Turbo Diagnostic

[SixBuy]

I know this has been addressed somewhere not too long ago but danged if I can find it!

Been chasing down the source of slobbering and HUGE clouds of white smoke on acceleration - the harder the acceleration, the larger the cloud! Had fuel injectors cleaned, set etc. - no change. Disconnected air intake from turbo and no change. Turned turbo by hand and it turns smoothly but does not 'freewheel'. Connected a vacuum/pressure gauge to the intake manifold at the 1/8 pipe plug just above the flame heater and about a 1/2 inch of vacuum present - no positive pressure at any rpm. Does this mean the turbo is toast?
Buy or rebuild? New or used? Is it worth taking it to a turbo shop?
It's a -1D. Comments welcome...

 

[Westech]

sounds like the oil seals are shot and oil is flowing in to the exhaust, thats where the white smoke comes from. Or your burning coolant, the other way you can get clouds of white smoke. check to see if your oil or coolant is low, and pressure check the cooling system. have to start someplace.

 

[jwaller]

white smoke is usualy water in gas engines. sounds like maybe a head gasket. have you checked to see if you have bubbles in the coolant or are losing any coolant?

 

[Trango]

Can you smell the diff between oil and diesel smoke? There's a definite difference. Oil smells more "coked".

 

[SixBuy]

There's no white smoke at any throttle setting, just on rapid acceleration (a blip on the throttle will do it). Coolant is clear, no bubbles. Oil OK. Still wondering about the boost pressure - Shouldn't there be at least a few psi on the intake manifold at idle and go up with RPM?
The smoke is actually a grey/white cloud that leaves black oily streams running down the exhaust pipe.
And the smoke has a definite diesel/kerosene odor to it- seems to fit the description of unburned fuel.

 

[rdixiemiller]

Can you borrow a turbo to swap and see if that fixes things?

 

[cranetruck]

At idle there is virtually no boost. You need to load down the engine, take her for a ride.

 

[SixBuy]

I guess I'm having trouble getting my gasoline mind around diesel concepts! Since there is no throttle plate, manifold pressure is essentially ambient pressure. When you add a Turbo you are boosting ambient to some positive pressure. Seems like the higher the engine RPM, the more exhaust flow, the faster the turbo spins, the more air compressed, the more air volume consumed. Looks like it could be a wash between in and out flows. So you're saying that loading the engine causes the Manifold Air Pressure to rise? And kicking her up to a fast idle, say 1500 - 2000 RPM still produces no boost? The only fluctuation I get is betweem 0 and -1/2 inch vacuum - never goes positive. Guess I slept thru Diesel 101...

Yeah wish I had another turbo, gaskets , etc to swap...
Time to quit trying to outsmart it!

 

[WillWagner]

There should be no vacuum. A diesel doesn't make it. Try leaving the gauge hooked up and just drive it a short distance. Grey/white is incomplete combustion or a timing issue A pintle in a nozzle stuck open, a delivery valve in the pump, pump timing, air in the fuel, high fuel restriction, low fuel pressure on the low pressure side, (lift pump in the tank,) just a few items to check. PM me if you need some help.
Will

 

[SixBuy]

Thanks Will, I'll try those this evening. I just got the nozzles back from the shop so hopefully the pintle is not an issue. Bled air out of the secondary filter bleed with engine running - can't see bubbles in the nozzle bleed return line anymore. Lift pump seems to be ok but haven't measured pressure. New filters in all three cannisters. Pump timing and delivery valve are candidates...

 

[DrFoster]

Just popped my head in here. The Turbo Dr. Is in... How can I help?

 

[m35a2cowner]

White smoke

Do you see this smoke after you have driven the truck some distance? You might be actually seeing steam from rain water that has gotten in the stack or from moisture (a normal product of combustion) that condensed in the exhaust pipe. Unless you drive the truck some distance, especially in colder weather, the pipe away from the motor will not get hot enough to vaporize all the moisture that may be laying in the pipe to the point where it goes straight up and out the stack. Idling or short trips are not enough to do this. The streaks you see might be water washing the soot off of the inside of the stack. If I remember my trade school classes correctly the operation of the turbo is a function of heat from the exhaust gasses rather than flow of exhaust gas. Notice that you always begin to hear the turbo wine when you start climbing a hill but it quits when your done or traveling on level ground. I think its caused because when the engine is working there is more fuel in the combustion chamber and some small part of it continues to burn on its way out of the cylinder and as it burns continues to expand the exhaust gasses which occupy more volume in the in the pipe and exhibits a greater pushing force of the exhaust vanes on the hot side of the turbo. This force is transmitted to the compressor side which packs more air into the intake manifold thus giving you boost. One more thing, the turbo shaft rids on a cushion of oil (much like the oil in between the rod bearing and the crank journal) so it won't necessarily free wheel when there is no oil pressure. The reason you are suppose to let the engine idle 10 minutes or so after a trip on the highway is to allow the free wheeling turbo to slow down so that once you shut the engine off and the oil pressure stops it won't be traveling at a high rate of speed and damage the bearing or shaft. Hope that helps

 

[DrFoster]

Nah he was saying white diesel smelling exhaust

That could be a number of things. It could be as simple as a cylinder not firing, or a stuck injector flowing WAY too much...

