oil burning on startup

[L88 crazy]

I have a 1972 Corvette T top that burns oil for about 1 to 3 minutes upon startup when my dad and I leave it sit and not run the engine for a few weeks. Startup is the only time it ever blows blue smoke. After 3 minutes at the longest, it goes away. I think it possibly needs a head job done. Anybody have ideas?

 

[cruzer99]

Most likely valve guides....do the heads.

 

[Culprit]

And what if I get white smoke instead of blue - and only for about 10 seconds or so upon startup? What does that mean?

The best I can figure is that I'm buring the oil that leaks into the cylinders through bad valve stem seals.



Culprit

 

[Corvette-Pilot]

Most likely valve guides....do the heads.

;stupid

 

[TWINRAY]

;stupid Valve seals. "White" smoke maybe just condensation on a damp cold day?

 

[Bob Chadwick]

Blue smoke oil, black smoke gas and white smoke is usually water. Could simply be condensation blowing out as the hot exhaust hits the cooler air and moisture in the exhaust system.

Are you losing any coolant and does your oil look normal, no milkiness to it?

 

[cntrhub]

.Dried valve guide seals will cause oil puff at start-up. Replace the seals. Here you have two choices. One is...... go to NAPA to the tool section, and get a valve spring removing tool. You will need a compressor, a spark plug hole adaptor and two sets of fresh valve seals. You are going to remove the valve springs and install both intake seals onto the intake and exhaust guides. You will see only one seal on the intake. You will not see a valve seal on the exhaust side. The second valve seal set is used for the exhaust guides. The seal kit comes with a plastic sleeve and you have to use this every time you install the seal, or it will make tiny cuts in the seal when sliding it over the stem. The compressor is to keep constant air pressure inside the cylinder you are working on, so the valves do not fall down inside the cylinder while you R&R (remove and replace) the valve seals.
Second choice..... Remove both heads. Have the head shop R&R the guides, and valves. Install brand new guides, new keepers, new valves (old valve stems worn sliding against the old guides) , seals (of course) and cut the seats in the head. Reinstall the heads.
This will solve your oil smoke on initial start-up.
Check compression before teardown. Check compression after new head work. Do not install the intake manifold just yet. If you have a 15% difference between cylinders, pull the heads and start to rebuild the piston/rings, bore job.

 

[cruzer99]

Have you run the engine long enough to know if you are loosing any coolant? If you do, it would suggest that the engine is sucking coolant into a cylinder which would produce white smoke or steam. You can remove the rad cap and run until the thermostat opens and watch for bubbles. (Bubbles are bad).
Good luck

 

[Culprit]

Maybe what I'm calling white smoke really has a blue tint to it.

I haven't noticed any loss of coolant - but I'll check anyhow. Didn't notice any bubbles while filling my cooling system after flushing the radiator a few months ago.

Since it's only for the first 10 seconds or so after startup, I wouldn't think it would be coolant - I would suspect that I would continue to get smoke/steam as the engine ran and more and more coolant was leaking into the cylinders.

Thanks for the input y'all. I'm leaning toward the valve stem seals.

c5d - I'll take a look at the site.

Semper Fidelis,
Culprit

 

[rpounds]

Valve guides . . .

The good news is, if you have good compression, they can be changed without yanking the heads . . . .

 

[lobes290]

I have just noticed that mine does this too. Blueish white smoke right on startup then goes away quickly. Im planning to rebuild or get a crate within the next few years. Is it ok to wait that long or should i start looking into it over the winter?

 

[cntrhub]

lobes290,
Run it till three things happen:
1. You didn't top off the oil religiously, and the engine siezed from burning off all the oil taken from the crankcase.
2. It's so bad now, you are replacing more spark plugs than filling the gas tank with gallons of gas.
3. You were pulled over by the police for smoking mosquito larva without a permit.
Remember, that when the intake sucks in air, it will suck oil through the guides also. Subtle oil loss while running, but burning off oil none the less. You may not see the oil being burned while driving, but it is there happening.
Here is the above verification of bad guides....... Drive the car on a flat road, or down a long hill. Simply lift on the throttle and coast for awhile. Look in the rear view mirror and punch the throttle, or have a friend drive behind you and follow you to monitor the oil puff. You will see a bellow of smoke as you throttle away. This is the oil being sucked into the cylinder and being burned off. Check oil level almost daily if it's a daily driver.
If you constantly see oil smoking as you drive, this is piston ring damage/wear.