White smoke

S

ScottLESABRE400(66)

Member
Hey,
I have white smoke coming from left tail pipe , 340 4bbl rebuilt about 8yrs ago. I've had this problem for about a year or so. I haven't noticed any overheating and there is no visible sign of water in the oil. Dose anyone have any idea what the white smoke could be from. I have yrt to pull a plug.

Thanks
 
There is a good chance that it is a head gasket and if it is, you should surface the head while it is off.
Forums have suffered from things like Facebook :( Personally I prefer forums.
 
White smoke on startup engine cold is normal, along with water dripping and puddling out of the exhaust pipe. The water is good indicator of proper stochiometric mixture. If the white smoke is coming out when engine is hot, that sounds to me like a combustion leak, heads, blown head gaskets, etc.
You can test for combustion leak by using a chamber kit with the blue test solution on top of radiator neck or expansion tank.
Can you elaborate on your compression test results?

I agree, sometimes I see a tumbleweed rolling by on this site.
 
GL03 said:
White smoke on startup engine cold is normal, along with water dripping and puddling out of the exhaust pipe. The water is good indicator of proper stochiometric mixture. If the white smoke is coming out when engine is hot, that sounds to me like a combustion leak, heads, blown head gaskets, etc.
You can test for combustion leak by using a chamber kit with the blue test solution on top of radiator neck or expansion tank.
Can you elaborate on your compression test results?

I agree, sometimes I see a tumbleweed rolling by on this site.
Click to expand...
Left bank: #8=95 #6=155 #4=155 #8=180.
I stopped there.
 
ScottLESABRE400(66) said:
#8 went up to 120 with a little oil added in.
Click to expand...
I believe that this test indicates the rings to the cylinder wall have poor seal. Needs rings along with other work in this area. Another leak could be at the valves. Usually the exhaust valves take the wear more so than the intake. I think possibly the smoke you are seeing might be from this bank.
Due to the variance in cylinder pressures, it is my opinion that your engine needs work overall.

If you can, do the heads. Test the valves by filling the intake and or exhaust chambers with fuel and looking on quench side, should not leak through. A little seepage no biggie, but after the valve job no seepage right away, after more than 10 minutes no worry.

Then you need to make an assessment on the rings and decide if you will hone and ring or do more. You use an inner diameter bore caliper, take crisscross measurements to see for egg shape cylinder. if symmetric more of a candidate for just honing and ring replacement.

If your main bearings have worn excessively, should check crank for out of round. otherwise you could get noises from the bottom after rebuild.
 
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I think it is a valve problem. The heads were not done when motor was rebuilt. I do recall white smoke and ruff start that cleared shortly after rebuild.
The absence of water in the oil would rule out problem with the head seal. I'm wondering if a top end adjustment would help.
The smoke from the left bank has just about cleared up again. It has been less humid and warmer.
I thank you for the help. Glad I got on the forum.
Purchased a new compression tester as I'm not sure about the accuracy of the one I used last week.
Another thing to consider is fuel octane. I've been running 93 pretty much since I got the car.
May want to boost that.
Scott
 
I think it is a valve problem. The heads were not done when motor was rebuilt. I do recall white smoke and ruff start that cleared shortly after rebuild.
The absence of water in the oil would rule out problem with the head seal. I'm wondering if a top end adjustment would help.
The smoke from the left bank has just about cleared up again. It has been less humid and warmer.
I thank you for the help. Glad I got on the forum.
Purchased a new compression tester as I'm not sure about the accuracy of the one I used last week.
Another thing to consider is fuel octane. I've been running 93 pretty much since I got the car.
May want to boost that.
Dc
GL03 said:
I believe that this test indicates the rings to the cylinder wall have poor seal. Needs rings along with other work in this area. Another leak could be at the valves. Usually the exhaust valves take the wear more so than the intake. I think possibly the smoke you are seeing might be from this bank.
Due to the variance in cylinder pressures, it is my opinion that your engine needs work overall.

If you can, do the heads. Test the valves by filling the intake and or exhaust chambers with fuel and looking on quench side, should not leak through. A little seepage no biggie, but after the valve job no seepage right away, after more than 10 minutes no worry.

Then you need to make an assessment on the rings and decide if you will hone and ring or do more. You use an inner diameter bore caliper, take crisscross measurements to see for egg shape cylinder. if symmetric more of a candidate for just honing and ring replacement.

If your main bearings have worn excessively, should check crank for out of round. otherwise you could get noises from the bottom after rebuild.
Click to expand...
Just did a compression test, very pleased with the results. Old tester NG. 190 to 200 every cylinder except #2 . it was 180 psi . At this point the motor was starting to cool down. Actually great numbers. Still most likely have a valve issue.
Whats your take on lead additives?
Thanks again
 
With the price of fuel from Bidenomics I would just spend on something that will give me real returns in comfort or performance. The exhaust valves get exposed to very hot temperatures. Usually, you would replace all the exhaust valves at a head job, but some of us do to lack of money or availability of parts may just clean them up. Another thing is the there is three angle cuts in the head, which most people don't consider at that time of the repair. I will add that a little light porting can clean up casting bits in the passages. The sad thing is that unless you do it yourself most shops won't give it this much attention, just too fast of money-making industry.
 
GL03 said:
With the price of fuel from Bidenomics I would just spend on something that will give me real returns in comfort or performance. The exhaust valves get exposed to very hot temperatures. Usually, you would replace all the exhaust valves at a head job, but some of us do to lack of money or availability of parts may just clean them up. Another thing is the there is three angle cuts in the head, which most people don't consider at that time of the repair. I will add that a little light porting can clean up casting bits in the passages. The sad thing is that unless you do it yourself most shops won't give it this much attention, just too fast of money-making industry.
Click to expand...
As most I have a lot on plate, love the Buick but drive it rarely. That was actually the 2nd autozone Compression tester that failed me. I do plan to get the heads ported some day.
 
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