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Diesel Tech Questions

Top Tech

Bruce W. Smith
Jul 11, 2017
Photographers: Bruce W. Smith

O2 Sensors Dying

My question is about oxygen sensors. I own an ’09 Dodge Ram 3500 with 80,000 miles on the clock. I service the 6.7L Cummins engine every 3,000 miles, and it’s been trouble-free, with the exception of the O2 sensors. About 95 percent of the mileage was accumulated towing a 14,000-pound trailer, and my truck is worked on a regular basis. At approximately 30,000 miles, a check-engine light displayed, and a scan test revealed the O2 sensors are the problem. I replaced them with new, reputable O2 sensors, installed the exhaust blanket around the first sensor on the stock exhaust pipe, and cleared the codes. It ran flawlessly for another 25,000 to 30,000 miles, and then the problem repeated itself. This is the third set of O2 sensors I’ve replaced. I was told this is a rather common event with the 6.7L engine for the ’09 model year. Do you have any answer as to why the sensors last only 30,000 miles?
Pete J. Sparacio
Shingletown, California
Photo 2/6   |   Preventive maintenance and the use of diesel fuel additives that boost cetane can prolong the life of 6.7L Cummins O2 sensors. Excessive idling and poor fuel quality are significant contributors to coking of the sensors.
As always, we can’t stress enough how important it is to know the specific diagnostic trouble code that is triggered, as it helps us narrow down the potential problems. There are 11 codes related to the oxygen sensors, and each one leads down a specific path to a solution:
• P0031-Heated Oxygen Sensor (Bank 1 Sensor 1) Heater Circuit Low Voltage - Manual and Automatic Transmission
• P0037-Heated Oxygen Sensor (Bank 1 Sensor 1) Heater Circuit Low Voltage - Manual and Automatic Transmission
• P0131-Oxygen Sensor (Bank 1 Sensor 1) Circuit Low - Manual and Automatic Transmission
• P0135-Heated Oxygen Sensor (Bank 1 Sensor 1) Heater Performance - Manual and Automatic Transmission
• P0137-Heated Oxygen Sensor (Bank 1 Sensor 2) Circuit Low Voltage - Manual and Automatic Transmission
• P0141-Heated Oxygen Sensor (Bank 1 Sensor 2) Heater Performance - Manual and Automatic Transmission
• P113C-O2 Sensor Power Supply Performance - Manual and Automatic Transmission
• P2271-O2 Sensor (Bank 1 Sensor 2) Out-of-Range Low - Manual and Automatic Transmission
• P22AB-O2 Sensor (Bank 1 Sensor 2) Positive Current Control Circuit / Open - Manual and Automatic Transmission
• P2A00-O2 Sensor (Bank 1 Sensor 1) Circuit Performance - Manual and Automatic Transmission
• P2A01-O2 Sensor (Bank 1 Sensor 2) Signal Circuit Performance - Manual and Automatic Transmission
Mark Gotchall at Oregon Fuel Injection (a company that does a lot of diesel diagnostic work in the Pacific Northwest) says the most likely cause is carbon buildup. Normally, towing runs the exhaust hotter and will not allow carbon to build up. However, excess idling can cause oxygen sensor problems on DPF-equipped trucks. Excess idle time might be defined as leaving the engine running while hooking up a trailer or letting it warm up before heading down the road.
Mark also notes that poor-quality fuel may also be the root, because it increases carbon buildup and coking on the O2 sensors. We published an article on diesel fuel quality (“Cetane Numbers”) in our July ’17 issue, which details that subject. A regular dosing at every fill-up with a diesel performance formula fuel additive that incorporates a cetane booster would help reduce carbon buildup in the exhaust.
If changing operating/driving habits and using a fuel additive doesn't help, maybe removal and cleaning of the oxygen sensors at around 15,000 miles would prolong their life. This type of preventive maintenance isn’t fun, but it’s better than spending the money on new sensors like you’ve been doing.

