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Kohler K161 Diagnosis Regarding Smoke


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#1 TGaffney OFFLINE  

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Posted October 21, 2012 - 08:43 PM

Kohler K161 – Diagnosis regarding White Smoke

I recently started reviving a 1959 Bolen’s Ride A Matic that was my father’s. I believe the engine is original to the tractor, which was in storage for at least 10 years before I started working on it. The exterior of the engine was covered in black oil, and the oil in the engine was jet black and thin. I power washed the tractor, changed the oil, put in new a plug/points/condenser and reset the timing. After some tinkering I got the engine running pretty smoothly. The engine idled well, ran under load fine, and did not smoke at all. Compression was at 120 but leaked out fairly quickly.

I noticed oil was coming out of the area where the block meets the head so I replaced the head gasket and flattened the head which was warped. Since installing the new gasket and flattening the head, the tractor has run very poorly. The engine will only run at idle and under load if the choke is half open and even then the engine is running very rough. There is also a lot of whitish smoke coming out of the muffler and if you are by the tractor while it is running for any length of time your clothes end up smelling like exhaust. Compression is still at 120 and leaks down, but not as quickly as it did before the new head gasket and cylinder head flattening. I checked the timing with a light and it is still set correctly

My guess is that the rings are bad and that the oil which was formerly leaking out of the warped head is now being burned – which I’m guessing would cause the white smoke. But if that is the case, would the burning oil cause the engine to run rough, and also cause the situation where the choke needs to be half open?

If the rings are letting a lot of oil pass is there anything I could try prior to putting in new rings and possibly boring out the block at the same time?

Any other possible cause that anyone can think of?

Thanks - Tom

#2 MH81 ONLINE  

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Posted October 21, 2012 - 08:51 PM

A good way to tell if it's rings or valves is to do a compression test, then add a tablespoon of 30 wt into the spark plug hole. Usually if the compression goes up, it's rings... if not, it's valves.
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#3 Guest_gravely-power_*

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Posted October 21, 2012 - 09:25 PM

Clean the crankcase vent and make sure it is reassembled correctly. This may solve your problem as far as smoke goes.
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#4 boyscout862 OFFLINE  

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Posted October 21, 2012 - 09:56 PM

What was the condition of the cylinder when you had it apart? Did you do anything with the valves? Could something have gotten in the gas? Old stuff in the tank or the carb may have taken a while to dissolve and is now causing problems. The choke having to be half on usually indicates dirt in a carb passage. Or could gas have gotten in the oil? If there is no contamination, try cleaning and readjusting the carb.

When ever the head is taken off a kohler or briggs engine its a good idea to check the valve lash(gap). This effects the valve timing. I usually lap the valves first for a more accurate measurement.

If everything points to the rings being the problem its a good chance that they are stuck in the piston ring groves. I have had good luck with Marvel Mystery Oil(MMO) for decarboning cylinders and pistons. Add a teaspoon of MMO to a gallon of gas in the tank and run the engine. When the engine is hot shut it down and pour a tablespoon of MMO in through the sparkplug hole and let it sit for a couple of days. Then run it for awhile and readjust the carb. This has worked on many engines for me, from 2 hp B&S to an OHC6 in a 69 Firebird. I put MMO in all my gas tanks(cars and tractors) and it seems to keep them running well.

Good luck and let us know how it goes.

Edited by boyscout862, October 21, 2012 - 10:25 PM.

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#5 JDBrian OFFLINE  

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Posted October 22, 2012 - 10:38 AM

Have you checked the quality of the spark. A weak spark will cause the engine to run poorly. I had a similar problem with a 14hp k321. It was running rough and nasty at low speed then suddenly would not start at all. It turned out the points were out of adjustment. With the points properly adjusted it ran much better.
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#6 TGaffney OFFLINE  

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Posted October 22, 2012 - 09:08 PM

Thanks to everyone for their ideas and suggestions.

MH81 - I did add a bit of oil through the spark plug hole when I was checking the compression - the reading went up about 5 PSI. Is that enough of a change to suggest a ring issue?

Gravely-Power - I'll clean and check the crankcase vent against what is shown in the Kohler manual - I need to read up on how it is supposed to be. I'll post the results after I do that.

