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1995 4.3L Vortec vin W blue smoke out exhaust

capterics

By capterics
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capterics New Member

capterics

Posted
Posted

Hello,

I have a 1995 GMC Jimmy w/ 4.3L. 171000 miles. Problem: There is blue smoke coming out the exhaust, intermittently. Runs fine, oil pressure is 45 psi @ idle. I drove it about 100 yards and it was smoking like crazy, shut it off and restarted 1 hour later... no smoke! Just started doing this today. The tranmission rear seal leaks and is overfilling the transfer case. I drained 1 gal out of the Tcase and topped off the transmission. Thats when it started smoking. The 4L60E trans has no vacuum controls, except for the 4X4 and looking through AllData I cannot see a corrilation that would allow trans fluid in the vacuum system. I am an ASE Master Tech (20 years) and have never run into this. This is my vehicle. Ideas??? :freak:

 

aflesch Enthusiast

aflesch

Posted
Posted

Did the T-case vent line accidentally get connected to vacuum?

capterics New Member

capterics

Posted
  • Author
Posted

I was thinking valve seals also, but when they are worn it will smoke w/ cold. No work has been done to the transfer case / no lines crossed. It smokes w/ warmed up, and it just happened. I'm thinking a possible broken oil control piston ring?!? PCV system is good, also.

Thanks for the input!

aflesch Enthusiast

aflesch

Posted
Posted

A crack in the head or block might open up when it gets hot and the oil thins out.

capterics New Member

capterics

Posted
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Started it up this morning and it smoked about 1/2 as bad and I had not done anything to the engine. Originally it started smoke like turning on a light swich... just BAM. Bad enough to get a ticket, so I had friend pickup some "No-Smoke" last night because I was afraid to drive it. I used my evacuator and pulled 1 pint of oil out the dipstick tube and poured it the "No-Smoke"... test drove it and the smoke is gone! In a pinch, I swear by that stuff.

 

I was thinking valve seals, but I had a '84 K Jimmy 5.0L and it smoked when cold and then went away when it warmed up... valve seals fixed that. I have no blow-by what so ever, but I would be willing to bet it is a problem with an oil control piston ring. Every engine I've ever rebuilt had heavy carbon build up in that ring. I could put 2 quarts of ATF in the crankcase and see if it desolves the carbon, but that could cause more problems with this high of mileage. Nope, I'm done... It's a great vehicle but I'm not pulling the heads or rebuilding it. Just not worth it!

 

Thanks for all the help, and consider this case closed!!! :D

  • 6 months later...
capterics New Member

capterics

Posted
  • Author
Posted

I found the problem! The front seal in my transfer case is bad and the Transmission fliud is over filling the transfer case. The transfer case vent line is the same line as the vacuum control line for the four wheel drive. Fluid is being sucked into intake manifold and the vaccum reservor has transmission fluid in it. Now my heater rotory valve is not working. UG, time to tear the dash down.

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