smoke on startup

[Low87]

What causes smoke on startup?  It's not white, but not black either.  It usually goes away pretty quickly.
When I've parked with the exhaust exiting towards my wife's car, then start up in the morning, the exhaust blows black "stuff" on my wife's car.  Learned real quick not to park that way.  I lose no water, but I do lose oil (no leaks).
I also noticed the last few mornings (it's been pretty cold) that my truck will blow fog(?) considerably longer than my wife's car.

Any guidance would be appreciated.

[firefighter]

Possible bad valve guides.
How many miles are on the motor?

[bd]

Ditto on the valve guides/seals, assuming the initial puff of smoke has a bluish cast - a common condition for an engine with a few years of service on it.  The black soot spotting your wife's car is washed from the walls of your exhaust system by moisture.  Water is a normal by-product of combustion.  Until the exhaust system warms up, the moisture passing through the exhaust condenses.  You'll see water dripping out the tailpipe.  Some of the water remains in suspension due to the exhaust flow and carries soot with it.  You don't need to worry unless the soot has an oily feel to it and doesn't dry out.  The reason for the difference in the relative length of time your vehicles blow "fog" is related to differences in the powerplants, size/length of the exhaust systems, combustion efficiency, ambient temperature, etc.  How much oil are you adding between changes and how often do you change the oil and filter?  How many miles are on the engine?  How is the car driven, mostly short stop-n-go or highway?

[Low87]

Thanks for the quick replies.

The K5 has either 118,000 or 218,000 on it.  It's a daily driver, probable 50/50 on highway vs. city. 

I did an oil change when I bought it in May, and the 2nd just last week (never claimed to be a maintenance king).  It will burn roughly a quart of oil every 3-4 weeks.

How involved is fixing the valve guides/seals?  I've got a relatively fresh crate engine in my 87 that is sitting, I've been toying with the idea of switching the engines.  Gonna be awhile before that happens, have to build an addition onto the house first.

[bd]

So you've added 6-8 quarts since May?  How many miles does that represent?  Unless you fly that thing to Hong Kong every week, the valve guides couldn't pass that much oil....   If you are certain there are no leaks an' the motor ain't knockin', it's probably just worn out....

[Low87]

Big picture it's more like 5-6 quarts since May. That's roughly 6,500 miles.

No leaks that I can find, at least none while sitting. If there's any blowing underneath while driving I'd never know, it's pretty nasty under there. No knocks from the engine.

May just keep it alive til I can swap engines.

[Grim 82]

How involved is fixing the valve guides/seals?

The heads would need to removed. Basic tools & a valve spring compressor, $10 worth of o-rings and umbrella seals and the gaskets to put it all back together would get the seals done, but if the guides are shot you will require machine work which usually costs more than a set of new heads that would most likely be a better design than what you have now. It could just be tired and the rings aren't what they used to be.

You could always just make sure its full of oil and route your exhaust out the back instead of the side to keep the car clean

[bd]

If you run the engine with the PCV valve pulled out of the valve cover, do you get vapor puffing out through the grommet?  Does it have brown oily grunge built up on the end of the valve and under the oil filler cap?  Chances are you're burning most of that oil as it pumps past tired rings & guides.  If you have an EGR valve mounted near the right flange of the intake manifold, it's almost assured you're pulling oil from the valley into the intake ports of the even cylinders past baked intake gaskets.  You could always run a wet/dry compression test to check ring condition (or do a cylinder leakdown test).  Pull all the spark plugs and keep them in order by cylinder.  If the plugs are wet with oil - rings.  If #s 4, 6 & 8 show a large accumulation of "fluffy" coke baked onto the insulators and/or shrouding the ground electrodes, then the intake gaskets are leaking along the right side due to baking from exhaust heat through the EGR.  The valve guide seals & o-rings are guaranteed to be toast at your mileage if original.  If you DO have a lot of ashey buildup under the valve covers DO NOT switch to a high detergent multi-vis oil w/o first making repairs or the problem will worsen - and it will start to leak externally!  There might be hope depending on how energetic you feel.  If you do deceide to replace the valve guide seals, abandon the umbrella design and use Viton press-ons for a positive seal.  Good luck. 

[Low87]

Great replies, thanks!  Heading out for the weekend so I won't be able to look at this stuff for another week. I'll let you know how it goes.

[str8bloc]

mine looks like this does yours look the same from the oil fill tube?

[bd]

M-A-Y-O-N-N-A-I-S-E ! 

[beastie_3]

oh no

[VileZambonie]

I agree with BD - and if you aren't going to rebuild anytime soon replace the valve seals with positive seals as mentioned.