Subscribe to the Free
Newsletter

Diesel Tech Questions

Top Tech

Bruce W. Smith
Oct 5, 2017
Photographers: Bruce W. Smith

VVT Turbo Cleaning

I hope you guys can help me. The exhaust brake on my 6.7L Cummins-powered ’08 Ram 3500 stopped working when I was hauling horses, and a check-engine light came on. That’s when I also noticed the turbocharger wasn’t making low-end boost. This is the diagnostic trouble code that appears: P2563. These problems are troublesome to say the least. The odometer shows 220,000 miles, and the engine is serviced according to the owner’s manual. The only modification is an Edge Evolution CTS programmer, because it has great gauges, and I can dial up more power when I’m towing. Everything else is stock.
Graham Hillstrom
via the Internet
A P2563 DTC indicates the engine control module has detected a problem with the variable-geometry turbocharger control. Either the electronic boost sensor has failed or the vanes inside the turbo are sticking in the wrong position. The most likely cause of both the exhaust brake not working and lack of boost on the low-end stem from the variable-vane actuators inside the turbo being clogged with carbon deposits (soot). When the actuators stick or lock in one position, it affects boost and exhaust braking.
The turbo can be cleaned by using a Cummins Engine Update Kit (PN 10128-UPD) to inject three cans of Mopar Diesel Turbocharger Cleaner (PN 68044565AA), a special water-based solvent, into the cleaning port (if so equipped) and following the detailed procedure noted in Service Bulletin 11-001-08. It’s a tedious, four-hour task that should be performed by a dealership or qualified diesel technician. The TSB also explains in detail how to modify the turbo if it doesn’t already have a cleaning port installed.
Once the cleaning has been completed, the TSB suggests referring to Service Bulletins 11-002-08 and 11-002-07 for detailed turbocharger, engine, and exhaust after-treatment system repair procedures. When cleaning (or replacing) a turbocharger, a complete repair includes thoroughly cleaning and/or inspecting several other engine and exhaust-after-treatment components. The systems must be cleaned so they operate as if they are in “like-new” condition. Do not omit a component or step in the cleaning process.
The turbo can also be removed, disassembled, and cleaned by hand, which is a tedious task that requires a lot of attention to detail and extreme care. Both cleaning methods are only as good as the person doing the work. A sure fix is turbo replacement, according to Alec Hembury at Industrial Injection Diesel Performance.“Cleaning is just a bandage fix. Replacing the turbocharger is the best guarantee that it will deliver like-new performance,” Alec says.

Gear Swap for Big Tires

I’m getting ready to have a 6-inch lift and 37-inch tires put on my ’12 Ford F-350. It’s my daily driver and tow rig that pulls a 14,000-pound toy hauler. What do you recommend is the best axle ratio? It currently has 285/65R18 BFGoodrich T/A KO2 tires and 3.55 gears with rear limited slip. It will have 37x12 50R18 Nitto Ridge Grapplers. I want to use Yukon Gear and Axle HP 4.30 gears, as I’ve heard good things about them. Before I take my truck to our local 4x4 shop, what else should I have them check out and what is a reasonable price for a gear swap? I just want to make sure they are treating me right and that the truck’s performance will be as good as it can be when I have to cross the mountains with the trailer.
Scott Edwards
via email
Photo 2/6   |   Gearing down one ratio for every 2 inches of tire height is a general rule of thumb to maintain a truck’s acceleration and towing performance. For example, switching from 33-inch tires to 37s requires changing a 3.55 gear ratio to 4.10. Online calculators provide exact tire-size-to-axle-ratio numbers.
There are several things you need to have checked out when putting a lift and taller tires under any 4x4. Re-gearing is mandatory if you want the truck’s performance to remain the same, and figuring out which gear ratio is needed only requires basic math: New Tire Diameter/Old Tire Diameter x Old Axle Ratio = New Axle Ratio. But if you don’t want to stress brain cells doing the calculation, there are several good online sources out there that make finding the “right” gear ratio as easy as inputting three numbers and letting the software do the rest. We like using the chart found at 4wheelparts.com because it’s easy to see the effect multiple axle ratios have on engine rpm, while the calculator at 4lo.com lets you plug in exact tire size to get a specific ratio.
In your case, the Nittos you want to run are 36.77 inches in diameter, while the stock tires on your Super Duty are 32.64 inches, and the current axle ratio is 3.55. When the math is done, the new axle ratio comes out to 3.99, which doesn’t exist in normal circles: The common axle ratios are 3.73 or 4.11. So you have the option of running 3.73s with an engine rpm close to 2,200 at 65 mph in Drive (1:1), or 4.11s and an engine rpm around 2,400. (Your engine should be turning about 2,350 rpm at 65 mph when the transmission is in Drive with the stock setup.)
Photo 3/6   |   Top Tech Regearing For Bigger Tires Ring Gear Bench
Our suggestion in this instance, when trailer towing is involved, is to err on the side of better acceleration and load-pulling torque with the lower-ratio 4.11s, which is one of the axle-ratio options Ford offers. Such a small increase in rpm shouldn’t have any noticeable effect on fuel economy.
Other things to make note of when you have the lift and taller tires slipped under your truck is making sure the installation shop pays close attention to the rear driveshaft and U-joint angles. Most shops that specialize in lift kits do this already. But we think it would also would be worthwhile to give the guys at Tom Wood’s Custom Drive Shafts (4xshaft.com) a call for their input as well. You’re investing a lot of money on the suspension and re-gearing, so making sure there are no driveline issues is good insurance that all your money has been well spent.
Prices for gear swaps can vary a lot depending on the quality of the gears and shop rates. A reasonable price for a Yukon Gear swap package and labor would be around $2,800. Throw in another $800 to $1,100 to upgrade from the limited-slip to a mechanical Grizzly Locker or ARB Air Locker in the rear.

