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Diesel Tech Questions

Top Tech

Bruce W. Smith
Aug 30, 2017
Photographers: Bruce W. Smith
Photo 2/5   |   Cardone’s 6.7L Cummins water pumps (PN 5531412) are manufactured using both plastic and cast-iron impellers. Most are built with the OEM-specification plastic impellers, with a few coming off the assembly line with the more-sought-after cast-iron version.

A Mixed Bag

In your August ’17 issue, on page 128, Phil Blake sent you a letter about his truck’s 6.7L Cummins engine overheating, and you told him to get a Cardone Industries pump (PN 5531412) that has roller bearings with a cast-iron, seven-blade impeller. I ordered one from Cardone and received a pump with a plastic impeller. Did you give out the wrong part number?
Sodbuster
via email
The part number is correct. We contacted the customer service/tech department at Cardone Industries about Diesel Power readers finding plastic impellers on replacement water pumps they ordered. Steven Tortu Jr., a representative of Cardone’s technical support team, says “Part Number 5531412 is a consolidation unit, therefore it will come with either a plastic or cast-iron impeller. We mostly use plastic impellers, but there are some cast out there. We try to use the plastic impellers as much as we can because that is based off of the factory specification. There is no specific way to determine which of our pumps have the cast impellers.” For those of you seeking the cast-iron gems, this means you may have to dig through your local parts store’s inventory of Cardone’s Cummins water pumps until you find one fitted with a cast-iron impeller.
Photo 3/5   |   Slipping a Cummins or Duramax engine into older GM pickups with the 6.5L diesel can be done so cleanly that the new engine almost looks factory-installed. But such swaps take a lot of pre-planning, a thorough understanding of electronics, and a thick wallet, depending on which transmission is backing up the new engine.

GM Cummins Swap

I am inquiring about the topic of swapping either a 6.6L Duramax or a 5.9L Cummins engine with an Allison automatic transmission into a ’95 6.5L diesel-powered Chevrolet 3500 dualie. I’m wondering if you would have any information that will help me execute the swap, or thoughts on which one will be better?
Duane Kaiser
via email
Either swap gets a thumbs-up in our book, compared to running that old oil-burner. We covered transplanting the Cummins/Allison combination in an ’02 Ford F-250 (“Big-3 Blend,” June 2017). But, as that series of articles shows, there’s a lot of planning that’s necessary when doing a cross-brand conversion—not to mention the time and expense required.
We contacted Diesel Conversion Specialists in Kalispell, Montana, to get the inside scoop on what they think is the best route to take. The company has the parts and expertise to make the Cummins-into-GM swap a reality. Brian Hollingsworth provided us with details that can help with the decision making:
“While a lot of things factor into determining which conversion is your best option, the single biggest influence, of course, is how you plan to use the truck. Being a 1-ton dualie, it’s probably going to go to work every day and maybe even do some towing. If you are doing all the work yourself, a 5.9L 12-valve Cummins engine with a VP44 injection pump (or a P-pump if you can get one) backed by a GM 4L80E automatic transmission is probably the simplest package that will get the job done. This combination doesn’t require a lot of wiring, but a separate controller for the transmission is needed. It won’t make a ton of power, but it is reliable, and it’s the least-expensive combination to maintain.
The 24-valve 5.9L Cummins engine is very reliable, makes more power than a 12-valve, has mechanical injectors to keep maintenance costs down, and can easily be wired to run as a standalone in any vehicle. However, 24-valve powerplants require a transmission controller and an auxiliary fuel pump to feed the injector pump, which, of course, brings additional expense to the project.
The common-rail (5.9L/6.7L) Cummins is extremely popular as a conversion engine, as it’s quieter, makes plenty of power right out of the box, is easy to make run as a standalone unit, and seems to have no limit for performance potential. But all of that comes with a high price tag. Although the engines aren’t terribly expensive, it’s the actual conversion setup and support that has a high price tag. Common-rail engines have more nuances and a higher general maintenance cost, and they are more complicated to troubleshoot when there is a problem.
Depending on the year of the engine and how you want it to run, you need the engine harness, TIPM, ECM, and throttle pedal at minimum. If you aren’t savvy with wiring (and there’s a lot of it), that means you will have to take the engine harness to someone to have it modified. Then it has to be tuned, and you’ll need to install a lift pump.
If on top of that you choose to back it with an Allison transmission, there is the cost of the unit, plus all the additional wiring, the controller, and tuning to make it shift properly. Additionally, we believe the transfer case on the ’95 is a 32-spline and the Allison is 29-spline, which requires changing the output shaft on the transmission or swapping in an NP261 transfer case. Either option may require some driveline modifications. This isn’t to dissuade anyone from running a common-rail Cummins and an Allison in a GM, because when they’re plumbed and wired correctly, they’re a great package. But it’s those not-so-obvious puzzle pieces that drive up the price of a conversion considerably.
The other challenge with the common-rail is fitment: 6.7L is similar to the 24-valve 5.9L, but it’s slightly bigger in enough places to make it a genuine chore to fit it all under the hood of a Chevy 3500. The front crossmember must be modified in order to get the taller Cummins down into the engine bay.
All the Cummins conversions require adapting some ancillaries (power steering, HVAC, sensors, and such) to work with the truck’s dash instrumentation. An intercooler and plumbing are necessary for all Cummins engines except the rotary-pumped powerplants.
The other alternative is staying with GM parts throughout and installing a 6.6L Duramax engine with the Allison transmission, which initially sounds easier than shoehorning in an I-6 Cummins. The installation can be accomplished with OEM parts, and the truck can be taken to a GM technician for service. All the Duramax-based options are fully electronic, however, so if you are doing the conversion yourself, note that wiring will be the biggest challenge.
A final option is to buy a standalone harness for the engine and the transmission, integrate it into the early truck, and calibrate the ECM accordingly. The best way to pull off a Duramax/Allison swap is to score a late-model donor truck. The newer the truck, the more desirable the powertrain is for this swap, as it affords you the convenience of being able to snake some of the wiring out so you can reuse it or have it modified.
Duramax LB7 and LLY engines and wiring harnesses are the easiest to deal with when it comes to rewiring. Their installation is about the same as that of LBZ or LMM powerplants, but they just get a lot more complicated when a six-speed Allison is in the mix. If you don’t have an Allison and already have a 4L80E, you can use off-the-shelf GM parts to put together a Duramax/4L80E combination, and the shift linkage won’t require any changes.
Photo 4/5   |   The aluminum-bodied ’17 Ford Super Duty brings along all the same body features as its ½-ton brother, including the lighter-weight tailgate. Unfortunately, the accessories are not a direct fit for the older Super Dutys.

