The 444 seems to have developed some sort of fueling issue recently.
If any of you are familiar with I-70 east of Denver, you'll know of the small hill you come up going West into Denver right before Bennet. As I was pulling this hill I seemed to have an issue develop. I'd work to about 22lbs of boost pressure when suddenly I'd here a pop (more like a hollow thump) and I'd lose boost, it'd drop to 20lbs and then work back up, any time you tried sustaining 22lbs it'd pop again and drop manifold pressure.
My first concern was the turbo was going out. I looked in the mirrors and saw no white smoke.
I'd eased her over the hill and into the truck stop on the other side. Opened up the engine to see if there were any issues developing. At idle she sounded just find, no excessive noise, and running clean (well, as clean as a Big Cam will, I've noticed even with STC, on a cold night, they'll still smoke just the tiniest bit).
The next thought was a fuel filter plugging. I parked the truck for the night (luckily, close to home) and got home, came back in the morning with a friend and mentor of mine who has worked on Cummins engines for 50 years. We pulled the fuel filter and it looked totally fine. No sign of plugging, no sludge like algae in the diesel or something.
We put the new filter on and started the 444 up. It idled appropriately, cleaned up, no smoking.
When we fed the engine throttle however, the engine began smoking white smoke badly as well as some backfiring (although, I'm more given to believe the backfiring was due to the engine running cold and precombusting). Again, our concern became the turbo again. We pulled the elbows and inspected, no excessive play, and ZERO oil whatsoever on the hot or cold side. Totally bone dry.
We listened to the engine. There was no knocking, rattling, or hissing as if there were issues like a burnt of dropped valve, dropped injector tip, etc.
I spoke with Geoff on the phone a bit recently, and I'm looking for any other Cummins' mechanics opinion:
We think it's down to one of maybe three different things:
1.) There's a block somewhere in the fuel lines near the tanks, a rag, toilet paper, god knows what, got into the tank and is restricting the flow from the tank (They're bottom draw tanks).
2.) The STC valve has gone bad and is stuck in the advanced setting, not allowing the timing to retard for proper firing under loaded conditions.
3.) The diaphragm on the PT pump is damaged.
Any opinions or advice is welcome from those well familiar with Cummins engines.
Troy
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