8N engine smoke

Hi all, it has been a long time. My father purchased what we believe to be a 1949 8N with a 2/9N hood with the intake stack sticking out of the hood and a 2/9N front axle with 2/9N front hubs. The serial number on the engine along with the rest of the tractor, transmission, rear axle, etc point to it being a 1949. It is still a 6V tractor. The engine seems to start well and runs well, with good oil pressure, but she smokes like crazy out the tailpipe and oil breather tube, which I believe indicated bad rings. Is this correct? What should our next steps be? Compression check dry and wet and then possibly ATF soak?

Hiney.......ALL engines "smoke". Yes, do a dry compression test FIRST. N-Engine specs is 90psi minimum; new engines are about 125psi. Only do a "wet" test iff'n dry is below 90psi. Pour about 1-oz (teaspoon) down the sparkie hole and test again. Use at least 6-rumpas fer each test. Iff'n wet test is still below 90psi, then an ATF soak would be in order. Remember, after a "wet" test yer engine will SMOKE!!!

ALL 9N/2N's have 3-speed trannys and weird 4-nipple dizzys. 8N's have 4-speed trannys. ........smokeless Dell

How much if any smoke is coming out of the oil tube (blow-by). I had smoke and blow by real bad it had set on blocks for 6 yrs. I had only 30 to 35 on dry compression. I took olds advice on the filling it ATF soak 3 times and also ran ATF in the gas. The ATF soaks and in the gas made wonderful smoke screens. I got the compression to 90+ on all 4 cyl. It starts and run good now. Check with old.

My 'Ol smokey' (2N) smokes and burns oil like crazy. Have to
clean the plugs after about 3 to 4 gallows of fuel. Starts with 40
pounds oil pressure and maintain at least 35 while brush
hogging. Unless it starts running low of oil. I've put every
additive known to tractors. Stays the same. been like that for
years.
Some day I'll go thru it. But it's running for now.
Here's the last compression test I ran on it:


DRY WET

#1 110 120

#2 70 90

#3 60 80

#4 110 120

Mine was buring oil pretty bad. Didn't mess around with test just pulled the head. Wound up doing a rebuild.

Rick

The next step is to run a compression test. Post back with your readings. Remember to do it on a warm engine with the airstream not going through the breather element with throttle open. Compression tests require adequate engine RPM to be valid. Remember also compression can be acceptable with an oil burner due to stuck oil control rings. Gerard

We did the compression test on the smoker tonight.

DRY. WET
#1. ~120
#2. ~115
#3. ~90. 100
#4. ~95

We didn't do the wet test on the other cylinders per Dell's instructions. Cylinder #3 was really close to 90psi, so we did the wet test. Cylinder #3 showed oil around the spark plug hole and threads when we took the spark plugs out to do the compressin check. So does this point to stuck oil control rings and should we do the ATF soak?

(reply to post at 04:44:39 04/03/13)

Click to expand...

You need to do a cylinder leakage test... If you don't know what that is Google it...

Hobo,

Thanks for the reply. I have Googled, the cylinder leak test and have a couple of questions. Forgive me if these questions seem simple or elementary, this is the first time I have really tired to diagnosis such an issue. I understand the cylinder leak test requires you to pressurize the cylinder at TDC with compressed air and see how much and where the cylinder is leaking air at, be it the intake, exhaust, rings, or head gasket, etc. What I am struggling to make the connection with is for in this case when the compression test showed all cylinders were within spec, what new information will this test provide me in regards to the reason that the engine is followed by a large cloud of blue smoke? Can the compression rings be sealing allowing for good compression results but the oil rings not sealing and allowing the oil into the cylinders, thus the blue cloud of smoke? But if this is the case, how would the blue smoke be coming out of the oil filler tube as well as the exhaust?

Hiney

(quoted from post at 10:07:24 04/03/13) Hobo,

Thanks for the reply. I have Googled, the cylinder leak test and have a couple of questions. Forgive me if these questions seem simple or elementary, this is the first time I have really tired to diagnosis such an issue. I understand the cylinder leak test requires you to pressurize the cylinder at TDC with compressed air and see how much and where the cylinder is leaking air at, be it the intake, exhaust, rings, or head gasket, etc. What I am struggling to make the connection with is for in this case when the compression test showed all cylinders were within spec, what new information will this test provide me in regards to the reason that the engine is followed by a large cloud of blue smoke? Can the compression rings be sealing allowing for good compression results but the oil rings not sealing and allowing the oil into the cylinders, thus the blue cloud of smoke? But if this is the case, how would the blue smoke be coming out of the oil filler tube as well as the exhaust?

Hiney

Click to expand...

If i could add my 2 cents...

You have answered your own question. Piston rings wear. In your case oil rings cannot hold the oil, compression rings don't seal properly, thus oil is drawn into combustion chamber hence the blue smoke from exhaust. Cumbustion byproducts are forced past the compression ring and into the crank case, thus smoke from the filer neck.

By adding oil during your wet test you have helped seal the compression ring and got higher numbers. That was expected. The only thing a leaked down test wil also show if you are leaking at the valves. Air out of carb,leaking intake valve. Airout exhaust, leak at exhaust valve.

(quoted from post at 21:07:24 04/03/13) Hobo,

Thanks for the reply. I have Googled, the cylinder leak test and have a couple of questions. Forgive me if these questions seem simple or elementary, this is the first time I have really tired to diagnosis such an issue. I understand the cylinder leak test requires you to pressurize the cylinder at TDC with compressed air and see how much and where the cylinder is leaking air at, be it the intake, exhaust, rings, or head gasket, etc. What I am struggling to make the connection with is for in this case when the compression test showed all cylinders were within spec, what new information will this test provide me in regards to the reason that the engine is followed by a large cloud of blue smoke? Can the compression rings be sealing allowing for good compression results but the oil rings not sealing and allowing the oil into the cylinders, thus the blue cloud of smoke? But if this is the case, how would the blue smoke be coming out of the oil filler tube as well as the exhaust?

Hiney

Click to expand...

No all of them are not in spec...3&4 are low not in spec (if they were why is 1&2 so high/normal) were's the loss at... A leak down test will help determine were the loss is... You and most get caught up with the advertised min. spec,,, if all were 90/95 you would assume all were evenly worn but why are 3&4 so far off...

Lets say it was ran hot and scored the rings,pistons and walls all the cyl. had 90 would you assume cuzz you had min spec's it would be OK to move on with life...

A leak down will tell ya were the compression loss is it will not tell much about the oil control rings but that can not be determined yet... So why are 3&4 so far off... Read on about cylinder leakage... 20% is the line drawn for severely worn engine if all the valves seal and show no valve leakage... If you use 115 as a # for a engine in top notch condition and divide it by 10 you get 11.5,,,, 11.5 X 2 = 93 so I would consider a 93 compression number if all the valves seal to be a severely worn engine that has something to do with the rings, pistons are cylinder walls... You will have to de a leakage test to figger this out... NO ONE can tell you by a compression test alone why 3&4 are so far off other than a guess....

Hobo,

Thank you for your explanation. I appreciate the kindness of individuals on this forum to help people out and explain things, even if they might seem elementary. We will do the cylinder leakage test and see what those results show and go from there. Thanks again.

Hiney