High Performance Diesel Engines

Bruce Mallinson, Leroy Pershing, and Jordan Greathouse
January 2024

Did I hear someone say a Volvo with a Volvo engine never breaks down? Well, guess what? We have a Volvo powered by Volvo in our shop for vibration issues. Our team of electrical engineers installed our vibration-analyzing equipment on the truck while it was running on the dyno and found severe vibrations coming from the front of the truck. Upon inspection, they found the four front engine mount bolts were gone. Nothing was holding down the front of this engine; I'm surprised the engine is still in the chassis. If this had been a mechanical engine with throttle linkage, the driver would have known something was wrong because as the engine torqued up, the linkage would have been pulled, and the engine would have accelerated on its own. However when it's drive by wire, there is no throttle linkage to pull. From underneath the truck, the rear engine mounts appear to be in good shape; however, the bolts have to be stretched, so we are going to replace the mounts and bolts. This Volvo only has 438,000 miles, so what caused the front engine mount bolts to fall out? If you listen to our radio shows and read these articles, you should know this answer. Torsional twisting, caused by the injectors firing and forcing the piston to the bottom of the stroke, is the cause, and the TORSIONAL DAMPER absorbs the torsional twisting. When the damper is worn out, something has to absorb the vibrations. It's my belief that this Volvo needs a new torsional damper. Many people call it a harmonic balancer; however, the correct name is torsional damper. The torsional damper is a shock absorber for the engine and should be replaced at around 500,000 miles. A worn-out damper WILL break engine parts.             


To err is human. We all make mistakes, and that is how we learn. However, making mistakes on our trucks in the garage can be costly. We recently had a 2019 Peterbilt 389 in our shop with several intermittent electrical issues. The issues started off sporadic and became more frequent. The main issue was a no-start, no-crank issue. The other issues included erratic headlight issues, check engine lights, and aftertreatment issues. The owner had replaced the batteries and starter, and the starter interrupted the relay without success. Whenever we hear of a truck with this many electrical issues, we start by inspecting ground and power connections.

Most of the connections in the battery box were new since they recently replaced the batteries. With a few tests, we quickly found that the fuse box under the hood only had 6 volts going to it. This fuse box

powered several things like the engine ECM, the headlights, trailer lights, the aftertreatment, and several other circuits. We knew we definitely found an issue here. We traced the wiring back from the fuse panel to the battery box, where we discovered that the fuse box connection to the battery was fine. Still, this battery was not connected to the other batteries in the box. Ah ha! We measured 12 volts

on two of the batteries and 6 volts on the third battery. This box only had three batteries. After digging through the loom and zip ties mess, we found the battery was disconnected. After connecting the battery and charging the whole bank, we were ready to start the engine and call this job complete. However, it still didn't start. One of the mechanics noticed that the lift pump on the engine wasn't coming on when we turned the key on. This must mean the ECM is either dead or not getting power. We

checked the fuses, and they were fine. We tried the ECM on the bench, and again, it was fine. So, what we found was that the top ECM connector was broken and wasn't fully seated in place. The

connector was broken from a previous repair where someone tried to either take the connector off or put it back on. These connectors are brittle and break easily. We repaired the latch, and the truck fired

up without issues once the connection was fully seated.


As the holiday season unfolds, we want to extend our warmest wishes to you and your loved ones. May this festive season be filled with joy, laughter, and the warmth of shared moments. We hope you find time to relax, reflect, and rejuvenate, surrounded by the love of family and friends.

Looking ahead to the coming year, we are excited about the possibilities and challenges it will bring. We are committed to continuing our pursuit of excellence and providing you with the highest level of service. Together, let's make the upcoming year even more prosperous.

Once again, thank you for making 2023 an amazing year for Pittsburgh Power. We are truly grateful for the trust you have placed in us. We wish you a joyous holiday season and a Happy New Year filled with good health, prosperity, and continued success.

Written by: Bruce Mallinson, Leroy Pershing, and Jordan Greathouse; Pittsburgh Power Inc., 3600 S. Noah Drive, Saxonburg, PA, 16056. Phone (724) 360-4080 Email: [email protected] www.PittsburghPower.com