afecko
10-10-2001, 09:17 AM
I’m about at wits end with a 1990 Cummins that I’m working on. About a year ago, while out cutting a Christmas tree at 7,000 feet, I started her up at the end of the day, and a plume of white smoke started flowing out of the exhaust. This was the first time in 4 years of ownership that this happened. It has continued to this day, the colder it is, the worse the smoke, the higher in elevation, the worse the smoke. It abates a little after warm up, but is present under power. The exhaust has an acrid smell to it, like partially burned diesel, and the wall in my garage is stained from the smoke it produces during warmup. The truck has 160,000 on the odometer, it’s equipped with a Banks PowerPack, and a Pre-Luber. To date I have checked or replaced the following items and systems:
1. Head gasket replaced, head machined, valve seats checked for cracks, head magnafluxed. No problems seen.
2. Injection pump replaced and timed. The pump was going bad anyway, the truck was dying at stoplights.
3. Intercooler checked for leaks. Negative.
4. Compression test. 470 pounds across all 6 cylinders.
5. Injectors replaced.
6. Fittings on high pressure fuel lines checked. Negative.
7. All low pressure fuel lines checked for air bubbles. Negative.
8. TDC timing check. I suspected that the Cam/Injection pump timing gears had broken their keys and slipped, but a dial indicator on the #1 piston showed perfect TDC on the injection pump.
Does anyone have any idea what the hell else could be wrong? I replaced the primary (low pressure) fuel pump 2 years ago due to leakage. It doesn’t show any leakage now.
The fuel mileage is excellent, but the truck does seem down on power a little.
Any and all hints appreciated.
ANDY
1. Head gasket replaced, head machined, valve seats checked for cracks, head magnafluxed. No problems seen.
2. Injection pump replaced and timed. The pump was going bad anyway, the truck was dying at stoplights.
3. Intercooler checked for leaks. Negative.
4. Compression test. 470 pounds across all 6 cylinders.
5. Injectors replaced.
6. Fittings on high pressure fuel lines checked. Negative.
7. All low pressure fuel lines checked for air bubbles. Negative.
8. TDC timing check. I suspected that the Cam/Injection pump timing gears had broken their keys and slipped, but a dial indicator on the #1 piston showed perfect TDC on the injection pump.
Does anyone have any idea what the hell else could be wrong? I replaced the primary (low pressure) fuel pump 2 years ago due to leakage. It doesn’t show any leakage now.
The fuel mileage is excellent, but the truck does seem down on power a little.
Any and all hints appreciated.
ANDY