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

Posted in How To: Tech Qa on July 17, 2018
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Repower 4.0L

I have a ’05 Jeep Wrangler LJ with a six-speed manual transmission and my 4.0L engine just ate itself. The number six piston ring made its way into the oiling system. I’m planning on doing an engine swap with a 4.0L crate engine. I have several questions:
1. Is it better to pull just the engine and leave the transmission and transfer case in the Jeep?
2. Other than the water pump and the clutch, is there anything else I should replace now while it’s easy to get at?
3. Is there a rule of thumb on how to get the synchronizer (distributor-not-a-distributor) aligned properly? When I replaced the cam two months ago it was something I ended up having to pay someone to do.
That’s all for now—thanks for your time. Oh, and any tips or tricks I missed, I’ll gladly take too!
Darek Connole

Swapping out a worn or blown engine is usually a fairly straightforward proposition. You unbolt and pull the old one and then sling in the new one. However, there are a few things that you can do to simplify your repower swap. It’s usually easiest to pull just the engine, leaving the transmission, transfer case, and driveshafts in place. Make sure the transmission is properly supported before unbolting the bellhousing bolts and attaching the hoist to the engine. However, in some applications it may be difficult, or impossible to access the bellhousing bolts. If so, the engine and transmission can be removed as a unit, or you can pull the engine, transmission, and transfer case.

The most important thing is to make sure you have everything disconnected and out of the way. Disconnect all plugs, hoses, and wiring that are routed from the engine to the frame and body. In most cases you should be able to unbolt the A/C compressor from the engine, leaving the hoses pressurized, and place it out of the way in the engine bay. In other cases you may need to have the A/C system evacuated prior to engine removal, and then recharged once the engine and front accessory group are back in place.

You can greatly simplify the engine removal process by swinging your Wrangler hood all the way open. On other 4x4s the hood can be removed. Removing the radiator and grille and maybe even the fenders will offer greater accessibility and ease your engine replacement.

When replacing an engine, it’s always a good idea to replace the water pump, spark plugs, belts, hoses, and clutch. Don’t forget to resurface and properly clean the flywheel prior to installing the new clutch. If the transmission has a lot of miles on it or it makes unusual noises, then it’s a good idea to freshen it up. Automatic transmissions with 150,000 miles or more on them could be problematic when coupled to a new engine. It’s not at all uncommon for an old and worn automatic transmission to give up the ghost shortly after being backed up to a new engine.

The easiest way to keep the 4.0L camshaft synchronizer inline is the same as any older distributor-style ignition. Rotate both the new and old engines to the No. 1 cylinder at TDC. Set the indexing mark on the harmonic balancer to 0 on the degree markings on the block. Use a paint pen to mark the 4.0L camshaft synchronizer, internal wheel, engine block, and firewall, or anywhere that will help you get it back to the proper location during reinstallation in the new block before you remove it. It may take a couple stabs and some futzing with the oil pump gear via a long screwdriver, but you should be able to get it properly located using your marks. You can also correctly locate the 4.0L camshaft synchronizer by lining up the two holes under the top cap of the sensor using a toothpick. The toothpick is used to keep the camshaft synchronizer indexed while the engine is at TDC on the No. 1 cylinder. This should allow you to get the engine started, but you’ll likely need to time the engine 5-10 degrees one way or the other for it to run properly.

Dakota Solid-Axle Swap

I’m looking for a bolt-on straight axle swap kit for a ’99 Dodge Dakota 4x4. It has an extra cab, a 5.2L V-8, and an automatic transmission. I’m also looking for looking for 4-inch rear lift blocks and U-bolts. Can you help me?
Terry Randall

Photo: Jerrod Jones

Unfortunately, the ’97-’04, and pretty much all of the Dodge Dakota and Durango models, never enjoyed an abundance of aftermarket support. I don’t know of a kit to do what you propose. A bolt-on solid-axle swap kit would require a lot of time and effort for a company to develop, both of which are typically reserved for more popular 4x4s. The initial investment would likely never be recouped. But don’t fret, there may not be a bolt-on solid-axle swap kit available for your Dakota, but lots of people have performed the conversion at home in their own garages. If fabrication is not your strong point, you may be able to use solid-axle swap components that were designed for other vehicles to help you complete your conversion. Of course, these parts will need to be modified to fit your Dakota, but they will help solve some of the bigger problems of starting from scratch. Companies such as Offroad Design (, Off-Road Direct (, RuffStuff Specialties (, Sky Manufacturing (, and WFO Concepts ( offer kits and individual components that could help you with your conversion. If customizing a kit is beyond your expertise, you could always have a fabricator do the work for you, or have the fabricator build a custom one-off kit. For example, WFO Concepts has a project Dodge Dakota with a solid-axle swap you can read about online.

As for the rear lift blocks, you should be able to utilize any universal 2.5-inch-wide lift block kit with the proper-size U-bolts that fit your axlehousing and spring plates. Companies such as Rough Country ( offer universal 2.5-inch-wide lift blocks and a variety of different U-bolt sizes to work with nearly any application. You need to measure your existing U-bolts and axlehousing tube diameter to get an idea of exactly what you will need to put the blocks between the leaf springs and the rear axle.

Diesel Death

I’m not a huge fan of Ford, but I’m interested in your opinion of the ’18 F-150 with the 3.0L Power Stroke diesel. Have you driven the Ram EcoDiesel? I’m wondering how they compare.
Shawn Hambrick

I have only spent a limited amount of time in the ’18 Ford F-150 with the 3.0L Power Stroke, but I have spent quite a bit of time in the Ram 1500 with the 3.0L EcoDiesel. Personally, I think the eight-speed automatic in the Ram 1500 EcoDiesel truck does a better job managing the diesel power than the ten-speed automatic does in the Ford F-150 Power Stroke. It could be the gearing, or it could be the transmission computer. I just think the Ford ten-speed could use some improvement.

