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Kohler dieseling at shutdown

Started by ScottInCabot, November 26, 2015, 06:44:35 PM

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ScottInCabot

I've already called a talked to a tech(sorry, forgot the fellas name).

My newly purchased WMLT28 w/Kohler 19hp has a 'farting problem'(hey, that's what my wife calls it).  I allow the engine to idle to the lowest rpm and when I turn the key off, she will backfire every time...or worse, it engine diesels.

The tech asked if what type fuel I used.  I informed him unleaded 91 octane(non-ethanol).  He said that was 'good'.
The tech asked if the engine was idled all the way down.  I informed him that it was.  He said that was 'good'.

I questioned him to whether anyone else has had issues. He stated only if ethanol type fuels were used or the idle was to high when the key was turned off.



So....what now?  I'm not a small engine mechanic, and I don't want to be one.  I do not mind changing oil or fuel filters, cleaning air filters(or replacing as needed), and making sure 'things are tight and in functioning condition'.  This motor has approximately 22hrs, and I think it shouldn't have this problem....


What needs to be done to fix it?  Please....advise.






Scott in Cabot
Timber framing RULES!

starmac

I have to wonder if the low idle is not set right. It is always timing or fuel, and I doubt it has any timing adjustment on that engine.
Old LT40HD, old log truck, old MM forklift, and several huskies.

hamish

What model and spec is your engine?

Most likely your engine is equipped with a anti-after fire/fuel stop solenoid.  Look for a long cylindrical housing securing the fuel bowl onto the carb.  If so you need to shut the engine off at when the throttle is at 1/2 to full throttle.
Norwood ML26, Jonsered 2152, Husqvarna 353, 346,555,372,576

bkaimwood

Most popular causes of symptoms listed are...
1-idle speed set to high
2-fuel shutoff solenoid not functioning properly
3-higher than normal engine or combustion chamber temps...typically caused by excessive carbon build up, poor engine cooling, or lean fuel mixture...in your case, the first 2 causes of high temp most likely don't apply
4-improper ignition timing
-note that carbon in cylinders absorbs fuel, and stays hot once heated, sitting there like a hot coal...so when you turn the key off, the spark plug stops sparking, but the engine tries to continue running on this auxiliary fire source...overall high engine temps can do the same...lean fuel mixtures also can have the same impacts, increasing combustion chamber temps...just sayin'...good luck!!
bk

submarinesailor

We had the same problem until we started allowing the motor to cool down for several minutes after cutting.  We believe that the motor gets quite hot while the motor is pulling thru a cut.  So after finishing a log or large cut, we let it idle for several minutes before we turn it off: for the next log, a break or the end of the day.  This has helped a lot.  We get very little popping/backfiring/farting from the motor when we do this.

Bruce

snowshoveler

At the service schools, Kohler has been all over the map on this sort of thing.
The muffler is still very hot when you shut off the engine and as it coasts to a stop its still pumping fuel through the engine.
When the right mix builds up in the muffler ...ka blooie. Some engines will just about scare the crap out of you when this happens.
Best results for most but not all folks is to bring the engine down to half throttle for a minute or so before shutting it off.
Remember these are a fan cooled motor and the fan has to be going fast enough to do its job.
A lot of new engines don't even have an idle circuit or control on them.
Regards Chris
International T5 dozer
JD M tractor
MF skidloader
Jonsered chainmill
Vintage Belsaw

tyb525

I've had the same problem with a 20 horse lawnmower engine. It will always backfire if you shut it off too soon. If I let it idle for a couples minutes, no backfire.
LT10G10, Stihl 038 Magnum, many woodworking tools. Currently a farm service applicator, trying to find time to saw!

