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Slight smoke while downshifted

JohnJohn

Member #42
Location
Austin, Texas
bought a new rig 89, 4.0L, 76k, auto

Oil change sticker in rigs window tells me that it has only been driven 6k miles in the last three years. Oil looked about that old. So I put a can of "Restore" in it, let it run, then changed the oil. While driving this evening, with my dad following, I downshifted while going about 55mph. I saw in his headlights a small amounts of smoke coming from tailpipe until I let off the peddle. Clicked into Neutral and roll up the RPMs. A little bit of smoke but not as much. It was definitely coming from the tailpipe side of the car. While downshifted the smoke seemed to let up as I stayed on it longer.

- Could it be the leftovers of the old oil and can of "Restore" burning off?
- Valve job?
- blowing out 2years of crap?
EDIT: could it be an old tank of gas also?

Any ideas?
 
Last edited:
Sticky rings.
Three years since the oil change, so the rings may be stuck in the grooves. I read here something about running ATF through your engine for a short while to clear these problems. Run a search and you'll find it.
 
Smoke on deceleration is related to an increase in vacuum. More than likely the valve seals and valve guides. There is one more possiblility. It could be antifreeze from a leaky head gasket. Check the rear window with a piece of Kleenex, there should be a coating on it. Smell it. If it smells sweet, it is antifreeze. If your hardcore, taste it. It will be sweet if it is antifreeze.:lecture:
 
I drove it around for about 2 hours this morning, and no visible smoking. I even ran it up to about 95 on the highway. Nothing on downshift at all. I only saw it last night in the headlights behind me. After driving it around I let it sit in my driveway for about 10 minutes running. No smoke during that either.

I thinks it needs a can of BG to clean up the injectors and another fresh oil change to get all the "restore" out of the motor.

What do you think now? Should I be concerned?

Thanks!
 
If it quit I wouldn't worry too much, but I would go ahead and get the emissions while things are looking good.

An old trick to help the valve seals after you do the emissions is to add a quart of ATF and about 4 oz of lacquer thinner. The ATF is extremely high in detergent and the lacquer thinner will soften the seals and make them more pliable. Run this for a few hundred miles and change the oil again along with the filter.
 
Make sure and run the BG all the way out of the tank before doing emissions. The BG44K is great stuff but can interfere with emissions due to cleaning out the crap.
 
I think I figured it out. I dro ve behind the wife today.

The muffler is full of rusty crap. The smoke that came out was very brown and rusty looking. It needs a new muffler. I think the extra exhaust the motor creates when downshifting is blowing by all that crap and coughing some of it out. That would explain why it's not as bad now as it was before.

eehhh?
 
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