I wouldn’t consider either truck a heavy hauler. That job would likely be done better with the V-8 versions of these trucks, although the diesel engines provide a calmer and less peaky towing experience than the currently available gas engines.

Ultimately, both the Ford F-150 Power Stroke and Ram 1500 EcoDiesel do what they are designed to do, which is provide fuel-efficient diesel torque. However, that increased torque and fuel economy comes at a cost. Regardless of what most people believe, the optional 1/2-ton diesel engine cost will probably never be recovered at the fuel pump. Both the Ram and Ford 1/2-ton diesel engines have been boogered up with emissions systems. The DPF particulate filters decrease the fuel efficiency of the engines and the diesel exhaust fluid (DEF) systems add cost and complexity. For a typical person that drives around 12,000 miles a year, it would take between 7 to 70 years for the increased diesel fuel efficiency to pay for the diesel engine option, and that’s not even taking into consideration the cost of the required diesel exhaust fluid or the more expensive diesel oil changes. The current emissions laws could very well be the downfall of the diesel, at least in smaller vehicles and 1/2-ton pickups.

Manual 4L80 Update

I recently read “Build a Bombproof 4L80 Manual Valvebody Transmission” on Did the shop that did the conversion use a kit? If so, which one? Did you have harsh shifting or did the valvebody control the line pressure properly? Overall, were you happy with the conversion?
Kurt Matthew Brown

Well Built Transmissions ( assembled our full-manual valvebody 4L80 GM four-speed automatic transmission using rebuild parts supplied by Monster Transmission ( and a manual valvebody from Culhane Racing Transmissions ( If you are unsure of if you can do the work yourself, Well Built Transmissions can assemble a transmission for you and ship it pretty much anywhere.

Our manually shifted 4L80 transmission made its way into a go-fast desert truck that sees some street use and high-speed mountain trails too. The truck features a 4,000-rpm stall converter, 5.00:1 ratio axle gears, and 37-inch tires. The truck’s owner is really happy with the manual valvebody. However, there are a few things to consider before ordering parts or a complete transmission. The valvebody needs to be modified to match torque converter performance. You’ll need to know the stall speed of your converter before ordering a valvebody from Culhane. Shift firmness can be altered by Culhane to meet your needs.

We retained the lockup feature of our torque converter for use on the highway. It’s connected to a toggle switch. If you leave the converter locked around town, you’ll need to shift to First gear before coming to a stop. Only shifting to First gear will automatically unlock the converter. Leaving the transmission in any other forward gear when coming to a stop will cause the engine to stall. The torque converter is generally left unlocked when driving off-road.

The Culhane valvebody essentially turns your 4L80E into a semi-automatic manual transmission. If it seems like too much shifting for you, then you might want to retain the factory automatic shifting features of the 4L80E.

Firewall Fab

I’m building a single-seat buggy from a dirt modified chassis. I’d like your input on the firewall. The only thing mounted to the firewall will be the throttle pedal and brake pedal assembly, which will also be supported from a tube above it. I have 1/4-inch aluminum plate and 3/16-inch steel plate that I can use for the firewall.
Ken Basile

If you are working with a tube chassis, you’re likely trying to at least keep an eye on overall weight. A firewall made from 1/4-inch-thick aluminum or 3/16-inch-thick steel plate will be incredibly heavy. Both materials are commonly used for things like skidplates underneath. I think that you’ll be better off with something like 0.050-inch-thick aluminum or 20-gauge steel sheetmetal. At the most, you could consider 0.125-inch-thick aluminum if you insist on mounting the throttle pedal directly to the firewall. However, I would recommend building a mount that sandwiches the firewall and attaches the throttle pedal to the chassis. The brake pedal assembly and master cylinder should be mounted directly to the chassis and not the firewall in your case.

Speedo Corrector

My truck is a ’85 Chevy K10 with a 2-inch lift. It rolls on 33x12.50 Dick Cepek tires and has 4.10:1 ratio axle gears. It’s powered by a 350 V-8 and a 700-R4 automatic transmission in front of an NP208 transfer case. My speedometer is off by about 5 mph between 0-30 mph and 10 mph between 30-70 mph. If the speedometer reads 30 mph, the truck is going 35 mph. If it reads 60 mph it’s going 70 mph. I downloaded a GPS speedometer app on my phone to check the accuracy. Do I have the right gearing or do I need to change the speedometer gear in the transfer case? Your expertise would be greatly appreciated.
Danny Vasquez
Via email

Altering the tire diameter and or the axle ratio will require the speedometer on any 4x4 to be corrected. Fortunately, the NP208 in your GM truck features a traditional mechanical speedometer output and cable that operate the speedometer in the dashboard. The NP208 also features a two-gear speedometer output that offers quite a bit of adjustability. It looks like your speedometer is about 16 percent slow, which could easily get you a ticket if you aren’t paying close attention to your actual speed. To correct this problem you’ll need to remove the speedometer housing on the NP208 to find out what speedometer drive and driven gears your transfer case currently has. This will help you to purchase the new gears you need. Companies such as LA Speedometer Gear ( offer a full line of new gears to get your speedometer all sorted out. The company can also help you calculate what gears you need.

Your other option is to use a speedometer drive adapter, which threads inline on the speedometer cable and alters the cable speed. Unfortunately, this type of adapter will almost never make your speedometer 100 percent accurate, but you can get closer than it is now. You would need a speedometer drive adapter that would speed up your speedometer about 16 percent. There are adapters available that will speed it up by 11 percent and a different one that will speed it up by 20 percent, so you are kind of in the middle. You will have to decide which way you want to go. Speedometer drive adapters are available from companies like PATC (

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