 

[SixBuy]

OK, I sent the injectors to the shop for cleaning/testing and checked the compression while they out; 500 lbs +/- 10 on all cylinders. Other than a thin bit of light blue oil smoke, the engine does not smoke at any RPM UNTIL you hit the throttle. The size of the grey/white smoke cloud is directly proportional to how much and how fast you hit the pedal. It'll blow as big a cloud at 2000 RPM as it will at idle. I really didn't want to pull the injection pump until logic dictates- that's $$ just to get it tested not to mention the hassel factor...
I'm still amazed I've never seen any positive MAP; just 0 to -1/2 inch regardless of RPM going up or down. And it doesn't seem to make any difference whether the engine is hot or just warming up.
Oh well...

 

[DrFoster]

You might have a boost leak. Otherwise, the turbo can be frozen. It will run with it like that, and because it only produces so little additional power, it may or may not be noticeable right away.

I guess I should ask, can you hear the turbo?

If you take off the intake side of it, does it spin? Without the engine running, and everything cool, can you move it EASY with your fingers? The impeller should spin freely.

No pressure and no moving turbo vanes is simple. No pressure and a moving turbo might be a missing connection on the intake.

That explains the extra fuel in the exhaust in a way. The pump is not "smart" enough nor is the deuce advanced enough to have a MAF sensor to adjust the metered amount of fuel. If the turbo is dead or siezed, then the pump will still blast a unchecked amount of fuel into the system, regardless if there is enough air in the cylinder to burn it.

 

[rizzo]

You might have a boost leak. Otherwise, the turbo can be frozen. It will run with it like that, and because it only produces so little additional power, it may or may not be noticeable right away.

I guess I should ask, can you hear the turbo?

If you take off the intake side of it, does it spin? Without the engine running, and everything cool, can you move it EASY with your fingers? The impeller should spin freely.

No pressure and no moving turbo vanes is simple. No pressure and a moving turbo might be a missing connection on the intake.

That explains the extra fuel in the exhaust in a way. The pump is not "smart" enough nor is the deuce advanced enough to have a MAF sensor to adjust the metered amount of fuel. If the turbo is dead or siezed, then the pump will still blast a unchecked amount of fuel into the system, regardless if there is enough air in the cylinder to burn it.

I was just gonna tell him that.

 

[DrFoster]

I should edit this a bit:

If you take off the intake side of it, does it spin?

I meant to say to test this when the engine is running. Remove the intake and LOOK at the vanes spinning with a flashlight. This is a way to see if the exhaust vanes are at least there and not frozen, or if the darn driveshaft on it isn't broken.

Anything after that, like sticking your fingers in there, is strictly for when the engine is off, or else you'll be making a visit to me.

 

[WillWagner]

Are you sure the smoke smells of fuel? A turbo that isn't working will usually have symptoms like slow acceleration, dark/black smoke, low power and if there was an air leak between tho turbo and engine, you would hear a loud noise like air escaping or a double whistle, one being the normal sound the turbo makes and another, slightly lower in pitch, of compressed air finding it's way to atmosphere. It isn't hard starting is it? Like it turns over then wants to "stick" then turns over. The intake manifolds on these are water jacketed. Maybe there is a pinhole in the casting and a small amount of coolant is getting into a cylinder. This is a good one, one of the things that when you find the cause, you'll not forget for a long time!

 

[DrFoster]

True, but I'm thinking that he probably knows what stink is what stink, and the stock turbo puts out such a low amount of power that you probably won't notice much difference on this motor unless you normally race your rig everywhere. It will drive a bit more "choked" but nothing like a 12.7L cat motor that depends on the turbo to run properly.

White smoke sounds right for unburned diesel. Unburned other types of oil are white at vaporization temps. We would get it on ours in the winter in the Marines, along with the 5-tons too - until that cylinder got going and the fuel flooding condition went away. Black would be carbonized (or burned, I'm not sure what the correct term is here), right?

 

[m35a2cowner]

smoke

Any chance the air filter is very dirty or plugged? This would result in smoke when accelerating (although it would seem as if it should be black) and no boost as the turbo would be starved for air. Take the filter out and drive it (only very short period of time) and see if that makes a difference. Might also take a look at rubber hoses (intake) to see if any are soft and may be drawn together when vacume is high. It doesn't cost anything and might be the problem. Let us know, as inquiring minds want to know.