Newbie here... Just inherited a 1990 Mazda B2200.. Been in the family since new and well cared for... I got it after the head gasket left loose at 314,000 miles.. When I got the truck I had the head resurfaced and pressure checked, installed new valve stem seals, head gasket and timing belt..I also flushed the cooling system and installeda new thermostat... Runs like a top!!! But when left sit for at least 3 hours or more is smokes like a banchee on startup... It'll continue to smoke for about 15 or so mins then pretty much clear up.. Compression is good, no overheat or bubbles in the cooling system.. DOesn;t seem to be loosing any coolant or oil.. I replaced the valve stem seals a second time thinging I may have buggerd one up or something but still it smokes.. When the gasket blew it did get hot, twice in fact.. The first time when it initially blew, and a second time when they thought it wasjust a thermostat, replaced it, and tried it out.. Before the head gasket it did smoke slightly but only for maybe 30 seconds after startup.... Typical of old valve stem seals...Just wanted to see if I'm on the right track in thinking that the rings got cooked one the over heats...

 

I should also add, the smoke is white... I'd swear it's coolant... But I never loose any, and the cooling system holds hot or cold up to 20psi... Just to completely ruel out the coolant angle I took it out, warmed it up till it stopped smokeing...Pulled the lower hose off then shut the engine off, and left all teh coolant drain.. Fired it up the next morn for about a min with no coolant.. And there was smoke... The cats make it hard to tell by smell, but it almost smells like an engine that has tranny fluid burning in it.. (like when a transmission vac modulator blows).. I have checked out the choke and it seems to be operating as it should.. No fuel drips int he carb when I shut the engine off.. When the white smoke clears I get puffs of black when I punch it from idle.. No shame for a carb that hasn;t been touched in over 300,000 miles....

Thanks!

 

Hey Max, and Welcome!!
It sounds like you know you"re stuff and have tried everything I might"ve, and more.

Howis your brake fluid level?Could your brake booster have sprung a leak and be drawing brake fluid into the engine?
Is there excessive moisture build up on the bottom of the oil fill cap? Y'know, I"m sure. That disgusting, nastymilkybrownish colored stuff?

 

Thanks... Been wrenching for way too many years... And after having several VW diesels you learn to check EVERYTHING at least 3 times....

I had the valve cover offthe other night, squeaky clean.. And the oil that normally remains laying on the head after the engine is shut offdidn't mysteriously dissappear either (thought that might leak me to a crack or somthing)... Good call on the brake fluid!!!! I've put about 500 miles on it and it still stops, but I'llgive that a look.. Never even gave that a thought...

The thing that isdriving me batty on this is that it stops smoking after 10-15 mins of running.. Until then it billows out enough smoke to make 3 cars behind me go away... Been debating about punching the cats and see if the smoke clearsoutta thereany faster... THey are probably shot anyhow...

I guess I hadn;t mentioned that it is a 5 speed and a 2bbl carb.. So no, it can;t be the trans modulator......[8D]

 

I saw that happen once where the booster went bad and the vacuum was pulling fluid out past the seals in the master sending it directly into the intake.I don't remember if there was smoke or not, or what color it might have been.

 

Never ran into it personally but I have heard of that happening.. Rare but at this pointit was worth the check... I just ran out to look.. Unfortunately the fluid is still nice and full..[:@]

I've been debating whether it could be a crack of some sort in an obscure place.. Maybe something that closes up after everything heats up....

I had a Mazda protege in the shop a few years ago (1.5 DOHC)that was EXACTLY the same way...Never was over heated or anything but the owner wanted the head redone to fix the problem... After the rebuilt head was on it still did it.... Ultimately he ran it low on oil and put a rod through the blockthen put a low milage boneyard engine in the thing.. That fixed his right up....

 

Hmmm... Interesting. A family trait? Nahh. Not that I"m aware of.
You did say the engine overheated, but not that you had the block decked... 'Course that's a tremndous amount of work to do if it turns out not to need it too.

 

White smoke says coolant to me as well.

You may want to try running some Ceramic Engine sealant. Some are compatible with anti-freeze, some aren't. This link is the anti-freeze compatible type. I've seen this stuff seal up some fairly decent cracks in cylinder heads (on high performance engines.)

http://store.summitracing.com/partde...p;autoview=sku

 

These two vehicles are the only two I've run into this on... I think it's just a fluke that they were both Mazdas though. If I rmeber correctly the Protege did continue to smoke somewhat even after it was warmed up... Been too long to remeber for sure...

The truck was indeed overheated.. Twice in fact, although not quite as severely the second time... I did not have the block decked.. I did check it over with the straight edge and feeler gauge and it seemed okay. I noticed no VISABLE cracks. If I remeber correctly Mazda uses a pretty high nickel casting for their blocks which makes them pretty rebust..
The machine shop I use is extemely thorough and extremely picky about what can and can't be fixed as far as taking a chance on something working that is questionable... But I have this gut feeling that there it almost has to be somthing with the head itself...For now I'm dealing with the smoke and wating to see whathappens and hoping in the mean time that someone may have run into the same thing and can ad least give some insight on where to look....

 

Yeah that wasmy though, until it still did it with no coolant in it...I got it warmed up one evening with the cap off the radiator so it didn;t build pressure..Ran it till the smoke cleared, Shut her down, drained the coolant and left it sit over night... Started it the next morning with the cooling system dry, left it run for about 2 mins and it smoked just as always...

Gonna try punching the cats in the next night or two.. Then I can get a better idea of smell and color..I did find out that the front cat is original, but the rear one was replaced with an aftermarket of some sort.. I know some those generic cats will burn up about anything you put through them.. Including oil..... Been checking coolant daily and it hasn't lost any as of yet... Plugs show no signs of anything unusual... I have a bottle of that block sealer here.. I'm not ruling it out, but I'd like to be completely sure it's coolant...