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Top Tech - Diesel Tech Questions

You've Got Questions? We've Got Answers!

Bruce W. Smith
Mar 2, 2016
Photographers: Bruce W. Smith
Super Duty Transmission Slip
My ’06 Ford F-250’s automatic transmission feels like it’s popping out of gear during hard acceleration or from a hard launch. It’s been doing this for several years. The truck has 79,000 miles, 37-inch tires, and 4.88 gears, and it’s mildly upgraded with a Powermax turbo and Innovative Diesel tunes. If I get on the freeway and have the pedal to the floor, somewhere around Fourth gear the engine revs out. I can usually just let off the pedal and coast for a bit, and then the transmission works properly again. It doesn’t happen during normal driving, or when towing my 35-foot toy hauler. I had a new ATS Diesel Performance transmission installed along with its billet flexplate and ATS Five-Star converter thinking the stock transmission was going out and causing my problems. The problem still exists.
Stan Leeman
via the Internet
When the new transmission was installed, did anyone check the wiring harness? Mike Meinecke at ATS Diesel Performance (ATSdiesel.com; [800] 949-6002) says those symptoms sound more like your truck has a bad external wiring harness than a hardware issue. “We have seen a few F-250 wiring harnesses that have rubbed against something coming down from the computer or rubbed through in the loom itself. That transmission has a few different 12-volt power wires coming down to it that activate certain solenoids. If one of those solenoids loses its power, or a ground signal from the computer to the transmission is lost, even for a moment, it can create a ‘neutral’ condition because the solenoid shuts off.”
Check the wiring closely. The fix to your ongoing problem could be just a few wraps of electrical tape away.
Photo 2/4   |   002 Top Tech Warped Heads
Machine shops around the country are paying special attention to out-of-the-box Ford 6.0Ls heads, resurfacing them to ensure the decks are within factory specs.
Warped New Heads
Last fall, I rebuilt my ’06 Ford F350’s 6.0L engine after the oil cooler failed, resulting in a blown head gasket and cracked cylinder head. I put in ARP studs, upgraded the EGR and oil cooler, had the engine block checked and cleaned up, and put on new factory-replacement heads. Now it appears to have blown another head gasket. Everything was done to spec, and I thought I did a great rebuild. Where did I go wrong—other than sticking with the six-oh?
Les Miles
via email
It’s tough to pinpoint why any rebuild goes south. But, according to several experts of Ford 6.0L rebuilds, you may have overlooked one critical area: warped head assemblies.
While Ford says “do not” resurface 6.0L heads, most of the well-equipped and knowledgeable machine shops we talked to about this are resurfacing those heads every day—even castings that are taken right out of the box. Given the 6.0L’s 15-bolt cylinder heads, keeping very tight tolerances across their surfaces is critical to proper head gasket seating. When the heads are not perfectly secured, head gaskets fail.
Machinists at Southworth Inc. ([541] 431-0556) in Eugene, Oregon, say they have seen a number of out-of-the-box, factory-remanufactured 6.0L heads come through their engine shop that measure .005- to .008-inch out of spec across the fire deck, requiring resurfacing.
Anthony Youngblood at Super Duty Service (sdutys.com; [816] 548-6970) in Grain Valley, Missouri, says his 6.0L specialty shop “never installs OEM Ford remanufactured heads without resurfacing them first.”
Photo 3/4   |   004 Top Tech Cold Blooded
Hard-starting during cold weather conditions could be a sign of bad injectors and not a failure of glow plugs or the fuel heater.
Cold-Blooded in Indiana
I have a late-’99 Ford F-250 that is a bit troublesome to start in cold temperatures. I replaced the glow plugs with hotter Wellman units and installed a new relay in 2013. Everything tests fine with a multimeter, but the engine is still hard to start. Would connecting the air intake heater relay to the glow plug relay help cold starts? The 12-valve Cummins in my ’97 Dodge Ram starts easier at lower ambient-air temps with its grid heater, which is why I'm considering trying this idea.
Chad Johnston
via email
If the 7.3L’s glow plug system is operating properly, your truck’s seemingly cold-blooded engine might have an injector issue. Shawn Smalley at Mobile Diesel Service in Oakland, Oregon, has seen this type of engine-start behavior before and recommends running a compression test and sending the injectors off for testing.
Shopping Pricey Injectors I have a ’95 Ford F-250 with 280,000 miles that has all the symptoms of bad injector O-rings. I considered trying to replace them myself, then I figured it’s best to just bite the bullet and replace the injectors. My concern is that this is a big investment and I'm not sure where to get the injectors. There seems to be quite a difference in prices for rebuilt injectors. Is there a reason the prices vary so much? Curt Williams via the Internet
