Smoke under deceleration

Brbrooks83

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Sep 7, 2019
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Location
Knoxville TN
I have a 1998 4.0 5 speed runs great. But smoke under deceleration like when gearing down to come to a stop or just when I let off the gas blows some blue smoke and smells like oil burning. Any ideas what this could be or ideas to fix it? Thanks
 
I have a 1998 4.0 5 speed runs great. But smoke under deceleration like when gearing down to come to a stop or just when I let off the gas blows some blue smoke and smells like oil burning. Any ideas what this could be or ideas to fix it? Thanks
More than likely valve guide seals, if it's coming out of the exhaust. Under deceleration, increased vacuum in the cylinder sucks the oil past the valve seals.
 
Could be running a bit rich. Under decelerating it is burning less and blowing out some unburned fuel. Have a friend replicate the problem while parked if you can and stand behind the tailpipe. Burning oil will have a definite odor. And unburned fuel will smell like...unburned fuel.
If it is oil then I'm with the above posters.
May, and I mean may, be helped with a switch to a high milage oil that has extra conditioners that could help the valve guide seal a bit.
Also having carbon deposits in the cylinder is a possibility. Spraying a mist of water into the intake can help clear that out.