sawguy21

snowshoveler has it. You are getting an after fire, as the engine spools down with no spark the ignition has been shut off, raw fuel/air mix is sucked through and meets up with a hot muffler. Back fire through the carburetor is a whole 'nother problem usually related to ignition issues.
old age and treachery will always overcome youth and enthusiasm

bkaimwood

The last few posts have good information...but a few things are still concerning. A muffler that running too hot and igniting fuel after shutdown certainly would explain the backfire concern. But would likely not explain the run on/dieseling, if, in fact, that's also going on. If the exhaust system is hot enough to act as an ignition system, and causes this, in my opinion, there is still a problem, or at the least, a design flaw. Other fellas have said that allowing the engine to idle for a brief period before shutting it down prevents it. That's good that there's a "fix", but not really. If I had spent that kind of money on a mill, and was told I had to allow cooldown idle for a while before shutdown, I wouldn't like that answer. The muffler ignition may be the cause of the ignition, but not the root problem. This support one of the things I listed earlier, engine running too hot, and supporting ignition after the engine is shut down. Why? I am kind of leaning toward the lean fuel mixture under these circumstances. Mostly because its a newer, low hour engine. As mentioned, many of newer engines, no matter who made them, are a hair lean, due to emissions. This makes everything run warmer than it would if the mixture was right, or a hair richer. When my exmark kohler engine runs on in the heat of the summer, it a sign that, well, its hot... idling for a brief moment does prevent it. But its not the fix or the cause. It tells me its time to clean and adjust the carb, cause its lean, if the idle speed is ok. I clean and adjust the carb, and its good for another 2 years. One may think that richening the fuel mixture may cause this, or make it worse, due to the extra fuel. This is not so... remember where the fuel is at, and how much is not the problem in this scenario, its where the source of ignition is coming from. If this is the case, I would check and/or adjust the fuel mixture to manufacturer specs...if the screws are where they are supposed to be, I would pull and check the spark plug color. Then richen the mixture slowly, run the engine under normal operating conditions, and recheck the plug. Keep doing this until the plug has the right color on it.
bk

47sawdust

My Craftsman mower has a 14hp Kohler.It will backfire every time I shut it off with the key.If I let it idle down,pull out the choke,and turn the key it never backfires.
Mick
1997 WM Lt30 1999 WM twin blade edger Kubota L3750 Tajfun winchGood Health Work is my hobby.

millwright

I installed a tiny tach on my 25 , the idle was too high from factory. A simple adjustment took care of the problem

ScottInCabot

Thanks everyone for your inputs.

> I usually allow quite a bit of time to allow the engine to 'sit and idle'....not sure what amount of time has passed, but it's usually 30-45 seconds.  If waiting longer will help, I can find something more to do while waiting...
> Hot exhaust...I can see that causing an issue.  Not sure how to overcome that problem, even idling for a 'while' will still keep hot gases in it.  Would a larger exhaust cure the issue?
> Dieseling......that isn't an issue of fuel in the exhaust.  And the occurrences, while not written down at time of incident, 'seem' to be getting closer together(this is just my observations from running the mill-happens once during one job, twice during next, four times during the latest job.....) and I would only guess(again, I'm not a small engine mechanic) that this doesn't help increase the life of an engine.
----How do I get this issue fixed?



And how many other WM LT28 w/19horse operators are having this occur?




Scott in Cabot
Timber framing RULES!

Ox

How about turning the gas valve off while running and let the engine suck the carburetor bowl dry?  No fuel, no ignition, no "farting".  It's good to this for winter storage anyway.  I'm sure you'll be able to time it just right after a few tries and get it to the point that you can plan ahead of time and have it running out of gas very soon after your last cut.
K.I.S.S. - Keep It Simple Stupid
Use it up, wear it out, make it do or do without
1989 GMC 3500 4x4 diesel dump and plow truck, 1964 Oliver 1600 Industrial with Parsons loader and backhoe, 1986 Zetor 5211, Cat's Claw sharpener, single tooth setter, homemade Linn Lumber 1900 style mill, old tools

Don_Papenburg

But killing a hot engine is still not a good thing , I would let it idle for a minute or so then shut down the fuel .   That should be done by the fuel solenoid on the carb. check that for proper operation.
Frick saw mill  '58   820 John Deere power. Diamond T trucks