Replacing injectors is one of those areas where the cost and time involved requires doing everything right the first time around. Tolerances on injectors to operate correctly are very tight, and with 280,000 miles on your truck’s odometer, this is replacement time. But don’t go bargain-hunting in the process.
Mark Gotchall at Oregon Fuel Injection ( oregonfuelinjection.com; [541] 485-1434) warns that big price differences in injectors usually reflects quality of product: “A lot of the less expensive injectors don't get the nozzles or nozzle springs replaced in them, which are common failure items and will affect fuel delivery. Some of the less expensive injectors also have wide variations in the armature settings, which will affect their timing.”
In short, higher-priced rebuilt or exchange injectors usually reflect better quality that results in improved performance and reliability. On the upside, Mark recommends “AD” code injectors, used in the ’99½-to-’03 7.3Ls, be replaced with new ones because of the wear in the bodies at the poppet-valve seat. Mark also says that for the older “AA” or “AB” code injectors, rebuilt units will be just fine.
Regen Rejection Woes
My ’08 MegaCab Ram 2500’s 6.7L Cummins engine is stuck in “power-reduced” mode after the diesel particulate filter (DPF) system wouldn’t perform its regenerative-burn cycle. The “Exhaust Filter Full. 80%” message came on while making a trip to town, so I continued to drive for another 15 minutes on the highway, hoping it would regen. It didn’t. Now a warning reads: “Exhaust filter full. See dealer. Power reduced.” This has happened before, and I’m tired of paying the dealer to force the regen to work right and clear the code(s). Is there anything I can do to get the regen to work the way it should? My last resort is deleting the emissions crap, but I’m hoping there’s a less costly solution.
Karl Haas
Arlington, Texas
It sure would be nice if we could just pop open the DPF and shake it out like an air filter. Unfortunately, it’s a lot more complicated process to flood it with fuel for the regenerative burn-off.
Frequent DPF clogging (accompanied by the warning lighting up) is often the result of not giving the system enough time to do a complete regen. Ram engineers told us regen typically takes 20 to 30 minutes of driving at 50 to 55 mph to complete when a filter is at that stage.
If the DPF doesn’t regen in 30 minutes, other possibilities could be the filter itself is bad, or something in the emissions’ computer-controlled system is askew, which means a trip to the dealer. Take it in and have a technician force the regen and check the system.
After the DPF is clean, Xtreme Diesel Performance’s experts (xdp.com; [732] 719-0955) suggest trying a performance tuner, such as the Bully Dog GT, which offers the Mobile Desoot (diesel particulate filter burn-off enable) as well as the Initiate DPF Burn-off feature. That way you can activate the regen whenever you want.
Photo 4/4   |   003 Top Tech Trailer Toter
There are a number of ideal heavy-duty rigs that can be used for commercial RV trailer towing. A dualie and its additional cabin space make those cross-country tows a lot easier on the driver and co-driver.
The Perfect RV Trailer Toter
I’m interested in towing RV trailers commercially from Elkhart, Indiana, to the lower 48 states. My research shows the most dependable, reliable, and efficient truck for this application would be a 5.9L Cummins-powered ’05-to-’07 Dodge Ram 3500 with a six-speed manual transmission and 3.73 rearend gears. Due to the age, mileage, small selection, and overpricing of these trucks, could you recommend a second or third choice?
Chad Troxler
via email
Those older Dodge Ram 3500s with the 24-valve Cummins engine and manual transmission are great work trucks that most owners don’t like parting with, which is why they are in short supply and command a premium price.
For commercial RV trailer towing, we suggest looking closely at one of the newer-generation Rams, possibly a Quad Cab dualie because of the wide range of tow-behind, gooseneck, and fifth-wheel trailers it can handle, as well as the driver comfort the setup provides over long hauls. And if you’re delivering trailers around the country, you’ll want to be comfortable! We prefer automatics over manual gearboxes because they require less maintenance over the long haul.
If you are not bound by brand, you might consider an ’07-to-’09 Chevrolet or GMC dualie. The 365hp, 660-lb-ft 6.6L Duramax LMM is strong. So, too, are the more powerful ’10 models with the LML version of the engine, which includes a built-in exhaust brake.
Ford’s F-450 Super Duties (’08 to ’14) with the twin-turbocharged 6.4L Power Stroke engine would also be ideal for handling the heaviest of commercial RV towing duties, offering both automatic and manual transmissions in the combination you have in mind.
For best prices and availability of all the above, check out states with high numbers of horse owners, because they typically put low miles on their trucks and keep them in very good condition.

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