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High Performance Diesel Engines

By Bruce Mallinson, Andrew Wilson, Ethan Fortuna

February, 2019

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If you’ve listened to our radio show, the Pittsburgh Power Hour on Road Dog Trucking Sirius/XM Ch. 146, you would know how difficult it can be to diagnose a problem over the phone. Recently we had a customer call who’s 2007 Detroit DDEC V equipped car hauler was experiencing a loss in power and fuel mileage. The truck was struggling on the hills and returning an abysmal 4.3 MPG. The owner-operator was keen enough to have a boost gauge installed and noticed the VG turbo was running at 30 pounds of boost on level ground at 65 MPH. Obviously there is a serious issue here because it should be at 8-10 pounds of boost, but what could it be? Our lead Engineer Ethan said he has seen this happen twice. Once was caused from a bad tuning program. On that truck, the tune was causing the ECM to put the truck in high altitude mode and running a high level of boost at all times. It could also be an assortment of mechanical issues. Most likely it’s the turbo or a bad boost sensor, but it could be caused by almost any other mechanical issue making the truck to run poorly. Another possible cause is it could be the variable vanes in the turbo not opening completely due to exhaust soot (our Diesel Force engine cleaning system will eliminate that problem). Diagnosing a problem like this can be like solving a large jigsaw puzzle. There are many small pieces and they all have to fit together to give you the whole picture. In this case, there are not enough pieces of information to give a proper diagnosis. That is why we often suggest owner-operators bring their trucks to the shop because there are only so many tests we can give you over the phone to determine the cause of the problem. The average person may not have the tools to diagnose it themselves. We welcome people to call us with your complicated issues because that’s our specialty, however many of these problems must be repaired at our shop.

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Fans of our social media accounts, Facebook, Instagram, and Twitter know that every week we post pictures of a spectacular mechanical failure known as the “Fail of the Week.” Every week we see new ways these trucks are failing. We like to share it with everyone, hopefully helping you all avoid the same mistakes that lead to those failures. This week’s fail of the week was a Detroit ECM that was sent in to us. It looked like a typical ECM on the outside, but on the inside, the circuit board was completely covered in a thick greasy sludge. We’ve seen this problem before, but not to this degree. The sludge was a mix of oil and fuel dripping off the engine right into the ECM. What happens is the seal on the ECM case breaks and allows debris inside. The customer was not aware this was the cause of the malfunction. Surprisingly, Ethan was able to clean the sludge of and repair the ECM. So during your routine mechanical checks, look at the ECM and make sure it’s staying as clean and dry as possible. 

One of my favorite subjects, TORSIONAL DAMPERS AND MERCURY FILLED ENGINE BALANCERS, and the ignorance that goes with them. I have been preaching about this part of the engine since my first article in 1989 and most of the mechanics are still ignorant of what these two parts do. The torsional damper on the front of the crankshaft absorbs torsional twisting of the crankshaft and camshaft. By eliminating the torsional twisting, the engine will pull more consistently and smoother, eliminate breakage of AC compressor brackets, alternator brackets, knocking springs out of clutch discs, eliminate the breaking of transmission input shafts, flywheel bolts, and flywheel housing bolts. This part does so much, and most mechanics say, “we never change this harmonic balancer.” They don’t even know the correct name of the part. About 2 months ago I had a phone call from an older owner operator with a 379 Pete powered by a DD4 Detroit and he heard a noise coming from the front of the engine which was just rebuilt by a Detroit shop 140,000 miles ago. This engine had over 1 million miles on the Bull Gear and the torsional damper and was NOT informed by the mechanic or shop foreman that the parts needed to be changed. As you can see by the picture the damper is old, rusted and original. These dampers are ONLY good for 500,000 miles or 10 years. The silicone in side that dampens the large steel ring that floats in the housing becomes hard and stops the movement of the absorption ring. Now something on the truck will become sacrificial and break and your body absorbs the vibrations right up through the seat, pedals, and steering wheel. The shifter will rattle, the door locks vibrate, and the mirrors and antennas will shake. Sometimes the mirrors shake so bad you can’t use them to back the rig up. That is how important this torsional damper is and 99.0 percent of shop foreman and mechanics don’t know about it. If the mechanic working on your engine says we never change the harmonic balancer, take your truck to another shop. The following stripped gears are the result of the faulty damper, as you can see how old the damper appears. If you’re a nickel squeezer and wont replace parts until it’s too late, the cost of repair is catastrophic. Being cheap with the piece of equipment that makes your living possible is a direct route to disaster.

Written by; Bruce Mallinson, Andrew Wilson, Ethan Fortuna

Pittsburgh Power Inc., 3600 S. Noah Dr. Saxonburg, Pa. 16056

Phone 724-360-4080

Website: Pittsburghpower.com