thanks all for the input. any tell tale signs other than the white smoke that would indicate a gasket (head or intake) issue.im leaning towards coolant leaking into combustion chambers and than burning off.too much smoke in my opinion to be condensation. also would the occassional pinging sound be caused by the coolant burning off. doesn't ping all the time,but when first purchased (6-7 yrs ago) the truck had very bad pinging sound upon accelleration. took it to a chevy dealer where i was told it needed an intake manifold gasket,which was replaced as well as a complete tuneup. had a fuel issue a yr ago in which the infamous spider was replaced and it turned out to be a bad fuel pump. bad diagnosis from my now ex-mechanic and ignorance on my part,so i need to be sure and get it right the 1st time now. should it be an intake gasket leak what can i expect to pay for this repair. no time and not schooled enough to do it myself. again,thanks to all.
das96blazer,levittown,pa
4dr 4wdlt

 

X2! In my experience that is the easiest and most accurate way to tell. If the plugs look fine, then you almost certainly aren't getting water in the engine. Also, mom's silverado with 25K on the clock does the same thing because around here it's real cold! Without a catalytic converter, your engine puts out white smoke almost all the time because the exhaust is so cool when it comes out. Give us the ambient temp when this is happening. It is probably going away because after some time your cat heats up and is turning the vapor (that you can see) into steam (that you can't see) combustion produces water, and a lot of it.

Hope this helps!

Regards,

Thomas

 

Well, being a '96 he better have a cat on it.

 

pop your radiatior cap off. with it not running of course. the engine has to be cold to do this. like overnight. start it with the cap off. if you see bubbles in the radiator its got a bad head gasket. be quick about it too.then get your cap back on

 

Yeah, I learned about putting the cap back on the hard way with my friend's minivan! But again, you can test that, but if the plugs are clean, then it'd have to be a pretty small hole in the headgasket -- like too small for coolant to go through.

As for having a cat, let's just say I was providing an example.

Regards,

Thomas

 

From my experience a blown head is almost always a constant fog as the engine is running and always gets worse rather then better when under load. This doesn't sound like what you describe.
The lower intake gasket having a slow leak is also possible, though you did mention that is was recently replaced.

The sweet smell that you mentioned does usually point to a coolant leak somewhere. However it may not actually be the cause of the smoke. If you have even a slight drip that lands somewhere hot such as the exhaust manifold you will often get that faint whiff of frying coolant. The hoses to the heater core are usually good places to look for this problem since a small drip from one of them can run down to all kinds of places that can flash boil it.

Other things to check for smoke causes are a faulty pcv valve. If the valve is sticking open on startup a small amount of oil can get sucked into the intake. When the engine is still cold this can often burn off as a light blue or gray smoke. However if it is cold out the blue can be easily missed.

Another possibility is transmission fluid entering a vac line from a bad actuator/solenoid. It is an uncommon cause but some types of tranny fluid burn a light gray color. Though burning tranny fluid is a very distinctive odor and once you have smelled it you will never forget it.

The last possibility Is that your truck is running to lean at startup. Just as an engine that is running rich will blow black smoke an engine that is running lean can blow white smoke.

There are several things that can cause you to run lean such as a bad O2 sensor, or a plugged EGR or sticky IAC valve, even a dirty fuel filter under the right circumstances, a vac leak somewhere, dirty air filter faulty temp sensor ect...
A lean condition isn't usually reported with a code until the truck enters closed loop when it warms up and the computer can't correct for it.

At 180k miles fixing this could be as simple as giving your EGR, IAC, MAF,PCV and intake a good cleaning to remove all the carbon and gunk buildup.

Have any throttle response issues or hesitation to immediately start, or gas mileage issues shown up recently?

BTW, running lean would also cause your engine pinging.

 

hey awe341,thanks for the help and input. yes, gas mileage has been really bad lately (lucky to make 160 mi to a tank) and i did notice some hesitation and miss firing as well while accelerating which set off the infamous codes (po3xxx) at least 1x a week.this led to a complete tuneup around xmas time. gas mileage got a little better but codes still appeared. changed the ckps last weekend and i finally made it to 200 miles per tank and so far no more miss fire codes.
started it cold this morning with the cap off and no signs of bubbles in the rad.
i will tell you what i have or know of that has been replaced.
egr..replaced 6 months ago with one from auto zone.re-checked last weekend and there is no sticking and slightly discolored black but no carbon build up.
maf...abt 1 year ago replaced with one from auto zone.
pvc...replaced last weekend
fuel filter...replaced abt a year ago along with fuel pump and spider (chevy dealership repair)
o2 sensors...replaced the one right before the cat 3 mos ago.
iac & temp sensor...never replaced as far as i know of.
i do believe and/or hope it is just running lean and there are no gasket leaks. i hope with 180k that i am not expecting too much...shld run better with more pep and better gas mileage. look forward to your replies.

 

If you can get an advanced scan tool and look at your fuel consumption at idle, I'm running pretty well and when the idle goes down in the 500-650 range, I see 0.44GPH. I don't remember the consumption from a cold start. I'll see if I can remember to check that number when it gets cold again, but I'm starting school again and I may forget... But at 1,000 RPM's (when it revvs up during a cold start) I would guess somewhere in the 1-1.5 ball park.

Regards,

Thomas

 

Since the IAC has not been replaced or probably even ever removed and cleaned I would start there. Though it should have been pulled and cleaned when the spider assembly was replaced the dealership may not have done so.

I had to replace the IAC on both my blazer and my S-10 at around 140k or so. One the pintle was not seating properly due to wear and allowing to much air through and the other was very sluggish in making adjustments even after cleaning. I also had to replace the rubber O ring on a friends truck for the IAC as it had crumbled when it was taken out for cleaning.

Try pulling your IAC out and giving both the valve itself a good cleaning as well as the intake area that it seats into. Once both are clean check them for wear. You can also OHM out the valve to check the motor in it. Sorry I don't have the exact procedure and values on hand for that but it is in your Chiltons manual.

If that doesn't do the trick then you may want to start checking vac lines for leaks as well as the gaskets on your upper intake, pcv hose ect... since running lean most often means unmeasured air is entering the system somewhere.

An advanced scantool as TFisher mentioned is a great way to check your fuel usage and fuel adjustments that your computer is making if you can get ahold of one. It can be very helpful in letting you know how bad the problem really is.

If your problem really is that you are running lean you will easily see on the scantool that the computer is adding fuel to the mix when it enters closed loop and starts making air/fuel adjustments. Obviously this will harm your fuel economy but it shouldn't damage anything if you can't find the source of the problem right away. Or decide to wait for a bit warmer weather to stick your head into the engine compartment for a while looking for air leaks.

 

will try to get a hold of a scantool and look into the iac.also is this a difficult repair to attempt to accomplish for a novice. is it easy to get to or do a lot of parts need to be removed to get to the iac. really cant afford a dealer or a garage anymore. i also added seafoam to the gas tank and to the oil to clean things out a bit. how soon do i need to change the oil now. checked the vac lines for leaks and couldnt find any.replaced the grommets as they seemed worn and the pvc valve fits in much tighter. cant hurt for a cheap part.
thanks for answering and offering up the tips. would appreciate any and all tips to get my truck running great with no smoke and better mileage.
again thanks to all and will advise on my iac findings