Blue Smoke on startup, what does it mean?

Question

I own a 1987 Chevy Custom Deluxe with 4.3 Liter engine with Throttle Body Injection, When it has been setting for awhile or overnight it has blue smoke that comes from the tailpipe when I start it up. What does this mean?

Answer 1

I'm going to agree and disagree with people on this question. The valve guides are worn, and that is common for most vehicles. It is not a major issue as long as you do not over-rev the engine before it warms up...and that you frequently check the oil (engines with bad guides tend to use a little more oil) Once the engine warms up...ususally 2-3 minutes the seals are tight and away you go. I used to have an 86' mazda b2000 that had bad valve guides from 200k miles of driving, and during the winter cold it would smoke for 2-3 minutes, then you could tell when the engine warmed up because...it quit knocking and rattling and sounded like a kitten. Chevrolet engines are like that, they will run wounded and puking as long as you keep oil in them. The major thing I would worry about if I were you would be the main bearings in the engine...they tend to leak on older chevy's after age and drip oil on the driveway and out of the case...If special attention is not kept on oil levels you could cause some damage....

Answer 2

blue smoke at start up is a good indication that you have bad valve stem seals around the valves.Not a major problem.If it has over a hundred thousand miles you might just want to keep driving.If you find a good mechanic he can replace the seals without removing the heads. I have done many a engines like that.All you will need is a set of valve stem seals and set of valve cover gaskets.The cost should be around 200 to 300 for this repair depending on were you have repaired.One other thing it could be is the cylinder head drain holes could be clogged and not allowing the oil to return to the oil pan fast enough..Once you remove the valve covers you can determine if this is your problem.On this engine there is a hole in the very front corner of the head and the same place on the rear.If it is due to sludge clean the cylinder head area open all drain holes change you oil once reassembled and change your filter.Change oil on a shorter interval. Piston rings worn will cause you to smoke all the time.Your problem is worn valve seals a common problem

Answer 3

blue smoke is oil getting into the cylinders. There are only three paths for this.

Past the rings because the piston rings and cylinder walls are worn out.

past the valve stems because the stems, valve guides and valve seals are worn and leaky.

Into the intake from the crankcase vent system.

Almost all of these indicate a rebuild is due. The valve stem seals are the easiest and cheapest attempt to fix, but your rings are likely worn also. Worn rings usually produce enough blow-by to force oil mist into the intake past the positive crankcase ventilation system.
You have choices.
Drive till it drops. (damn the envirinment)
Sell it off. (nasty)
Scrap it out ( loses money)
Have the motor rebuilt or swap it out with a good one. ( 4.3 is more expensive than a V8)
You can try an oil treatment hoping that it will actually do what it says on the can.(good luck on that)
good luck. the motor will likely last many more miles, with luck.

I suggest both a pressure and vacumn test to see if you can define the likely cause better.
How much do you think it is worth to keep a now 20 year old vehicle. If the rest of the mechanical and body is good you might want to rebuild.

Answer 4

If just at start up then you have bad valve seals.
Dose the engine run well other then that? do you foul spark plugs?
you could maybe get by with valve seals and they can be installed without removing the cylinder head.
If you are low on money and need a fix you could add a oil supplement to your crank case oil and temporarily stop or slow the process until you get back on your feet.

Answer 5

Problem with early production Altima with 2.5 liter motors is there is not much that can be done cheaply to correct oil consumption issues. Not many mechanics will want to put pistons and piston rings into a high mileage motor and stand behind all the work. New Motor will cost with a new cat converter over $5,000 then you will have to worry about the transmission. Add some oil treatment and sell that car soon.

Answer 6

This is a very common problem with the 4.3 liter engine. Its your valve guide seals. I had the same problem on my 1989 Chevy Astro van with that same engine. Mine started puffing blue smoke when it only had about 30,000 miles on it. I mentioned it to the parts man at the Chevy dealership and he told me that it was a real common problem on these engines but upgraded seals were available to correct it. He said with the labor it would cost about 600 dollars to fix but it wouldn't hurt anything to drive it like it is which is what I have done. I don't have to add any oil between oil changes so its not much oil being burned. I have 278,000 miles on it now and it runs just fine. Check your oil before you change it and if it isn't low I wouldn't worry about it.

Answer 7

Leaky valve guides are a common problem with Chevrolet engines. I had an '85 IROC that puffed blue smoke from the right bank at start-up with less than 30k on it...

This problem is so prevalent that they've devised this little devise in lieu of a valve job-

http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?lang=-1&catalogId=10002&storeId=10001&categoryId=29698&searchItemId=110475

You remove the rocker arm and put the "umbrella" over the valve stem. It completely covers the spring and seals against the head. Replace the rocker arm. No more smokey smoke at start-up!

Answer 8

oil leaking past the valve guide seals twenty year old cars do that! Amount of oil the engine uses is critical. One qt every 1,000 miles might be a problem run out of oil between oil changes.

Answer 9

The oil is leaking past the valve stem seals and down along the valve guides back down into the cylinders .When you start it up it is that oil that is burning out of the cylinders,after its been driven awhile that will clear up.until you stop and let it set again.

Answer 10

If it's not using alot of oil between oil changes, then it's the valve seals. You can leave it or fix it, not urgent. I've seen it happen in newer cars with as little as 20k miles.