VOLVO PROBLEMS SOLVED. Did I hear someone say a Volvo with a Volvo engine never breaks down? Well, guess what? We recently had 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 very surprised the engine was still in the chassis!
If this had been a mechanical engine with an actual old school 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” like it is today, there is no throttle linkage to pull. From underneath the truck, the rear engine mounts appeared to be in good shape, but the bolts needed to be stretched, so we went ahead and just replaced the mounts and bolts.
This Volvo only had 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 the 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, but 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 cause engine parts to break.
TROUBLE WITH VOLTAGE. 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 then became more frequent. The main issue was a no-start, no-crank issue. The other issues included erratic headlights, 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. After 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 had 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 tie 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 meant the ECM was 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. 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 then the truck fired up without issues once the connection was fully seated.
HAPPY NEW YEAR! 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, we can make the upcoming year even more prosperous. Thank you for making 2023 an amazing year for Pittsburgh Power. We are grateful for the trust you have placed in us. All of us (Bruce Mallinson, Leroy Pershing, Jordan Greathouse, and our entire team) at Pittsburgh Power hope you had a joyous Holiday Season and that your new year is filled with good health, prosperity, and continued success.