Boyscout 682 - The original tank was really full of dried crud so I have been using a new clean tank and fresh gas. It is possible that some fuel mixed with the oil as I think the float was stuck a few times as I had gas leaking out the tube running from the carb back to the oil bath air filter. I'm going to change out the oil and see if that helps. When I had the head off there was some carbon build up which I cleaned off. I didn't do anything with the valves as I need to study up on how to address those. I only worked on valves once and it was 15 years ago or so. If changing the oil doesn't help I'll try yout Marvel Mystery Oil tip and see how that goes.

JD Brian - Weak spark is certainly a possibility. I have a spark plug tester and the spark intensity seems to be inconsistent. I think the new points are gapped correctly as the timing mark is right on "SP" when using a timing light. I've been thinking about getting a new magneto to rule that out. The original bendix magneto has a cracked case and the ohm readings are high (like in the millions) instead of the 3 - 7 thousand Ohm range I've read it is supposed to be.

I'll check back in a couple of days and post what my progress has been.

Edited by TGaffney, October 22, 2012 - 09:12 PM.


#7 MH81 OFFLINE  

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Posted October 22, 2012 - 10:20 PM

Thanks to everyone for their ideas and suggestions.

MH81 - I did add a bit of oil through the spark plug hole when I was checking the compression - the reading went up about 5 PSI. Is that enough of a change to suggest a ring issue?


It's not really bad. Does it leak down slower than it did before?
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#8 JDBrian ONLINE  

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Posted October 23, 2012 - 05:06 AM

Thanks to everyone for their ideas and suggestions.

MH81 - I did add a bit of oil through the spark plug hole when I was checking the compression - the reading went up about 5 PSI. Is that enough of a change to suggest a ring issue?

Gravely-Power - I'll clean and check the crankcase vent against what is shown in the Kohler manual - I need to read up on how it is supposed to be. I'll post the results after I do that.

Boyscout 682 - The original tank was really full of dried crud so I have been using a new clean tank and fresh gas. It is possible that some fuel mixed with the oil as I think the float was stuck a few times as I had gas leaking out the tube running from the carb back to the oil bath air filter. I'm going to change out the oil and see if that helps. When I had the head off there was some carbon build up which I cleaned off. I didn't do anything with the valves as I need to study up on how to address those. I only worked on valves once and it was 15 years ago or so. If changing the oil doesn't help I'll try yout Marvel Mystery Oil tip and see how that goes.

JD Brian - Weak spark is certainly a possibility. I have a spark plug tester and the spark intensity seems to be inconsistent. I think the new points are gapped correctly as the timing mark is right on "SP" when using a timing light. I've been thinking about getting a new magneto to rule that out. The original bendix magneto has a cracked case and the ohm readings are high (like in the millions) instead of the 3 - 7 thousand Ohm range I've read it is supposed to be.

I'll check back in a couple of days and post what my progress has been.


If your coil is bad then that could be your peoblem or at least part of it. Unfortunately there are often multiple problems in these older engines and they will run with these problems until something gives up entirely. If your coil is cracked and reading a high resistance I'd say you should find another one to try.
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#9 TGaffney OFFLINE  

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Posted October 24, 2012 - 09:20 PM

MH 81 - the rate of leak down after the new head gasket & flattened head seemed just a bit slower. I didn't notice any difference in the rate of leak down between the dry and wet compression tests.

JD Brian - I think I am going to try out a replacement magneto that was suggested from a supplier out of Connecticut. I was tinkering with the engine today and I noted that my spark at the correct gap of 0.025 is almost invisible on my spark tester and the tractor did not fire off at all. With the gap closed to about 0.010 the spark was bright orange and the tractor fired off well. Would it be reasonable to assume that the electrical charge is to weak to make it strongly across the 0.025 gap?

Gravely Power - I took off my carburetor to clean it in Pine Sole and I took apart an cleaned the crankcase vent. Not sure what I was supposed to look for there - it seemed to be intact so I cleaned and reassembled it.

When I put the carburetor back on and fire up the tractor I'll post how it goes.

Tom

Edited by TGaffney, October 24, 2012 - 09:23 PM.

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#10 boyscout862 OFFLINE  

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Posted October 24, 2012 - 09:44 PM

The plug gap should be 0.025 and the spark should be strong and blue. Your measurements of resistance make the magneto very suspect. Since it does work somewhat I'd suspect all parts of the system. Clean all grounds. Check them with a multimeter. Before replacing the magneto, clean the magnets in the flywheel and check the magneto leg gaps. Check the points, points wires, and condenser with an ohm meter.

