Excessive cold-start smoke

mazda
smoke

#1

Greetings,



Recently replaced the valve-stem seals, along with the head gasket in hopes that would fix this, but no change.



I need help on this one:

It is my 1985 B2000 that (sometimes) emits Enormous amounts of whitish, lingering smoke on a cold-start, enough to hide a Sherman tank or two.



So far, the best way to avoid the smoke is by Not engaging the auto-choke (not depressing gas pedal at all before starting) and let it warm up, even though it runs roughly for a about 5 mins., and then smooths out, but, with no smoke.

Oil use is less than 1/2Qt per 3K miles.

The smoke does not have the usual oil smell - but not anti freeze either, (only water in system anyway).

And it seems that letting the engine idle a bit Before shutting down helps avoid the smoke…

Problem started about 2 years ago, and after fiddiling with it all this time with no good results I’ve run out of ideas. Tho’ I have considered possibly something maybe coming down a vacuum line…? but have no way to confirm.

Any and all suggestions gratefully appreciated.

TIA… daniel



MAZDA B2000

1985

5-SPD

No Air

160K miles


#2

Stick your index finger (or the finger you like least) into the cold tailpipe. Wear a latex glove if you are intolerant to petroleum. There will be some residue. Your tailpipe is actually a very helpful diagnostice tool. If the residue from the tailpipe is dry and light brown, your engine is working fine. If it is black and sort of dry, but not oily to the touch, the engine is running rich. If the pipe is pouring out steam and dripping water, you probably have a blown head gasket.


#3

Please Tell The Story That Goes With Running “Only Water” In The Cooling System.

Does this truck use any coolant, . . . I mean water ? Do you frequently check the volume of water ? I don’t believe this truck was designed to use water as a coolant. Water boils at 212F degrees (sea-level pressure) .

CSA


#4

You say this has an auto choke, but the 1985 year is right around the time that most manufacturers had adopted fuel injection, though some, especially foreign makes, had troublesome, finicky, computer-controlled carburetors. Which does yours have? It sounds to me like enormous quantities of unburnt fuel are coming out of your tailpipe on a cold start. Could be a carb problem (if equipped), a leaky cold-start injector (if equipped), a bad fuel pressure regulator, or something else??

Is your gas mileage normal, or does this get cruddy mileage?


#5

You are right, this engine SHOULD have water but I have found it useful to only use water right after doing something as major as replacing a head gasket…(Just in case my job leaks I’m not wasting and smearing coolant all over…)
It is a temporary measure until I’m certain it is a sealed system.
I did the head gasket just 45 days back and gave the info about “only using water” so I could eliminate coolant as coming out the tail-pipe (it would smell sweet).
BTW - I mentioned the smoke lingers… and water vapor (steam) usually doesn’t.


#6

Hi,
Yeah, it’s got a carburetor, and it is actually listed as an '86!
And, that carburetor was replaced about 4 years back…

Mileage is EXCELLENT! yup… just took a 3,500 mile round trip to Colorado in August 2010 and averaged 29MPG at 55-60MPH, I can squeeze 22-24 around town. (I’m one of THOSE drivers - putt putt putt)

This Smoke is near white - and LOTS, blows all down the street. Not the Black I usually associated with un-burnt gas (a stuck choke or over-rich), and tapers off to 0 after about 5 minutes- UNLESS (as stated in original post) It decides to NOT smoke at all!!

Thanks for your input… any other ideas?

Well so far it seems no one out there has experienced this problem —
Just took a 1200 mile trip last week with no coolant or oil issues… I kept the “Smoke on Start up” mess to non-existant by Not engaging the choke on cold starts.

So I’m guessing it is pulling the oil somehow thru the vacuum system.