The Backstory:

The Old '94 C2500 seems to be having trouble with the turbo.
It has been like this for probably 5,000 miles maybe more, who knows. :shake:
It was being used as a ranch pickup that the hired men chased cows with
but has now become my adopted project because I need a pickup to go back to college with...

I've been trying to get the turbo to work properly since I started tinkering with the truck but without much luck.
-Fixed the crosover pipe, Still smoked badly.
-Replaced the wastegate control module, PCM, Fuel Filter, Glow Plugs, and now only smokes under load.

Get a SES light under load when I get on it, but goes away when I let off. When accelerating, greyish black smoke, then BILLOWING black cloud if I go WOT.

Planned on making my own TM so I Finally installed a boost guage. Reads 0 lbs 95% of the time.
Thought guage might be off, but noticed (by applying tongue to tube) that it actually pulls a noticable vac at idle?!? :wtf:When I REALLY get on it I can get it up to 3 or 4 lbs. Wired wastegate SHUT and could only get it up to 5. I didn't notice any leak in the intake and figured that it didn't have one since it actually seemed to pull a slight intake vacuum. I'm thinking there must be a leak in the exhaust? The cross-over pipe was badly damaged due to some serious abuse and I have replaced it but it looks like it may still be leaking a bit at the donut. Maybe a crack in a manifold or turbo housing that I have not found, but there are no other blatantly obvious exhaust leaks. Would this be enough to loose that much pressure? Could the turbo be bad?

Any helpful tips would be greatly appreciated.

Thanks!

.

A leak in the cross-over can definitely affect the boost you get. If you get 5 psi, at least the turbo is spinning. Also look for cracked exhaust manifolds. If the cross-over was damaged, it could have cracked the manifold as well. That's the only thing holding it onto the truck.

Pull the output tube off the turbo and check for any endplay in the turbo. That might let you know if it's been abused much, and I think it probably was.

Jake

Might be worn enough to drag on the housing slowing it down.

I whacked my crossover cutting firewood in the res. It was noticibly leaking and I still had boost, but that was one instance.

I've had some luck with the home made TM.

It seems like it takes a lot more pressure to hold it closed that I thought. Maybe I didn't have it tight enough when I wired it closed the first time. I'm sure the leaking crossover pipe is not helping that.

I hooked onto the horse trailer and went up and down the road a few times to dial her. I've cranked it up until I was getting near 10 when I pulled hard, but I'm scared to even try to go any higher than that, even if just for kicks and giggles. The old girl is pretty tired and has had a lot of abuse in 'er day. I still get a little smoke on acceleration, but nothing I wouldn't expect from an old motor. It still seems like I get a lot of smoke at WOT, but at least now she is pulling hard when WOT and not falling flat like before.

The turbo spun freely, didn't seem to have any endplay, but there was a lot of oil in and around it. But on this old engine its hard to find a place that doesn't have oil... I've got quite a bit of blow by so I'm sure that doesn't help either. How does one know when the turbo is starting to show excessive wear? I'm not looking to have a ton of power, I don't think she can handle it. Maybe run her just a little above stock What is a good safe range to run the turbo in?

As far as I know shaft play is only indicator of turbo wear. If you still have stock pcm might want to stop where your at so you don't cause codes. I have a chip and have seen 13psi.