can keep rags in your Jeep to wipe the RCV axleshafts clean occasionally.

Gunky Passage
I’ve torn down and rebuilt several engines over the years and I’ve always been shocked (and disgusted) by the build-up that occurs in the water jackets of engines. Even after multiple dips in a chemical tank, it seems like the water jacket spaces in the block, are caked in corrosion. Is there a way (any product) that can clear out this build-up? I was told once, that a capful of CLR Lime-Away would do the trick, if run for a couple of days, and then the system was flushed. Maybe that would work, maybe it wouldn’t, but I wasn’t about to risk whatever those chemicals might do the gaskets and seals just to find out. So is there a product or method that will actually clean out the build-up from the water jackets in an engine?
Jason Rowley
Yakima, WA

I have heard of people using several different methods to clean out the water jackets of an engine. Usually when an engine is rebuilt, the block is hot tanked. This cleans the gunk out of the oil and water passages. If the engine is still in the Jeep, you can try filling the block with vinegar and let it soak a couple days. The vinegar is acidic and should break down the gunk in the water jackets without harming the gaskets. Some people have had success in opening up clogged water jackets by attaching a small length of steel cable to a cordless drill and rooting out the passages. Obviously, you probably won’t be able to reach them all with this method, but it may be enough to help the cooling system work properly. No matter what method you use, be sure to thoroughly flush out all the debris before refilling the system. You don’t want to clog your radiator with all the freed-up sediment.

Most of the sediment found in the water jackets comes from the minerals in the water that you put into the cooling system. To keep your cooling system as clean as possible, always use the proper mixture of coolant and distilled water instead of tap water. Distilled water is pure and has no minerals that will solidify in your engine or radiator, which allows them to live a long, cool life.

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