Probably a dumb question, I have seen these questions before but can't remember...but, I have a 1983 Chevy Blazer with the 6.2l. It's got about 110k on it. It's got some whitish smoke nearly all the time it's running but when I go up hills and have to get on it I get some seriourly BLACK smoke! It's pretty embarrassing when you cannot go up a hill without smoking out the people behind you! Any info would be helpfull. Thankshttp://www.dieselplace.com/forum/smileys/Confused.gif Edited by: cdmasm

The 6.2L is very underpowered, only around 165 HP on a good day. The black smoke is the nature of the beast so when you are pulling a hill it is doing all it can. The white smoke is another matter. Does it smoke even when it is warmed up. White smoke on a cold start is just unburned fuel.

White 'vapor' is unignited fuel, which never reached combustion temperature. This can be 'normal' on cool-to-chilly mornings and cold days. Not normal if engine is at operating temps, over 180deg engine coolant temperature, warm weather.


Black smoke is unburned fuel, at or above combustion temperature, where oxygen was consumed and fire went out. This can raise exhaust gas temperatures to dangerous levels, if pulling heavy loads.


Both symptoms together can result from several causes.


1. Dirty air filter - where engine cannot pump enough air to sustain combustion for amount of fuel injected. Also, obstructed air path into and thru intake ducting. Requires inspection and correction.


2. Low grade fuel, dirty fuel, etc - may need some cetane improver.


3. Inj pump has been 'turned up', attempting to increase power. This is an internal adjustment, somewhat difficult, so most folks do not attempt it.


4. Advance mechanism is stuck or sticking. On a cool morning, engine cold and idling, remove the wire from the terminal on the passenger-side of the inj pump. Rpm should noticeably change. If not, check the wire connector for +12v. If not, the Cold-advance switch is on the passenger-side head, at the rear exhaust port area. Turns on when cold, turns off when coolant temp is above 80deg, or so.


If all is ok, press the mechanical advance lever, on the passenger-side of the inj pump, inward at the bottom. Again, idle rpm should change noticeably.


5. Leaky injectors, where the injected fuel is not fully atomized, retarding\degrading the combustion process.


You might check these things, starting with simplest #1 and working down.

Thank you very much for your input! I'm not what you call "mechanically inclined" nor can I find the time to study up. I did change my air filter, it was SO filthy. My hands were quite greasy or oily is that normal for an air filter? Hopefully not a major issue. I went up a hill shortly after and didn't notice as much black smoke!

You might set up a maintenance schedule to check the air filter at 6 month intervals - should indicate a problem with excess oil accumulation in the air filter.


You might also check the intake ducting for leaves, and etc, starting at the radiator bulkhead, thru the centrifugal water trap, silencer, etc.