Distant Thunder

Google is not my friend. Is there a compression brake for a 5.9L Cummins-powered ’07 Dodge Ram? There is an obscure “Thunderbrake” website out there, but nothing else is coming up. I am not a big “noise guy,” so don’t want an exhaust brake. I am very familiar with military compression and exhaust brakes. Compression works better.
Nick
via Facebook
Photo 3/6   |   Thunderbrake, a concept Jake-style compression brake for the 5.9L 12-valve Cummins engine found in light-duty Dodge Ram pickups, is still a “work in progress” and has not gone into actual production, according to its developer Wayne Newman.
We were curious, too, Nick. A few years ago, Thunderbrake made a pitch to find investors to back development of a true Jake-style engine brake for the early 5.9L Cummins. We contacted Wayne Newman, one of the two people trying to get the Thunderbrake into production, to see where the effort is today. Here’s his reply:
“Did we get funding? No. Have we continued to work on the project anyway? Yes. We are making our first round of ‘production’ parts for a 12- valve. We began with this engine because it is the simpler of the two, but we knew the real market would be for the 24-valve, so as soon as we had a proof-of-concept model for the 12-valve, we immediately started to work on the 24-valve.
“We bought an ’05 with a 48RE transmission so we could learn about locking the torque converter and learn how to make the computer shut off the fuel while braking. Once we had that under our belt, we went back to work on the 12-valve, focusing on packaging of components to make it a marketable product instead of just a science project. We work slowly because we have to ration our time and not get so caught up in the project that we starve to death.
“Right now, we're really not focused on trying to sell something we don't have yet. We are trying really hard to get parts made and get testing done, so that when the time comes we will be ready with a dependable product. Until then, here’s a photo of it in its current stage. Thanks, Wayne Newman.”

6.4L Blues

I bought an ’08 Ford F-350 with 131,000 miles on it. Seven months (and only 5,000 miles) later, the 6.4L Power Stroke engine locked up. It turns out, the number 7 and 8 cylinders are both destroyed, and I've yet to determine the exact cause. No one I've talked to will give me a straight answer about rebuilding it; everyone says replace it. I don't have $10,000 for a new engine, and I don't mean to sound stupid, but is it even worth trying to rebuild?
John Yarber
via email
Photo 4/6   |   Replacing a diesel engine is costly, but when it happens, the easiest way to handle the job is by lifting the body off the frame to make access to the engine easy. Most diesel shops can pop a Super Duty body off in about four hours, but that time is more than made up when compared to the aggravation of doing a complete rebuild with the body in place.
John, we hate to be the bearers of bad news, but the people you have talked with about this are right: With the kind of damage you mention, rebuilding the engine is not worth the expense. Pull the body off the frame, salvage what you can from the blown 6.4L to reuse on a remanufactured short-block, and move on. There are several suppliers out there offering short-blocks for those ’08-to-’10 Super Dutys, with prices anywhere from $4,000 to $7,000 (depending on what level of performance you seek). The bad news is you’ll probably have to pay the core charge, which runs about $1,500 to $1,800 on top of the price if you send your block back and they deem it junk. Typically, a rebuild like this would cost between $10,000 and $12,000.
Photo 5/6   |   An ’08 6.4L Power Stroke engine with this type of obvious external damage before even getting deep into the block is not good. Now, it’s decision time regarding how much of an investment the truck is worth—and that’s a hard question to answer for some owners when a repair bill could be $10,000.
Of course, if you decide to hold onto it, we suggest you have a long talk with a good Ford diesel mechanic about preventive maintenance: What caused the demise of the original engine and common weaknesses in the 6.4L? Knowing that information should help in both the rebuild process and maintaining the overall long-term reliability of your truck.

