Ok. Here's my issue.
1999 C3500 dually, 6.5, 4L80, 4:11 gears. 133k. Bought it a couple years ago. Needed a Y pipe. Replaced that, but truck has always smoked under any sort of load. Plus it's a pooch.
I took an interest is fixing this thing up. Checked waste gate operation - not closing at idle. Check fire vacuum at turbo - none. Checked for vacuum at WG solinoid - no. Replaced vacuum pump. Now I have good (great) vacuum at turbo @ idle.
Here's the problem now... turbo operationis intermittent.
Picture this. Stopped, pulling a 1 place car trailer with a car on it. Take off at moderate throttle (half +/-). Truck takes off, pulls good, no smoke. Lasts for 3-5 seconds. Then (I'm assuming) waste gate opens - black k smoke, real poochy. Still holding same throttle, turbo will come back (no smoke, plenty of power). Sometimes boost will last 1 second, sometimes for blocks. No boost is just as random.
I did not change vacuum lines, BUT, testing at the solinoid, both the turbo and pump side will hold 20in of vac for a minimum of 10 min
1999 C3500 dually, 6.5, 4L80, 4:11 gears. 133k. Bought it a couple years ago. Needed a Y pipe. Replaced that, but truck has always smoked under any sort of load. Plus it's a pooch.
I took an interest is fixing this thing up. Checked waste gate operation - not closing at idle. Check fire vacuum at turbo - none. Checked for vacuum at WG solinoid - no. Replaced vacuum pump. Now I have good (great) vacuum at turbo @ idle.
Here's the problem now... turbo operationis intermittent.
Picture this. Stopped, pulling a 1 place car trailer with a car on it. Take off at moderate throttle (half +/-). Truck takes off, pulls good, no smoke. Lasts for 3-5 seconds. Then (I'm assuming) waste gate opens - black k smoke, real poochy. Still holding same throttle, turbo will come back (no smoke, plenty of power). Sometimes boost will last 1 second, sometimes for blocks. No boost is just as random.
I did not change vacuum lines, BUT, testing at the solinoid, both the turbo and pump side will hold 20in of vac for a minimum of 10 min