LeeB

This is not a new problem with Kohlers. The 15 hp Kohler I had on my TK 1200 14 or 15 years ago did the same thing.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

drobertson

Quote from: LeeB on November 27, 2015, 11:46:50 AM
This is not a new problem with Kohlers. The 15 hp Kohler I had on my TK 1200 14 or 15 years ago did the same thing.
I was going to say the same,, I had a 19.5 hp, mower, did the same, at times, letting it cool down helped.  I have a Briggs 6.5 on the tiller, maybe 10 years old, or more, it does it too, idling down and letting it run for a spell help.  I still hate to hear it or have to wait.  It should be addressed, just not sure how to go about it.
only have a few chain saws I'm not suppose to use, but will at times, one dog Dolly, pretty good dog, just not sure what for yet,  working on getting the gardening back in order, and kinda thinking on maybe a small bbq bizz,  thinking about it,

tyb525

I have heard/read from various sources that letting any engine idle for a minute or two before shutdown is better for it, especially after running it hard. A good design shouldn't backfire or afterfire after shutdown though, as long as you didn't cut the ignition at full rpms.
LT10G10, Stihl 038 Magnum, many woodworking tools. Currently a farm service applicator, trying to find time to saw!

Kbeitz

It's new engine design problems. I collect old garden tractors. I would always run the engine halt throttle or less to do my work. Try that with the new stuff and you have problems. Newer tractors the engine is really closed in and don't have room to breath. The newer engines need to run wide open to keep somewhat cool.
To meet the stiffer smog laws they lean out the gas and take away the carb adjustment.
Most of the time there is no fix.
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Dave Shepard

Cool down is a good idea with any engine. It has nothing to do with his much one paid for their mill. If you don't cool down a hot turbo diesel, you will eventually have bigger problems than backfiring. It's just part of good machinery operating.
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

ScottInCabot

OX.....while I'd love to 'store' the mill for winter, oh wait....we don't really have much of a winter in central Arkansas!  Few days below freezing, maybe a few flurries(up to about 3" at most-and it melts the next day or two)....  I'll be milling through the winter....it's easier on me not doing a lot of milling in the summer anyway ;)

Dave Shepard......'turbo diesel'?  This is a gas motor....



I can live with the 'farting'....it's the dieseling that has me more concerned about engine life.

Scott in Cabot
Timber framing RULES!

Verticaltrx

I have an LT15 with the new 19hp Kohler and it has on occasion dieseled. The fix is to let the motor cool down properly before shutting it off. 30-40 seconds isn't enough, I let mine idle/cool down a good minute or two (sometimes more if I've really been pulling it hard) and haven't had any dieseling or backfires since.


As others have stated, this should be common operating practice for any equipment.
Wood-Mizer LT15G19

tnsnakebite

2006 TimberKing 1220 20 H.P. Kohler. Trailer kit and 2 extensions. Purchase date 10-2015. Price-$3,300
J.D. 1070 w/loader

Dave Shepard

Quote from: ScottInCabot on November 27, 2015, 07:16:58 PM
OX.....while I'd love to 'store' the mill for winter, oh wait....we don't really have much of a winter in central Arkansas!  Few days below freezing, maybe a few flurries(up to about 3" at most-and it melts the next day or two)....  I'll be milling through the winter....it's easier on me not doing a lot of milling in the summer anyway ;)

Dave Shepard......'turbo diesel'?  This is a gas motor....



I can live with the 'farting'....it's the dieseling that has me more concerned about engine life.

Scott in Cabot

My point was that idling an engine down is just part of the process of running equipment. Just because someone bought a new mill doesn't obviate the need for proper operation, as bkaimwood seemed to be suggesting.
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

ScottInCabot

Quote from: Dave Shepard on November 27, 2015, 10:02:26 PM
Quote from: ScottInCabot on November 27, 2015, 07:16:58 PM
OX.....while I'd love to 'store' the mill for winter, oh wait....we don't really have much of a winter in central Arkansas!  Few days below freezing, maybe a few flurries(up to about 3" at most-and it melts the next day or two)....  I'll be milling through the winter....it's easier on me not doing a lot of milling in the summer anyway ;)

Dave Shepard......'turbo diesel'?  This is a gas motor....



I can live with the 'farting'....it's the dieseling that has me more concerned about engine life.

Scott in Cabot

My point was that idling an engine down is just part of the process of running equipment. Just because someone bought a new mill doesn't obviate the need for proper operation, as bkaimwood seemed to be suggesting.


And once again...."turbo diesel"?
But I guess you're too busy 'attacking me'???  Wow!

Please block me or ignore me there Dave, I'm not in the mood for your drama.....




Scott in Cabot
Timber framing RULES!