“Alumaduty” Tailgate Swap

I ran across a slightly damaged take-off ’17 F-250 tailgate at a Ford dealer that’s gathering dust in its parts department. It’s also painted the same color as my ’12. I can buy it for what the Ford backup camera system alone would cost. Will it fit my truck? I’d love to have the tailgate assist, step, rear camera, and electric locks. I can handle the wiring with help from a buddy at a car-audio shop, fix the tailgate’s bent corner, and change the latches on my truck if needed.
Will Parks
via the Internet
Hate to dampen your enthusiasm, but you should take a very close look at your truck’s tailgate and note its measurements with tape. We think the new Super Duty’s aluminum tailgate is both wider and shaped differently top to bottom than the gates on its predecessors. The pre-aluminum tailgates have a slight curve, while the new pieces are flat, and they’re 64 inches across, whereas the older ones are slightly more than 63 inches at the bottom and top. If the dealer has a body shop on-site, technicians should be able to confirm those dimensions. But it would be cool indeed if the later gate can be a direct replacement for the old steel versions.
Photo 5/5   |   Industrial Injection Diesel Performance’s Hot-Rod VP44 injection pump is a good, reliable upgrade that supports up to 700 hp. P-pumps are better, but the conversion cost can run upward of $5,000.

VP44 or P-Pump

I have an ’01 Dodge Ram 2500 with the six-speed transmission. I've owned the truck for five years, and now the VP44 injection pump is finally closing the curtains on me. I was hoping for some input about which pump to install on my truck. A lot of folks around here are ditching the VP and putting the P-pump on their rigs. I personally would like to stay with the VP for its electronic tuning advantages. But I'm not sure which one or how reliable either of them is going to be versus a replacement stock unit or a Hot Rod version from Industrial Injection. I have made some small modifications to the truck: Edge Juice with Attitude CTS programmer, 125hp injectors from Mountaineer Diesel, a cold-air intake, and a 4-inch turbocharger-back exhaust, but I plan to do more in the future.
Matt Pennington
via email
That’s a question a lot of our readers who have made small upgrades to their early Cummins-powered Rams ask. It’s also one Alec Hembury at Industrial Injection Diesel Performance fields almost every day. He says the Hot Rod VP44 is a great option for increasing horsepower with that setup, as well as having room to move into the high-700hp range. “VP44 technology, and how those pumps are put together, has come a long way. We are seeing a lot of longevity from those pumps, provided they have a good fuel supply.
“As for the P7100 conversion as an option,” Alec says, “yes, it’s more reliable than the original VP44. But the conversion gets to be a pretty pricey build, because you need to find a core VP44 pump to build, along with modifying the injectors and getting a conversion kit. We see P7100 conversions costing upward of $5,000 to $6,000 when everything is added up.”

Hot Start Issue

The VP44 injection pump on my ’99 Dodge Ram with 142,000 miles failed. A local shop installed a rebuilt pump along with a new lift pump. After the installation, the engine would start instantly when cold but crank for several seconds before starting (not instantly like it did before the pump failed) when it was warmed up. I contacted the rebuilder and, after testing it, another injection pump was installed. I'm having the same problem with the second pump that I had with the first: delayed starting when the engine is warm. Can you tell me if this problem can be corrected? If not, is the performance of my engine affected in any way?
Jim Paul
via email
There are several possible causes for 5.9L 12-valve Cummins engine starting problems. Oregon Fuel Injection’s website is a great source for solving issues like this one. The site has a neat area called “diesel diagnostics,” which has a section that deals with this particular concern—Dodge Diesel Diagnostics item #98 (https://oregonfuelinjection.com/services-repair/diesel-diagnostics-repair/dodge-diesel-diagnostics/#98):
HARD START: HOT OR COLD
1. Follow the same guidelines as no start.
2. Internal leaks at injector feed tubes, internal or external?
3. If supply (lift) pump recently failed, it could cause injection pump problems due to cavitation damage.
4. If the vehicle is a ’98 to ’00 there may be an ECM reflash (for hard-start), refer to TSB 18-015-00. This problem can show up at any time or mile range, but usually after the supply pump is replaced.
5. Faulty Overflow Valve, injection pump return.
Oregon Fuel Injection’s Mark Gotchall leans toward item #4 being the answer—the ECM needing a reflash. “We have a rig come in at least once a month with this issue and do the reflash, which cures the hard-start-hot problem. The TSB alludes to the idea that it is for arctic fuels, but if read closely it pertains to all hard-start-hot issues. The reflash tells the ECM/pump to deliver more fuel during hot cranking.”

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