Sputtering Ram

My ’99 Dodge Ram 2500’s 5.9L Cummins engine started hesitating at 40 to 45 mph while pulling a trailer, and now it’s starting to do it at 30 to 35 mph. It does this with Overdrive on or off. If I am behind traffic or in a 40-mph speed zone, it hesitates. The truck has 153,000 miles and is stock except for a fuel pump (now in-tank not on the side of engine). I had the VP44 injection pump replaced at 123,000 miles. A local shop thinks I need another VP44, but they didn’t put the truck on the computer to reach this diagnosis. If my problem is injection pump, what do you recommend? I hate to think it is the injection pump with only 30,000 miles. I am not mechanically inclined but hope it is a faulty sensor, solenoids, or bad cable connection. Thank you for any suggestions!
Ronnie Jones
via email
Photo 4/6   |   The Cummins VP44 injection pump is very reliable as long as it’s given a 12- to 16-psi supply of clean fuel. Cummins injection experts warn that fuel pressures of less than 8 psi are a fast track to premature pump failure.
Scan. Scan. Scan. Having an experienced diesel technician perform an electronic diagnostics test is always money well spent. Diagnostic trouble codes (DTCs) are the road maps to most engine-related problems. You’ve probably already double-checked your fuel filters and made sure there’s a good supply of diesel getting to the pump. But if it isn’t, make sure the fuel-supply pressure to the VP44 is 12 to 16 psi. “Anything less than 8 psi of fuel pressure and the VP44 is going to fail,” warns Alec Hembury at Industrial Injection Diesel Performance in Salt Lake City, Utah. Alec also recommends having the applied pressure sensor (APPS) voltage checked to see if it’s losing signal or not reaching the correct voltage. The APPS is the equivalent of the throttle-position sensor, so electrical problems there can result in erratic throttle responses.
Casey Castle at Dunks Performance says in-tank pumps are also weak links in a fuel system. “Check pressure and flow out of the lift pump. Check the filter for water or debris to make sure you have clean fuel,” he says. “Another trick is to re-torque the transfer tubes on the injectors. If one is loose, the fuel system will have a hard time making full pressure, and a leak can go undetected because they leak into the fuel return passage of the head.”
Our friends at Oregon Fuel Injection say the problem could also be transmission-related. Erratic torque-converter clutch operation in the lower speeds on ’98 and early ’99 automatics is the topic of TSB 18-02-99, which advises an ECM reflash that sometimes resolves the issue. The torque converter of that era locks up at 35 mph and slips into Overdrive around 45 mph. Mark Gotchall says, “Erratic APPS signal can sometimes be resolved (instead of a reflash) with the BD Diesel Performance 1300030 noise isolator. Monitor the scan tool for torque converter lock/unlock; if it is erratic, install the noise isolator. This problem normally will not set an APPS code; if you have a code, you may have a faulty sensor or wiring issue.”

