Board index The Technical stuff Ask your Mechanical Questions here Parked on small grade and smoked

Parked on small grade and smoked

All Models and Years

Unread post Sat May 25, 2013 9:53 pm

Posts: 1094
Location: Norfolk, VA

If the valve seals are shot, it will usually smoke all the time. When it smokes at startup then clears, it's usually oil sneaking around the rings as it sits.
Click it!

Unread post Sun May 26, 2013 6:18 am

Posts: 7
Happened to me too. Bluish smoke is in Carbs flooded. It clears up after all is regulated once more...remember always keep the butt up in the air! :my02:

Unread post Sun May 26, 2013 6:33 am
bbodie52 User avatar
Corvair of the Month
Corvair of the Month

Posts: 5948
Location: Lake Chatuge - Hayesville, North Carolina

I thought black smoke is gas -- the rich, sooty unburned fuel. Bluish smoke was supposed to indicate oil burning in the combustion chamber -- as with oil getting past the valve stem seals and guides, or oil bleeding past the piston oil control rings.

ASE A1 Engine Repair Certification Practice Test wrote:
Q: A vehicle briefly blows bluish/gray smoke from the tailpipe only when first started in the morning. The most likely cause of this condition is:

A: A leaking valve seal will cause oil to leak into the cylinders chamber over time, usually overnight.

Exhaust Color Diagnosis

Blue/Gray Smoke: Blue/gray exhaust smoke is an indication of oil burning in the combustion chamber. These are possible symptoms and causes:

Valve Seals: Leaking valve seals will cause blue/gray smoke at startup because oil leaks past the seals into the cylinder after the engine shut down.

Valve Guides: Excessive clearance between the valve stem and the valve guide allows oil to leak past the gap into the cylinder.

Piston Rings: Worn or damaged piston rings will cause blow-by resulting in blue/gray smoke.

Worn Cylinder Walls: Worn cylinder walls cause blow-by resulting in blue/gray smoke.

PCV System: A stuck closed PCV valve will cause excessive crankcase pressure resulting in blue/gray smoke.

Black Smoke: Black exhaust smoke is an indication of rich fuel condition. These are possible causes:

Fuel Injectors: A leaking or dripping fuel injector will cause a rich fuel condition.

Fuel Pressure Regulator: A stuck closed fuel pressure regulator will cause a rich fuel condition.

Fuel Return: A restricted fuel return line will cause a rich fuel condition.

White/Gray Smoke: White exhaust smoke is an indication that coolant is burning in the combustion chamber (if you see this, you are not driving an air-cooled Corvair) ::-): . These are possible causes:

Cylinder Head: A crack in the cylinder head (around the coolant jacket) will cause coolant to enter the combustion chamber.

Engine Block: A crack in the deck of an engine block near the coolant jacket will cause coolant to enter the combustion chamber.

Head Gasket: A damaged or blown head gasket will cause coolant to enter the combustion chamber resulting in white/gray smoke coming from the tailpipe.

The Corvair Aircraft Engine Crowd wrote:
CorvAircraft> Valve Stem Seals

Rad Davis rad_davis at
Mon Apr 11 18:18:12 PDT 2011

Mark has correctly identified the reason that valve stem seals are used on Corvair cars. Simply put, they keep oil from oozing into the intake and exhaust ports when the car is parked on an incline and oil pools in the downhill rocker box.

You get a light blue puff at startup from oil down the exhaust valve stems. In extreme cases, enough oil down the intake valve stems can cause misfire due to fouled plugs on startup.

There is also the concern that car engine spend a lot of time at idle and light loads (high intake manifold vacuum), and some wear on the intake valve stems can result in a lot of oil being pulled down the intake valve stems and result in heavy restrictive carbon deposits on intake valve heads. I've seen engines like this - it does indeed happen with a granny drive cycle, bad seals, and some valve guide wear.

On the other side of the argument you have the simple fact that a tight clearance between valve and guide needs regular lubrication or it will become loose, and the stated purpose of a valve stem seal is to restrict oil flow into this space. It's a particular concern on the exhaust valves, which run much hotter and don't have the consistent strong difference in pressure to pull oil down the valve stem and keep them lubricated and cooled.

For a car, probably the ideal thing to do is break the engine in with no seals, then fit them to the intakes after break-in if you don't anticipate thrashing it enough to keep carbon off the valves. On an airplane, I can't imagine why one would run seals at all, for precisely the reason Mark mentions. In any event, there's no reason to use exhaust stem seals ever - all they prevent is a momentary puff of blue smoke on startup.

I don't call the Corvair engine the 'blue smoke six' for nothing. Accept this part of its character and be grateful it's not a radial or a two-stroke.

- Rad Davis

On 4/11/2011 7:00 AM, Mark Langford wrote:
Rodger Nicolls wrote:

Should I use the Viton valve stem seals on only the intakes or on the exhausts also?