LeeB

I don't think anyone was attacking you Scott. The man was simply saying that any engine including turbo diesels need to cool down before killing them. A turbo won't backfire if you don't cool it down but will soon enough suffer the consequences the same as a gas engine would.  Attacks around here are few and far between. This is just not that kind of forum.  :)
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Jeff

Hardly a personal attack. Maybe a little drama on your end is all I see. Since you reported this Scott, I'm answering it.
Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

Chuck White

Welcome to the Forestry Forum, tnsnakebite.
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

ScottInCabot

Quote from: LeeB on November 27, 2015, 11:06:33 PM
I don't think anyone was attacking you Scott. The man was simply saying that any engine including turbo diesels need to cool down before killing them. A turbo won't backfire if you don't cool it down but will soon enough suffer the consequences the same as a gas engine would.  Attacks around here are few and far between. This is just not that kind of forum.  :)


Fair enough.....was a long day, and since it's impossible to convey 'intent' on anything where typing is concerned....apologies from me please.



Question for the 'group'.
In your manual(I've read it to great lengths), exactly how long does the 'manual' say to let engine idle before turning it off?

-Mine states-  quoted from manual word-for-word
QuoteLet the engine run for 15 seconds with no load, then turn the key switch to the OFF position.

I wait much longer then that, although I have never used a stop watch....carrying flitches and boards, stacking, and such probably take longer then 30-45 seconds?  On a side note, the little B&S 10horse I had on the LT10 never backfired, and I'd often shut it down really fast.

As I said before.....humbly, I'm not as concerned with the 'farting', if it were backfiring through the carb(it'd be different).  The dieseling, to me is the problem.  Was just wanting to find out from other LT28 owners with this engine configuration if this was also an issue from them....





Scott in Cabot
Timber framing RULES!

terrifictimbersllc

Not every single comment in a thread is always directed to the original poster.

The 30HP Kohler gas engine on my Peterson will backfire loudly almost all  of the time, and run backwards occasionally a bit too, if I hit the kill switch at full RPM.  If I push the throttle down and wait several seconds before killing it, there is mostly no backfire and no running backwards.
DJ Hoover, Terrific Timbers LLC,  Mystic CT Woodmizer Million Board Foot Club member. 2019 LT70 Super Wide 55 Yanmar,  LogRite fetching arch, WM BMS250 sharpener/BMT250 setter.  2001 F350 7.3L PSD 6 spd manual ZF 4x4 Crew Cab Long Bed

Dave Shepard

I'm not attacking anyone. It can be hard to convey an idea over the internet, especially when being so limited by trying to do it over a smart phone. If you think that I'm attacking, you are mistaken. If I was critical of anyone, it was bkaimwood, and the thought that buying a new piece of equipment had anything to do with the best operating practices. All manufacturers are faced with the difficulty of less than ideal fuel properties and spa regs. If idling is necessary to prevent this issue, then so be it.


Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Jim_Rogers

bkaimwood:
In post #8 you said: "check for the right color". but for us non mechanics that isn't the best advice unless you tell us what the right color is, or what the wrong color is. I don't know either of them, and would find it helpful if you would tell us the colors you are talking about. Thanks, this is just asking for more information to understand how things are suppose to run.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

snowshoveler

If I read it right, the mill is still "new" and will require many more hours of use to break in.
It is getting hot because its still stiff and will get better with time.
The cool down period will help and you will learn what makes the engine happy.
The dieseling/run on is just because its hot.
I know you said you go out of your way to make sure you are buying non ethanol fuel, and most of us try to avoid it.
However if you just buy a gallon or so at a time you end up with whatever the customer before you bought.
I never knew this until it was pointed out to me at a service school.
The gas pump is usually some distance from the gas nozzle and that's where the change over takes place.
Just something to make note of.
Regards Chris
International T5 dozer
JD M tractor
MF skidloader
Jonsered chainmill
Vintage Belsaw

POSTON WIDEHEAD

Its all good Scott. They ride me like a rented Mule.  >:(
The older I get I wish my body could Re-Gen.

