Lot of white smoke

[matuva]

Howdy all,

here is the story :
a friend recently bought a 1995 Blazer. The Blazer is supposed to suffer from an important engine damage, as said the seller.
The fact is that after an oil change, the mechanic pours in 10 liters of oil instead of the 7, and, after a 1 hour drive, the previous owner saw a bunch of white smoke, with loss of power.
After they reduce the oil level, the Blazer is now always smoking a lot of whit smoke, especially at idle.
This white smoke disappear a few when running.
When cold, the engine stumbles a lot, and when getting hotter, is goes smoother.

Some of us are guessing the turbo bearing are shot, others believe a piston ring is shot or a valve, but what makes me thinking it's something else is that the smoke smells unburnt fuel and not oil.
I hooked the scanner and it shows DTC 92 (cylinder imbalance in cylinder #2), and DTC 96 was stored in the history.

What does mean "cylinder imbalance in injector X" ?

When hot, the truck runs fine, smokes a lot at idle but runs fine, pushes strong.

I did an injector balance with the scanner, and it seems all 8 injectors are working fine.

 

[RadioMan]

You might try clearing the codes and swap that injector with the one next to it and see if the code moves with the injector.

 

[matuva]

That's something to be tried...though, performing the injector balance with the scan tool shows the injectors themselves look OK, but that's something to try...

Correct me if I'm wrong : cylinder imbalance means you may have something wrong with that cylinder that is causing a loss of compression or a loss of combustion on that cylinder.

Is it possible that, because of the excess of oil, a piston ring has broken, and now we suffer loss of compression in that cylinder #2?
The scan tool found DTC 96 in history, but cylinder 6 works fine now.

So, any idea about what should cause erratic cylinder imbalance? I don't understand why #6 has recovered from same disease...

 

[RadioMan]

Here's what I found at http://flashoffroad.com/Diesel/GM99Diesel/6_5LV8TurboDieselFeatures.htm

"Adaptive cylinder balance * Adaptive cylinder balance is included on the 6.5L turbo diesel. This process measures the horsepower of each cylinder at idle and directs fuel to each cylinder accordingly. This results in smoother operation of the vehicle by minimizing the vibration of the engine."

Could it be that a bit (doesn't take much!) of dirt, crud, etc. got past the filters and clogged #6 and it finally cleared but #2 hasn't? It doesn't say at which point, other than at idle, these measurements are taken... All the time the engine is idling??? I'm not sure, but reading the description of how the imbalance is detected, I wonder if even a bad glow plug could cause this fault since the cylinder wouldn't be working right at idle till the engine warms up.

 

[North Maine]

since the cylinder wouldn't be working right at idle till the engine warms up.

I doubt that, because you dont trip those codes when you have GP's failing... last winter my truck only had 4 working and it was shake enough to spill coffee on cold enough mornings becuase only 4 cylinders were fireing at first. I didnt get any codes tho.

 

[matuva]

That happened after the oil change, after the mechanic pour in 10 liters of fresh oil instead of 7. I don't know if it's just coincidence or if it is the key.

Do you think that it the cause of this white smoke, I mean by damaging an internal part? What damages could be caused by excess of oil except seals?

 

[North Maine]

how about you do a compression test?

 

[matuva]

We phone the previous owner. He said he did a compression test : he can't remember wich one, but a cylinder has no compression. I bet it's #2.
Broken ring? The smoke doesn't smell oil...

 

[North Maine]

Hahahahaha well there you go, if one cylinder has zero compression, there is your white smoke. It might be that the turbo/engine/everything gets hot enough after a while that you dont have the white smoke. How is your blow-by? That would tell you if its a ring. Block off the CDR inlet to the the turbo and take off the oil fill cap and see what you get out. If its nothing noticable, i doubt it's a ring, more likly a gasket or valve.

 

[matuva]

OK, will do that. You're probably right. I have to wait untill the owner comes back before testing that.

Do you have any idea of what excess of oil could damage?

 

[North Maine]

Well if you were to fill it up so that there was liquid oil in the cylinder, and then you turn the engine over you are compression a liquid... ie; it ain't gonna happen. Something has to break, the starter, the rod, the piston, the rings. Your guess that its got broken rings sounds fair to me. Also you could probly identify the cylinder that isnt fireing by put a long screw driver to each injector and listening, it should sound different with no explosion coming from it. It could also "coke" up items because it was burned as fuel in the engine, and at a low temp that will really leave some nasty residue.

 

[pc_renaud]

My grandfather overfilled the engine oil in his car once. He thought you should be able to see it filled to the top of the valve cover,he was going senile. long story short he started the engine and cracked a piston ring, but the car would only intermitantly smoke not constant. A compression test is the best way to go to check for broken ring or a possible bent valve.