Why do I "sometimes" blow smoke at start up

[Shewster]

I can't find a specific pattern. Cold, hot, etc. But sometimes when I start my '72 Std it will puff out some smoke during start up. It's random. The engine starts and runs fine. Just a little embarrassing when it does it.

Any ideas of the source?
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'72 Bug, One-family car, 350k happy miles (ok, a few of those miles were not so happy)

[Bertie1969]

Assuming the smoke is blue then it's likely to be oil getting into a cylinder after the engine has stopped. It could be you have a worn valve guide and the randomness may be because the engine doesn't always stop in the same position.

If the engine stops with the valve in the worn guide open, then oil can settle on the valve stem and run into the cylinder - it only takes a small amount to give a cloud of smoke.

If this is the problem you may be able to see which cylinder is affected by checking the spark plug colour, if it's a very small amount of oil it may not show on the plug.

[djkeev]

White Smoke......
Blue Smoke........
Black Smoke.......

All different causes and remedies.

AC VW...... For the most part White Smoke is unlikely, though with those crappy chrome air filters letting in rain water...........

Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[Mr.Duncan]

Mine does the same thing.

and its a rebuilt engine with 800 miles on it

Brand new heads!

Randomly VERY random it will put out a puff cloud of smoke.


I kinda like it.
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[HRVW]

With a new rebuilt (P & Cyls) could be the oil ring is not set above the 3 or 9 o'clock mark......maybe the rings were not "off" set properly on installation.

[Shewster]

Good questions and ideas. I would call it BLUE smoke.
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'72 Bug, One-family car, 350k happy miles (ok, a few of those miles were not so happy)

[camaroboi13]

There's no two ways to put it...it's just oil getting past the valves or the pistons and burning up on startup. I honestly wouldn't worry about it until you start seeing it all the time. Most of the little Honda kids I see have blue smoke all the time...but that's what happens when you live your life around 7000rpm
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[djkeev]

Blue smoke is oil burning.

As mentioned, a puff on start up is of no concern to me. If you start using a quart or two between oil changes you've got something to be concerned about.

My 74, with a bone stock 73 1600 in it, will puff some blue smoke on start up. The longer it sits between uses, the bigger the puff.

I " rebuilt" the engine, new bearings, ground crank, cleaned oil passages, new oil cooler and new rings on used pistons and used honed cylinders.
The heads only got a good cleaning and valves lapped in, the guides weren't noticeably loose.

The engine doesn't have many miles on it. I rebuilt it three years ago and then drove it only slightly before I moved it into the shop for almost two years while I fixed the body rust and painted the car.

The most it's ever driven is this Summer and even at that its only for pleasure, jaunts for ice cream or a moderate drive on a Summer evening.

The odometer doesn't work but I'd guess I haven't put but 300 miles total on this engine. The rings may not even be seated in yet.

I KNOW that the ring gap orientation was correct on assembly so that isn't a concern of mine, most / many rings rotate around the piston as the engine runs anyway so ring orientation is really a moot point.

Bottom line.......
I don't worry about it! It's a 38 year old car! If people want to point and laugh at my little puff........ Let them!

Let them also realize that they don't have such a cool car of their own! Maybe they mock you in jealousy?

I have probably lost more oil from my loose oil pressure sender unit or weeping oil pan gaskets than I ever burned!

Relax! The car IS old enough to legally smoke!

Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[Shewster]

[pwmcguire]

I find mine smokes blue when my oil is just a little over full.

[camaroboi13]

[zombiebug]

Every blue moon mine gives a nice puff. Usually only when the car doesnt fire on its first or second crank. I'd give you a color if I could see it. All in all, im not worried. As long as she purrs nicely and isnt smoking constantly im happy.
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'74 Super

[72Bettie]

A puff of smoke a start up is nothing to worry about. I would be more worried if you have smoke all the time. Also make sure you don't have too much oil in. I found my 72 likes to live halfway between the hash marks on the dipstick (exactly 2.5 quarts) for me.

[modok]

Have you ever seen a radial airplane engine start
There is a tendency for the bottom cylinders to get full of oil, due to, gravity.

The flat four, with it's horizontal cylinders, has a tendency to do this "sometimes". Frankly I'm surprised they don't do it more often. Does it mean something??? hmm, it can mean your rings aren't perfect, but as I often say about rings...... how they seal with the engine running is really the main concern, so your ok

[doublecanister]

how about after a long drive, say 35-40miles at speeds of 55 to 60-65,
let it set for 3 hrs
smoks on startup, sometimes have to floor it to start.

My 73' THING with 1600 started doing this recently very intermittant.

only once did i notice it low on oil after a long drive in the mountains.

seems to run ok but as far as the smoke color,
Ive never seen blue smoke, must be my eyes as it looks white
to white gray to me, but smells like burnt oil.

after driving it home, let it set maybe 10min no smoke to start and put in gargage.

I figure I'd get a compression tester and give the engine a check, re do the tune up, valves, timing, points, carb adjust it's been a while but we dont drive it ever day either.

any suggestions there?
Thanks
T

PS: i posted in here instead of the THING forum, not finding much there. Thought you guys could help.
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73'- Thing
66' -Mustang GT- Fastback
51'- Ford F1 pickup Flathead V8

[jlex]

May also depend on the viscosity/type of oil you're using. If using 10W30, try switching to 30W to see if things change. Pure synthetic, if used, may be sneaking by the rings as well...
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jlex.
'70 std. "Elsie"
'88 Carrera

[Joey]

[birddog1]

[doublecanister]

You know, I did change recently or i should say I added a quart of the quakerstage "defy" 10w/30 as it's "supposed' to contain a bit more zinc/phosphorus for wear prevention.

i've run 10w/30, 30w, and 15w/40 before, usually with a bit of STP oil treatment for wear prevention and a tad of Marvel Mystery oil. (just a bit).

Not going to swear to it but the defy quaker oil could be part synthetic.

I figure I'd do a tune up this weekend, valves, timing, carb, points, check clean n gap the spark plugs and do an oil change if time permits all that.

Thanks for the suggestions!
I'll monitor it and see if it continues after the oil change.
T
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73'- Thing
66' -Mustang GT- Fastback
51'- Ford F1 pickup Flathead V8

[mouser98]

my rebuild has about 500 miles on it and it does the blue smoke thing about every other startup.