Kbeitz

Spark plugs should run a light tan.
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

LeeB

You can't ride a goat. Sometimes you can train them to pull a wagon though.  Just don't get too close to them when they start 'backfiring'.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Jim_Rogers

Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

bkaimwood

Jim R...happy someone read in detail, and took in what I wrote... Kbeitz beat me too it...tan, light brown OK...clean, too lean, black, too rich. I mean this respectfully to all, but it bothers me, so I hafta say...the cause/causes of this concern has already been listed here... Despite this useful information, why still focus on how long it has to idle before shut down in order to have it shut down as it should, without having to mask a concern? It is true and good practice to let any engine just off heavy load to return to idle, and settle down idling before shut down...but we shouldn't have to worry about whether or not it will actually shut off, or scare the dog into a heart attack...there should be no need for a timer. Every concern has a remedy...
bk

Kbeitz

Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

bkaimwood

Can always count on you, Kbeitz, for the detailed pics...I prefer to see a strong #11, but not a #10...IMO, a 12 is OK on a liquid cooled engine, but would prefer not to see that lean on air cooled...
bk

booman

Try shutting it down at about 1/2 throttle.  The  newer engines should have a solenoid that shuts of the gas to the high speed jet on shutdown.   This works on my LT15 with the 25 hp Kohler and my riding lawnmower with a 27 hp Kawasaki.
2019 LT15G25WIDE, 2013 LT35HDG25, Stihl MS880 with 59" bar with Alaskan sawmill attachment.  John Deere 5045 tractor with forks, bucket and grapple.  Many chainsaws.

bkaimwood

Quote from: booman on November 29, 2015, 01:55:28 PM
Try shutting it down at about 1/2 throttle.  The  newer engines should have a solenoid that shuts of the gas to the high speed jet on shutdown.   This works on my LT15 with the 25 hp Kohler and my riding lawnmower with a 27 hp Kawasaki.
You're killing me...
bk

tnsnakebite

booman is spot on with this. Read your Kohler manual.
2006 TimberKing 1220 20 H.P. Kohler. Trailer kit and 2 extensions. Purchase date 10-2015. Price-$3,300
J.D. 1070 w/loader

Chuck White

Welcome to the Forestry Forum, booman.

My mill has the 25hp Kohler and it's always struck me funny when I shut down because the engine will continue to run as normal for about 15-20 seconds after I turn the key off!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

Jeff

bkaimwood, please don't insinuate that others are giving bum advice unless you have this engine in this configuration and know what the "true" fix is.  It could be, the fix is exactly what they say know matter what you personally think.
Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

glassman_48

Scott,
I have a 38 hp kohler on a firewood processor that was built in 2012, I had the same problem.  I went from regular gas to premium, then went to the recreational gas without ethanol.  My local chainsaw shop also sold me a fuel additive that was for gas with ethanol in it.  I have heard good and bad things about the fuel additive too.  With the recreational gas if I use at least a couple of tanks full my dieseling/farting problem gets better.  Hope that helps.

timberjackrob

I have a 18hp kohler on lt 28 never experienced any diesling but have had occasional backfire.have you tried any additives in your gas I run some chevron injector cleaner thru mine on occasion.dont know if this helps it or not.i have also been using some lucas additive for protection from ethanol if the mill is not gonna be used for awhile.
208 timberjack, woodmizer lt28,case 455 trackloader with gearmatic winch,massey 4710, ford f250s ford f700

bkaimwood

10-4 Jeff...glad you put the "unless" in there...I apologize and don't mean to insinuate or offend anyone, truly looking to help. As I'm sure you noticed, I'm a fixer...when something doesn't function to expectation or as I would beleive its designed to function, I find out why. I was a diagnostician for 25 years, so its hard to let that go. I hate to see so many people have the same problem and have  to deal with it in ways I consider non conventional. You mentioned, in so many words, to soften my voice unless I knew what the true fix was, and had the mentioned Kohler engine, or something close to that...I do have a Kohler, and have had several over the years, and as mentioned, when I had listed issues it was always idle to high or lean fuel mixture...neither here nor there. I am only looking to help and guide as so many others here have done for me. For that, I am grateful. If anyone close to me has a mill with this problem, feel free to post or pm me...I would love to get my hands on one of these things...I would perform a diagnostic session in order to find the root cause, and repair it, in effort to help the dozens of owners on here with this issue...I'm sure the number is much higher...it goes without saying that this would be free of charge...thanks for listening, and again, by no means was I looking to offend anyone, just looking to motivate someone to entertain the idea that this is not normal.
bk

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