No Automatic Hubs

I have an issue with the front hubs of my ’09 Ford F-350. When I turn the four-wheel-drive shift knob, the transfer case engages right away, but the hubs no longer lock by themselves. I have to get out of the truck and manually twist the hubs into the “Lock” position. When they are turned to the “Auto” position, nothing happens. Do I need to have the hubs replaced, or am I missing something simple here?
Steven Cotton
via the Internet
This is a relatively common issue with vacuum-operated locking hubs. Somewhere between the vacuum pump, the actuating solenoid on the passenger-side inner fender, and the steering knuckles, there’s a problem supplying the momentary amount of vacuum needed to engage/disengage the hub’s locking mechanism.
The hubs operate a lot like the way a ballpoint pen does: When your thumb presses down on the button on the pen, it snaps the ballpoint into position to write, and when you press the button again, the point retracts. Vacuum-operated hubs work in much the same manner, only instead of a thumb pressing a button, when you switch to four-wheel drive a 30- to 40-second pulse of vacuum—all controlled by the fender-mounted solenoid—locks the hubs. When you turn the selector back to two-wheel drive, a 15- to 20-second pulse of vacuum unlocks them.
“Rent or borrow a vacuum pump and check to see if the solenoid pulls vacuum on the lines that run to the front axle,” says Dunks Performance technician Casey Castle. “If it does, then carefully check the vacuum hoses for cracks or other signs of damage. If the solenoid and lines are OK, then the problem could be that one of the hubs is stuck, a wheel knuckle is bad, or a hub seal isn’t holding vacuum. It's a special seal that takes a special OTC installing tool (PN OTC 6697).”
Of course, you could always bypass the vacuum hubs and go the full-manual route with a set of Warn premium hubs.

Disjointed

QUESTION: My ’05 Chevrolet Silverado has a 6-inch lift with 5-inch blocks under the stock rear springs and all new parts up front. The suspension has been under the truck since 2011. Early on, I was replacing U-joints twice a year, then I switched to Spicer U-joints, which cured those ills. Or so I thought. I had an incident where I had to slam on the brakes because someone cut me off, and “bang!” the driveshaft flew out. As the shaft exited the truck, it cracked the transfer and transmission cases, broke the rear differential yoke, and chewed up output-shaft splines. I am looking at a $4,700 bill to get the truck back on the road, providing the insides of the transmission and transfer case aren’t damaged.
Technicians at my local 4x4 shop think a rear U-joint failed due to extreme driveshaft angle or binding. They say the best solution is to lower the truck. I talked with other shops outside my area that have worked on other Silverados with 6-inch (and higher) lift kits, and they say they have never had U-joint problems.
I thought maybe the rear springs or something else back there were loose or maybe there was axlewrap when the rear brakes locked up. I don't sled pull, drag race, or use the truck off-road. But I do tow a large travel trailer often and enjoy the extra torque and fuel mileage of the truck’s 6.6L Duramax engine. I love the truck but can't afford another major repair.
John Leccardello
via email
Photo 5/6   |   Thrown driveshafts on lifted trucks are usually the result of improper geometry, coupled with not stepping up to a larger-diameter, correct-length shaft. The driveshaft shown here is too short, as evidenced by the wear pattern (arrows) of the output-shaft seal on the slip yoke. Lift blocks and excessive axlewrap can also contribute to dropping a driveshaft.
A failed U-joint could be the culprit that let everything fly, but don’t discount several other factors that may have possibly contributed to your expensive and unfortunate mishap. Tom Wood, owner of Tom Wood’s Custom Drive Shafts (4xshaft.com), always stresses that the driveshaft geometry is critical to trouble-free performance in lifted rigs, and owners should carefully measure those angles because U-joints are designed to operate within a finite range of degrees or else they’ll prematurely fail. (By the way, replacing rear U-joints twice a year is a sign that something is amiss in your truck’s driveshaft geometry.) Check out TWDC’s website and take a very close look at the “Tech Info” section regarding driveline geometry, slopes, and angles.
Tom was able to point out several things from the images of the failed driveshaft and U-joint that you provided. His keen eye caught the following: damage to the journal on the universal joint that could be related to some deformities on the attaching pinion yoke in the half-round cutout where the bearing-cap seats. “When this happens, the bearing cap will misalign,” Tom says. “This prevents an even load distribution across the needle bearings and will cause a failure every time.”
Tom says a simple test to see if a damaged attaching yoke might be the underlying cause of the failure is to get a new universal joint and attach it directly to the pinion yoke. Install the U-joint with the proper torque, then rock the universal joint back and forth between your thumb and forefinger. There will be some resistance. But if it feels rough at all, the old pinion yoke should be changed.
Tom also pointed out your truck’s driveshaft appears to be significantly too short. The photo you sent clearly shows where the seal on the output of the transfer case has been riding on the last 2 inches of slip yoke (orange arrow). Generally speaking, the seal should ride within an inch or two from the U-joint end (green arrow). When the driveshaft rides that far down the slip yoke, axlewrap under severe braking can cause the separation you experienced.
Then there’s the driveshaft itself. Tom says the 3-inch-diameter driveshaft “looks like it is a bit small” for the length that’s required for a 6-inch lift. “It may be that the driveshaft is running near or beyond critical speed. When this happens, the tubing flexes. The faster the driveshaft spins, the more it flexes. At some point, it will whip out of the vehicle (that’s why it’s called ‘critical speed’). If I were to build this driveshaft, I would use nothing less than a 3.5-inch-diameter tube.”
Tom suggests a resolution to the problem is the following:
1. Replace the pinion yoke (when in doubt, throw it out)
2. Install a double-cardan driveshaft, rotating the differential upward so the pinion points directly at the output of the transfer case while maintaining 3 degrees or less of joint angle at the differential end. For example, if the slope of the driveshaft is 15 degrees, the pinion angle should be between 12 and 15 degrees, with 13 to 14 being ideal.
Turning to the springs, Dunks Performance’s shop foreman and suspension technician Casey Castle says they constantly battle soft rear springs in lifted GM pickups, with symptoms ranging from spring “slap” while braking or under acceleration to driveline vibrations under load. “The way we resolve those issues if the driveshaft angles are within specification is by installing a set of traction bars like those from Epiq Suspension (epiqsuspension.com) or replacing the stock leaf springs and lift blocks with the appropriate progressive-rate leaf springs such as those offered by Deaver Suspension.”
The typical issue that arises with lift blocks is they amplify the torsional pressure placed on the factory rear springs, causing them to wrap under severe braking, accelerating hard when towing a heavy trailer, or trying to power through sand. Progressive-rate, high-arch spring packs eliminate the need for lift blocks. “When the leaf-spring pack is placed directly on the axle and not leveraged on top of a lift block, it can then control the torque the axle is subjected to, eliminating any wrap-up during takeoff or under hard braking,” explains Deaver Suspension’s Scott Born.
Traction bars, which usually cost a little less than custom leaf springs, will also eliminate axlewrap. If they are designed correctly, they will not restrict vertical suspension movement in the conditions under which you use your rig. They are also easy to install. First, make sure the driveshaft angles and slopes are correct, and the proper driveshaft is being used. Then consider installing traction bars on your current setup or ditch the factory springs and lift blocks for leaf-spring packs designed to maintain your truck’s lift.