Hot-Blooded Sierra

I have an ’05 GMC Sierra 2500 HD with a 6.6L Duramax engine and Allison automatic transmission. During the winter, I started experiencing an overheating issue when I was using the snowplow. The truck had almost 200,000 miles on it when I had to tear down the top end of the engine due to bending a few pushrods. I had the heads checked, new valve seals and guides installed, and ARP head studs put in. While the engine was on the stand, I also replaced the water pump; added new thermostats; cleaned the cooling stacks; flushed the cooling system; added PPE exhaust manifolds, up-pipes, and a down tube; upgraded the turbocharger to an Industrial Injection Duramax upgrade Stage One; and loaded a PPEI program in the ECM. Since I’ve had the truck back on the road, it’s had an intermittent overheating issue when the snowplow is on. The truck has never had any temperature problems until now. I've replaced the thermostats again, as well as the cooling fan clutch, and it is still overheating when driving with the plow on. There’s no telltale smoke out of the exhaust or any abnormal coolant consumption. Do you have any suggestions or ideas before I end up tearing the engine down again and starting over?
Dave Prevost
via email
Before going back to the engine stand to recheck your rebuild work, consider looking at the cooling problem with fresh eyes. Our best guess is that when you put the engine back in, the air diverters and baffles around the radiator may have somehow been left loose so it isn’t getting max airflow. These become critical components when any diesel pickup is being worked hard—especially while moving slowly plowing snow. Even though the air temperatures are below freezing, the engine is generating a tremendous amount of heat in that environment, and there’s very little air being forced through the radiator by the truck’s movement to keep coolant levels within safe operating range.
If those components are in place, then there’s something on the plow that’s blocking air getting to the radiator.

Rollin’ Snow

I have an ’05 Chevrolet Silverado 2500 HD with a 6.6L Duramax LLY V-8 and an Allison automatic transmission. The LLY engine expired at 138,000 miles with two spun rod bearings because the oil pump failed. I replaced it with a crate LMM long-block from Banks Power. All the original LLY fuel-system components, as well as the turbocharger and water pump, were swapped onto the LMM. The only modification for the swap was to grind a specific tooth off the LMM’s reluctor wheel. The new engine starts, idles, and drives perfectly until I roll hard into it at more than 70 mph. When trying to pass at those higher speeds, during the transmission downshift, the engine loses power and blows white smoke out of the exhaust pipe. Once the accelerator pedal is released, everything seems to return to normal. Any idea what is happening? Could it be EGR cooler or computer module problems?
Sammy K. McLain
via email
Photo 6/6   |   Chevrolet and GMC diesel pickups plowing snow need maximum airflow through the radiator to maintain safe operating temperatures. Any blockages or damage to the air deflectors that force moving air through the radiator instead of around it can cause overheating.
Our suggestions: Don’t drive faster than the posted speed limit, and, if you must pass someone, only do so at speeds less than 70 mph. Problem solved.
Now that we’ve busted your chops, it sounds like it’s either 1) a bad injector, 2) a head gasket on its way to failing, or 3) a rail-pressure issue. First, scan the OBD II system for diagnostic trouble codes. Alec Hembury at Industrial Injection says they scan for “actual” versus desired rail pressure during a hard pull at highway speed to see if that’s the cause. He says they’ve seen CP3 injection pumps not keeping up or the pressure-relief valve open up on a long pull, which will cause rollin’ snow. Finally, pressure-test the cooling system to determine where a possible leak is located. If it’s losing coolant, the finger points at either a hose failure or a head-gasket issue. If there’s no sign of coolant loss, have your dealer or someone with a technician’s scan tool perform a “cut-out test” of the injectors. Normally, white smoke is an indication of water getting into the exhaust. However, a bad injector will create the same condition. White smoke under hard acceleration is caused when a bad injector dribbles unburned fuel into the exhaust.
Just a note: LMM injectors, like most, need support in the form of a good lift pump, water-free fuel, and good lubrication for a long, trouble-free life. A high-quality diesel additive that increases lubricity, a top-notch fuel filter system, and a strong lift pump provide those three elements.

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