Magnetos are expensive so check everything else carefully first. Your new coil will be happier with everything cleanned and checked before it is installed.

I'm interested to learn how the Pine Sol worked on the carburator. I'm trying vinegar on one of mine. Good Luck
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#11 TGaffney OFFLINE  

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Posted November 05, 2012 - 06:47 PM

Update on my K161 efforts.

I cleaned the carburetor with pine sol which seemed to work pretty well and put in a new float, needle, gaskets, etc. I adjusted the float settings to the measurements prescribed in the manual for the engine. I also set the carb needles to the initial set up specs and it fired right up and ran well. I then drained the almost new oil and put in brand new oil and added 20% lucas heavy duty oil stabilizer. I also added a bit of marvel mystery oil to the cylinder through the spark plug opening (hoping to free potentially stuck rings)

When I started the tractor again the next day it smoked like crazy - which I'm guessing was initally due to the marvel oil burning off. I then adjusted the needles and idle setting - though I should have just left them as it ran best on the suggested intitial settings - which I have reset several times but unfortunately haven't been to duplicate. The engine is still putting out billowing white/gray smoke for a minute at start up on idle and then after that it burns off. I get little blasts of black smoke when I accelerate hard. I also get the occassional afterfire and I get a pretty reliable after fire if I decelerate hard. I've adjusted the needles to make sure it is not running to rich and I'm at the point where it stumbles if I lean out the hi speed or low speed a quarter of a turn - so I think I'm not setting it to rich. I've pulled the plug a few times an looked at it and it is blackish/oilyish.

I'm guessing there is unburned fuel from the potential weak spark issue so I need to check the connections and other electrical items as suggested by boyscout 862. This would explain the afterfires - but what is the cause of the billowing smoke at startup? I'm thinking I will get a fuel shut off and run the gas dry and then fire it up again to rule out/in the possibility of the carb leaking fuel into the oil.

Also - last night I noted a light sheen of oil on my cooling fins below the cyinder head gasket - so I'm thinking I may have blown that while messing with the engine and causing afterfires while I was trying to lean out the carb.

Any other suggestions as to what could be causing the smoking at startup?

Thanks for your input!

#12 ol' stonebreaker OFFLINE  

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Posted November 06, 2012 - 09:05 AM

With the compression you have I'm wanting to point a finger at the oil ring. The 15 HP B&S in my Poulan does the same thing, but judging by the piston slap I hear it's due for a new piston and rings. I haven't checked compression because it has the comp release. I guess I could turn it backwards w/ a drill.
Mike

#13 TGaffney OFFLINE  

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Posted November 19, 2012 - 11:35 PM

I purchased a new magneto and replaced my original to see if that would help with the possible unburned fuel issue I was apparently having.

Other than being able to run with the plug gapped to the correct specs, I didn't see/hear much improvment in starting or overall engine performance. I then replaced the points/condensor with a NOVA II electronic ignition module. I think the engine actually started easier on the points - but with the NOVA II it seems a bit more stable. I checked the timing after the change and it was slightly advanced (maybe 2 degrees?) with the NOVA where before I changed to the NOVA II it was slightly retarded (1 degree or so).

I also changed the head gasket today as I had partiually blown one and compression went from 60 up to 90 with the change - but again I noted no significant change in engne performance.

Here is a video of the smoke coming out when I rev it up from idle. Does this seem normal/acceptable?

I need to post some video of what it is like at first startup. Lots of smoke!

Also - do the tappets / valves sound unususlly load to anyone?

PS - I got a message saying I coundn't upload this kind of file - so there is no video.

#14 ol' stonebreaker OFFLINE  

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Posted November 20, 2012 - 12:18 AM

Is the smoke black or blue? If you can't tell for sure take it out in the sunlight.
Mike

#15 boyscout862 OFFLINE  

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Posted November 20, 2012 - 07:19 AM

If it is running good enough to use but is smoking, run it. I have found numerous times that running an old engine with Marvel Mystery Oil mixed in the gas( 1/2oz per gal) would stop smoking after a month of use. This went for lawn mowers to my big truck. Good Luck




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