My engine smokes,how can I tell if its the valve seals,Im pretty sure its not the rings,I hope its not,any suggestions would be helpful,Thanks,leave ans. on forum or email me at shootemup56yahoo.com Its a 1984 coupe with a 350 eng.that is what I was told.dont know that much on engines,Ive done all the interior over looks nice,please help me with smoke,Ive heard nothing but good reports on the people on this forum helping out their comrads in need,I hope you can help me .

 

What color is the smoke? The color will tell us whether it's oil or coolant.

Does it only happen after the car has sat over-night then, once started, only smokes for a short while then stops?

Is the smoke coming out of the muffler(s)?

Jake

West Point ROCKS!

 

Hi Jake Its white smoke and it smokes all the time I havent run it that much its not on the road it comes from the exhaust,it starts alittle after I start it up I havent let it run more than 20 min,or so any ideas.

 

White smoke from the exhasut is usually from coolant or water getting in the cylinder producing steam. Has this happened more than once? I had a blown head gasket a couple years back on mine.

Has it overheated? I would start by checking the coolant level to see if it's low. Have you had to refill the coolant recently? Also check the oil and see if it is a milky color. Depending on how that turns out you can check your coolant system pressure or have an oil sample sent off to test for traces of coolant in the oil. http://www.blackstone-labs.com/ If it was me I would not run it until it's solved.


FYI

Blue smoke from the exhaust is usually oil burned in the cylinders.
Black smoke from the exhasut is usually too much fuel in the cylinder, rich condition.

 

Have someone ride behind you and get up to speed then give it gas and then let off coast w/o disengaging the clutch,do it a couple times,If your friend behind you sees smoke when giving it throttle after decelerating it's the rings. If it just smokes when you crank it up it's more likely the valve guides.

 

Yep, I agree with Rick. White smoke tells me coolant. Go to AutoZone and rent (it's free) their coolant system pressure tester. Screw it on, pump up the pressure to no more than 20 psi and see if it holds the pressure.

If not, you can be sure you have a leak. It could be the intake manifold gasket or, more likely, a leaking head gasket. Seems there have been a rash of failed head gaskets lately.

Either way, it'll be time to break out the tools.

Let us know what you find.

Jake

West Point ROCKS!

 

JMO...............

I would do a compression test on all 8 cylinders. That will end all this guessing on what it might be. Good luck!

Corvette Mike

 

What we're doing is not guessing; it's called diagnosis; diagnosis to find the cause of white smoke to come out of the exhaust as the main symptom.

A coolant system pressure tester is a diagnostic tool.

Same thing a doctor does. The procedure is simple: When you go to the doctor, he asks about your complaint, what you're there for. He then runs some basic tests, like blood pressure, listens to your heart, checks your temperature, pulse, etc. These tests are designed to help in the diagnosis.

Based on the test results and the patient's complaint (symptoms) he knows which avenue to pursue; where to focus his diagnostic effort. If you are complaining about chest pains, he won't start by looking at your feet.

The poster's complaint (symptom) is that he has white smoke coming out of the exhaust. Most of us know to identify white smoke out of the exhaust as being caused by coolant somehow entering the combustion process.

In order for coolant to be present in the combustion process it has to come from the cooling system which, when operating normally, is isolated from the remainder of the engine's systems. So, somehow coolant is leaving its isolated system and entering the combustion process.

The most logical thing to do is to look for a leak somewhere in the cooling system. A leaking hose, leaving a puddle under the car or intake manifold, won't cause smoke out of the exhaust. The leak has to be internal. To check for that you pressurize the coolant system and, if there's a drop in pressure, you then KNOW you have an internal leak.

Now, the problem becomes identifying from where the leak is occurring. There are only a few places that could cause coolant to enter the combustion process.

A cracked head or block, and/or a leaking intake or head gasket are the most common. Absent any other symptom, (like the engine has recently over-heated badly), gasket failure is the most likely cause, so the smart move would be to diagnose for that. Always check the easiest to do and possible cause first.

Doing compression test won't isolate the cause. A low reading on one or more cylinders found in a leak down test could be caused by the piston ring(s), excessive piston to wall, leaking valve(s) and maybe some others I can't think of right now.

BTW, conducting a compression test on one of our engines is easier said than done, do to the cramped engine compartment space. It also requires specialized tools that many of us don't readily have at hand. including a compressor and special fittings. On top of that the results will be inconclusive.

Check using the easiest to do and most probable cause first

Bottom line, conduct tests for the most probable cause first. Tests like checking the oil dip stick for signs of coolant in the oil, draining the oil from the pan, etc. However, the pressure test is by far the easiest, quickest test to do and costs nothing to run.

If not found there, then move on to other diagnostic tests, which we can recommend after getting the pressure holding results.

My money's on a gasket, partially because it's such a common occurrence. It shows up on virtually all the Forums I visit.

Jake

West Point ROCKS!

 

Jake.

JMO................. Blown head gaskets are diagnosed with compression tester too.

Blown head gaskets on vettes will smell of coolent, and drip out the pipes.

Valve seals can also be checked by compression test also, as well as rings.

 

Thanks everyone for your suggesstions,I will start with checking for coolant in the oil and do a coolant pressure test and than I will get back to you,thanks so much,I hope its just a head gasket,like I said its my first vette and Ive always wanted one,Im 58 and finally got one,hope I can solve this problem,I would love to put it on the road.

 

Just so you don't feel like the Lone Ranger, there are at least two other guys on other Forums, LS1.Tech and another one I can't recall right now, who are experiencing the exact same thing right now. White smoke out of the exhaust.

So it's a fairly common occurrence, even in later model engines.

After you located the source and want to repair it yourself, if you need advice on the repair procedure, just post here and we'll help you.

Jake

West Point ROCKS!

 

Good Luck..I know your on the rightt track

Cajun