High Performance Diesel Engines

Bruce Mallinson
May 2017

Be careful with the DEF (Urea) tank on your 2011 semi-truck or pickup truck, It’s not compatible with diesel fuel. Never install or allow anyone to put diesel fuel into the DEF tank. If this happens and diesel fuel gets into your DEF tank the urea will turn into a wax, like ear wax, yes, the wax that your body produces in your ear canal. What a disaster this is to the emissions system and the following is a list of what we had to do to correct this problem.

#1 Remove the DEF tank and clean out all the wax material.

#2 Replace the heating and urea pick up assembly.

#3 Flush the lines, which are heated, to the doser valve.

#4 Replace the doser valve and the electric pump.

#5 Force a re-gen, dyno test and a long test-drive to make sure the emissions system works properly.

Hot soapy water does NOT remove the wax material, on petroleum-based solvents.

DD15 Detroit engines; we have been doing a lot of work with this new design Detroit engine and it’s been a very good engine for owner-operators. We currently have one in the shop with excessive coolant leaks on the exhaust side of the engine, the right or passenger side, also an oil leak on the right rear rocker box housing. The coolant leaks are a result of the gasket that seals the water manifold to the head, which is right behind the exhaust manifold. Now what I find strange is having an aluminum water manifold within ¼ inch of the exhaust manifold. The old rule in engine building is aluminum expands and contracts much faster than cast iron and should only be used as covers. Exhaust manifolds can get cherry red pulling a mountain, so there is a lot of heat being generated and soaking into the water manifold. The water manifold also holds the EGR cooler, which is stainless steel. The picture of the water manifold gaskets clearly shows the failure causing the coolant leaks. This is a major repair, especially being the rocker assembly housing is cracked and must be replaced. Something else I see that has me concerned is there are NO cam bearings in the aluminum rocker assembly. Detroit considers this rocker housing to be a wear item, however it’s $1600.00. Now with no cam bearings and a 50,000-mile oil change, there is visible wear on the cam journal, enough that we now have to replace the cams because a new rocker assembly is being installed. The estimate on this repair is 33 hours, and that is according to an SRT manual. SRT stands for Standard Repair Time, which is usually low because the engines the OEM’s use is new to establish these times. No dirt, rust or broken bolts. This engine also has new style camshafts, which are hollow, not a bad thing; very light weight, however the lobes are NOT machined into a steel billet.

John Walko, our mechanical engineer likes this engine, so I will let him explain the great features to you.

There are numerous things that I like a about the DD15; it is a truly modern low friction high efficiency engine. The camshafts are of a modular design meaning that the lobes are ground separately from the shaft, the lobes are then fixtured to the hollow shaft and the shaft is expanded with hydraulic pressure to create an interference fit between the lobes and the shaft. The result is a durable part that has about half of the rotating mass of a conventional camshaft. The gear train that drives the cams is comprised of gears that are about half the width, half the weight and look like a clock maker made them. The benefits here are twofold, less friction due to less surface area on each gear tooth and again less rotating mass. Keep in mind that it takes fuel to make everything go around, low friction piston and ring assemblies and variable speed water pump also increase efficiency. I have yet to see the bottom end of one of these things apart (that’s probably a good thing), but I’m sure that I will find more cool stuff there. Factory tuning has this engine making peak torque at 975 RPM, which I find amazing. I believe that as we get to diminishing returns with combustion efficiency down speeding will be the next frontier and Detroit seems to on to this. These engines also respond quite well to our tuning and benefit greatly from our Soot Separator EGR filtration system. What’s not to like?

Written by: Bruce Mallinson, Pittsburgh Power Inc., 3600 South Noah Dr. Saxonburg, Pa. 16056 Phone 724-360-4080 Website: www.Pittsburghpower.com