I think conventional wisdom on aircraft engines is don't use them at all on either valve. I've never put any on my engines, and I don't "use" oil or blow it all over the place either, so apparently that works. Aircraft engines don't experience that high vacuum situation that you'd get with a car going downhill with the throttle shut, so it's not a problem in our usage. I left them off my first engine because of my VW experience...they'd just melt off and you find them in the sump at the first oil change. Conversations with William Wynne verified my belief that they were unnecessary. I cherish my valves and valve guides, and wouldn't mind a bit if they stayed better lubricated anyway...

Mark Langford



Weight: 0 lbs 2 oz
Catalog Pages(s): 6,17(5)
Price: $ 15.05



Weight: 0 lbs 2 oz
Catalog Pages(s): 6,17(5)
Price: $ 11.15


FROM CORVAIR UNDERGROUND - Left-click with mouse to enlarge the image...
Corvair Underground Valve Components Catalog Page.jpg
Corvair Underground Valve Components Catalog Page
Brad Bodie
Lake Chatuge, North Carolina

Unread post Sun May 26, 2013 9:15 pm

Posts: 207
Location: Las Cruces, New Mexico
As always thanks Brad! And everyone else. the thing is the car didn't smoke today. those scenerios don't match my situation. When it smokes is intermittently and I wouldn't make a big deal about it except when it did it quite a bit of smoke and then smoked only a bit going down the road. durring these spells if i put my foot in it it would "act up" more. I purposely picked a nice spot in the mountains this weekend friday so i could see how she did when pulling a long hill with a good grade. No problem and no smoke but interestingly it did smoke ealierer in the day when we went to the grociery store to pick up pick-nic supplies. It doesn't smoke on start up. Only intermittently in town and is exacerabted when i put my foot in it. but again it didn't do it today at all. I am thinking about the PCV valve and checking it (wondering what one would soak it in to clean it)but i haven't and I haven't put a compression check on it either. it almost seems like there is oil in the gas but the only additive I ever use is Marvel mystery oil and i haven't done that lately. Its kind of wierd but i suspect that what ever it is is going to get worse (its just a feeling). i wonder if the longer trip actually blew some kind of buuild up out. The only problem with that theory is that to be honest the puffing is more than a puff its a opretty big cloud of definately blue smoke so I think "blowing" it out would be less smoke (maybe I am wrong here). If its the rings-and according to the suppied document-it would tend to do it on start up so i am a bit puzzeled. Once I have the time to focus on it i should be able to tell rather easily i assume. I will keep you posted. Thanks again.
1964 Monza Corvair

Unread post Mon May 27, 2013 1:18 am

Posts: 877
A similar thing happened with my Morris recently, I found that the valve oil seal had lifted off its seat (the top of the valve guide) and was moving up and down the valve stem, it would occasionally re-seat, only to dislodge again. In my case the valve guides were also worn so I'm thinking the lateral movement of the valves in the worn guides dislodged the seal . I would be interested to know how this repair can be done without removing the head, as a previous poster suggested, as the valve springs need to be removed to fit the seals, this require access to the head of the valve for the valve spring compressor tool to work, I have used tools that work through the spark plug hole ( Ford pinto) but find them a poor substitute

Unread post Tue May 28, 2013 7:14 am
UNSAFE User avatar
Corvair of the Year
Corvair of the Year

Posts: 2008
Blue smoke generally indicates oil burning.

My guess is that when the car is parked on an incline the oil pools at the low end of the head and is sucked thru a
failing seal or guide and causes the smoke at start-up.
;lk;lkl;k;k;o.jpg (25.09 KiB) Viewed 997 times
Kevin Willson
1965 Monza 3.1
Juneau Alaska

Unread post Thu May 30, 2013 8:51 pm

Posts: 207
Location: Las Cruces, New Mexico
Kev, it doesn't do it at start up and it hasn't done it for two days now! :banghead:
1964 Monza Corvair

Unread post Fri May 31, 2013 5:51 am

Posts: 189
Location: Monte Vista, Colorado, USA
davemotohead wrote:
I park on flat ground,,has not happend to me in a million miles! :neener:

Dave, your ground may be level, But something else may not be! :neener:
Richard Cutter
Monte Vista, Colorado

1960 700 Sedan / 1964 Spyder, Conv. / 1964 Monza Sedan
“Truth is Treason in the Empire of Lies.” -George Orwell

Unread post Fri May 31, 2013 11:17 am

Posts: 207
Location: Las Cruces, New Mexico
very true, Mountain Man! I guess it shouldn't bother me. I actually put some Marvel comics magic mystery oil in it a couple of days ago for kicks and grins and it still hasn't smoked. I am not going to complain. I am going to drive it to garage sales this weekend.
1964 Monza Corvair


Return to Ask your Mechanical Questions here