Hard Start on Slope

I’m having a cold-start issue with my ’04 Ford Excursion’s 6.0L Power Stroke engine. It starts and runs fine when the truck is parked on a level surface or when the front end is low. But when it’s parked with the nose higher than the rear, like on my driveway, the engine cranks for half a minute or more before it fires up. Otherwise, it runs fine. Any suggestions as to why this is happening? The Excursion has 168,000 miles on it, and it’s serviced regularly.
Vern Lindly
via the Internet
Photo 6/6   |   Hard-starting Ford 6.0L Ford Power Stroke engines in trucks that have been parked with the nose higher than the tailgate usually draw the attention of diesel technicians to the high-pressure oil pump located at the back of the valley. Leaking seals or a bad injector-pressure regulator are the usual suspects that cause the problem.
ANSWER: Our first thought is something is amiss with the engine’s high-pressure oil pump (HPOP). We contacted Anthony Youngblood at Super Duty Service to get his thoughts about the concern, and sure enough, he’s seen this many times during a decade of specializing in 6.0L Fords. He says there are typically three HPOP-related scenarios that cause hard starts when the truck is parked on slopes: 1) The pump itself is leaking and draining the reservoir, 2) the shaft seal is leaking, or 3) the seal under the pump is leaking. “Either way, when an engine takes a while to start after being parked nose-high, it’s a symptom that points toward getting down to the pump and checking it out,” Anthony says.
Technicians monitor the injector-pressure-regulator (IPR) percentage, which controls the rate at which the high-pressure oil reaches the injectors to see if it shows 84 percent while cranking—and/or during a wide-open-throttle acceleration with stock ECM calibration. This also points toward an HPOP issue.
“A reading of 84 percent means the IPR valve is not bypassing any oil and pumping it straight into the HPOP’s closed-loop system,” Anthony explains. “The HPOP pumps full bore at all times the crankshaft is rotating, then the IPR valve routes the oil to the system or back to the sump.” Also, making sure the oil filter is soaked in oil directly after removal will rule out other potential issues.

POPULAR TRUCKS

Subscribe Today and Save up to 83%!

Subscribe Truck Trend Magazine

Subscribe to:

Truck Trend
Magazine

PRINT DIGITAL
Subscribe Diesel Power Magazine

Subscribe to:

Diesel Power
Magazine

PRINT DIGITAL
Subscribe Truckin Magazine

Subscribe to:

Truckin
Magazine

PRINT DIGITAL
SUBSCRIBE TO A MAGAZINE
CLOSE X
BUYER'S GUIDE
SEE THE ALL NEW
NEWS, REVIEWS & SPECS