Black Smoke

[chrisangelski]

I started the another poor milage thread with the intent of being able to figure out whats bugging my milage on my 1997 6.5 turbo 4x4 vin S 1500 sierra. I have tons of black smoke when accellerating and a loss of power. I have 2 codes popping up: P0256 and P1191(boost/supercharger cicuit a performance and intake air duct leak). I have checked the vacuum at the wastegate=18", turbo boost at 1800-2000rpm=2-3lbs, wastegate arm is working, turbo temperature sensor on top of intake was covered in oil, egr seems to be fine, clean and new air filter and fuel filter, I changed the mass air flow sensor. I just dont understand why she is pouring out so much black smoke under accelleration, no smoke at idle, a little black smoke under normal/slower driving conditions, tons of black smoke when you step on it. Why is this thing getting and burning so much excessive fuel. Any suggestions?

[6.5 Detroit Diesel]

maybe some of the TDP guys who are more technically oriented then myself have another reason, but.

my truck recently was doing this. loss of power, black smoke, vacuum was working. replaced the turbo, (converted to mechanical wastegate), and got my power, mileage, and boost back. lost the excessive black smoke. might be an idea......

[JohnC]

One thing that is often overlooked is the circular gasket on the EGR chimney between the upper and lower manifold halves. Sounds like you may have an EGR issue.

What is your boost at 2000 RPM under heavy throttle? (Should be about 8 psi.)

[chrisangelski]

@2000 rpm i get 3lbs of boost. thats when im driving around 60-70km/hr and I hit the throttle, my guage is older so it could be out by maybe 1lb at most.

[JohnC]

If you can't get more than that, it's way too low. Could be a boost issue or the EGR could be preventing it from building boost. The boost circuit is easy enough to diagnose. It's been covered innumerable times here in the past. I guess I'd start there.

[DaveBr]

If your turbo is pooched you won't make boost. Take the inlet off the turbo and check for end play and side play on the shaft.

[6.5 Detroit Diesel]

If your turbo is pooched you won't make boost. Take the inlet off the turbo and check for end play and side play on the shaft.

this is what i said dave. sometimes you just beat your head against a wall, and you beat it some more......

just joking.

[DaveBr]

It feels really good when you stop!!!!

[rustyk]

Don't overlook the air filter...

[chrisangelski]

definetely a dead turbo. Now to find one. I live in London Ontario, any suggestions?

[DaveBr]

Check out kijiji or Ebay.

[JohnC]

definetely a dead turbo.

This is a very rare occurrence. What lead you to this conclusion? I've seen worn turbos that sounded like police sirens and were pumping vast quantities of oil into the air that still boosted fine...

[6.5 Detroit Diesel]

This is a very rare occurrence. What lead you to this conclusion? I've seen worn turbos that sounded like police sirens and were pumping vast quantities of oil into the air that still boosted fine...

how is it a very rare occurence?

went back and forth, did four turbo swaps, checked the vacuum system, deleted the vacuum system, and discovered that even though the turbo made no weird noise and burned no oil through, it was definitely making no boost

[DmaxMaverick]

This is a very rare occurrence. What lead you to this conclusion? I've seen worn turbos that sounded like police sirens and were pumping vast quantities of oil into the air that still boosted fine...

Ditto. A turbo that won't make any boost should show a very obvious reason. Either the turbine and/or compressor would have to be worn down to nothing, spindle seized, or it's something else. The wastegate or wastegate control system, fueling, or EGR are much more likely suspects.

[JohnC]

I'm gonna guess 99.44% of turbo failures fall into the following:
1) seized.
2) so badly worn the impeller rubs on the housing and won't spin up.
3) eroded turbine or impeller blades.

All are obvious except eroded turbine blades, which is only going to happen if something big and solid passes through the exhaust.

[chrisangelski]

I changed the EGR, MAP, fuel filter, Maf, seen oil leaking from turbo then cleaned it to verify that it wasnt coming from the tube from valve covers, drove 300km and put a gauge to meter the turbo and got 2-3lbs @2100rpm, took the rubber back off and seen oil from the turbo, I now know the seals are pooched and there is play in the spindle. Turbo is finito.

[6.5 Detroit Diesel]

Ditto. A turbo that won't make any boost should show a very obvious reason. Either the turbine and/or compressor would have to be worn down to nothing, spindle seized, or it's something else. The wastegate or wastegate control system, fueling, or EGR are much more likely suspects.

im not saying that it happens a lot, but it does happen. i went over everything BUT the turbo itself multiple times, and everything was fine. change the turbo and boom, boost back

[racer55]

At cruise you won't see very high boost #'s with a stock system,it takes load like climbing a hill or towing to get boost to increase.
With a turbomaster the result would be different though-they don't care about engine load,you just get the boost that you have it set for.

[Yukon6.2]

Hi
90% of 6.5 turbos will have oil on the blades and housing on the intake side,probly a higher persentage as the CDR dumps oil into the intake boot on the turbo.There will be play in the spindel as well.So long as the wheels don't touch the housing the play is fine,when the motor is running the oil preasure takes up this play.
Hate to see you buy a turbo and not need it.
Thomas

[DaveBr]

Hi
90% of 6.5 turbos will have oil on the blades and housing on the intake side,probly a higher persentage as the CDR dumps oil into the intake boot on the turbo.There will be play in the spindel as well.So long as the wheels don't touch the housing the play is fine,when the motor is running the oil preasure takes up this play.
Hate to see you buy a turbo and not need it.
Thomas

Play in the spindle is not acceptable. When that happens its time to find a new turbo as you don't got much time left.