I have five Walker's with Kohler engines. WHen I went by the dealer on Thursday he said Kohler had upgraded the breather tube (tube between crankcase and carburetor) because there had been some problems with cracking. My mechanic said he had rebuilt several engines because of cracked breather tubes. He suggested I change all of mine. I checked two this morning and both had cracks, so I replaced them. I will replace the others in the next few days. I had had a couple of engines fail because of breather tube problems, so I am taking no chances. I just thought others might be interested in the information. The may be old news. if it is old news, I apologize.
Kohler breather tube ALERT!
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mcambrose
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I have five Walker's with Kohler engines. WHen I went by the dealer on Thursday he said Kohler had upgraded the breather tube (tube between crankcase and carburetor) because there had been some problems with cracking. My mechanic said he had rebuilt several engines because of cracked breather tubes. He suggested I change all of mine. I checked two this morning and both had cracks, so I replaced them. I will replace the others in the next few days. I had had a couple of engines fail because of breather tube problems, so I am taking no chances. I just thought others might be interested in the information. The may be old news. if it is old news, I apologize.
Joined
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437 Posts
25hp Kohler, if so I feel for ya. Only one of many plagues in that motor! Dumped mine and got a new KAI 28hp
Improved Breather Hoses
Recent reports of cracked or deteriorating breather hoses on
Command, Aegis, and Courage engines have prompted a
material change. A previous material change in 2004 has been
found to be inadequate in some applications for long term
reliability.
New hoses with improved ozone protection have been
developed and carry new part numbers. They also have the
part number printed in white for easy identification. Please
refer to the chart found on Service Bulletin 279 in Section 10
for the cross reference to the new breather hose part numbers.
All engines should be routinely inspected for deteriorating or
cracking breather hoses. Replace any deteriorated or cracking
hoses with a new breather hose. Only file a warranty claim if
the engine is within the warranty period.
Please see the attached file for the chart.
Recent reports of cracked or deteriorating breather hoses on
Command, Aegis, and Courage engines have prompted a
material change. A previous material change in 2004 has been
found to be inadequate in some applications for long term
reliability.
New hoses with improved ozone protection have been
developed and carry new part numbers. They also have the
part number printed in white for easy identification. Please
refer to the chart found on Service Bulletin 279 in Section 10
for the cross reference to the new breather hose part numbers.
All engines should be routinely inspected for deteriorating or
cracking breather hoses. Replace any deteriorated or cracking
hoses with a new breather hose. Only file a warranty claim if
the engine is within the warranty period.
Please see the attached file for the chart.
I checked four of my five machines including a 20hp, 2003 model with 250 hrs. All units had cracks in the breather tubes. In fact, I just had an engine rebuilt that I received back yesterday. I was installing the engine and decided I should check the breather tube. It was terribly cracked and it was nota tight fit on the bottom. I could have ruined the enine rebuild in a short while. Thanks to my mechanic for giving me the information.
Joined
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796 Posts
Can someone take a Pic of this hose (cracked one) on the engine (25hp) so I can get a clear view of were its at? Is there two or just one. THANKS
You have other problems if that is the case. The breather lets air out, not sucks it in. Thats what the valve is for
Thanks a lot that will definitely improve things hate to see machine come in for weekly maintenance and those are off.
Joined
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171 Posts
You are uneducated on how the breather system works.
In the crankcase, below the heads, there is vacuum. On the number 2 cylinder head, there is pressure to help return oil from the head to the crankcase. In the number 1 cylinder head, crankcase pressure leaves through the breather filter and goes to the intake.
Old automotive applications let crankcase pressure (caused from blowby) to escape directly to the atmosphere, but this creates emissions and environmental issues.
Late to the party on this one...but I've noticed oil coming from that little screw-a-magid on the breather cover, I can safely assume the gasket is blown? Otherwise, not issues with the hose. Would the blown gasket have the same effect as a cracked hose? If so, from previous posts, how could this ruin the engine? The small "filter" under the breather cover was barely noticeable. Could this cause the engine to lose power after 30-40 minutes? My full list of symptoms below:
2009 Scag Turf Tiger
27hp Kohler Command Pro PA-CH740-0021
650 hours (653 hours now, bought used 22June2018)
Starts strong, runs great for about 30-40 minutes then begins to lose power while blades are engaged. I can release the blades and let the sucker stand for a few seconds and the engine begins to sound "right" again. Then…once I start mowing again…same thing, engine loses steam. I can let is sit for 30-40 minutes and go through the whole routine of mowing for 30-40 minutes with no problem before the issues start again. There also seems to be an oil leak near the dipstick.
Here's what I have done:
-Compression check: 120psi on both cylinders. I've heard this number doesn't mean much for these engines because they have a built-in release valve.
-Replaced spark plugs.
-Drained all the previous owners gas and replaced with "clean" gas.
-Checked for spark with inline tester both resting, under load, and when it is acting up. Clean spark. At least that what the tester tells me.
-Cleaned carb.
Could it be:
Ignition coil? I know there will be a consensus that the DSAI thing is junk and my problem. My ignition coil number is 24-584-36. The kit that is supposed to "fix" this direct ignition problem does not show compatibility with my model coil number.
Worn/sticking valves? If so, can this be rebuilt with long term success or will the problem eventually resurface?
Carburetor?
Tiny rip in the seat?
2009 Scag Turf Tiger
27hp Kohler Command Pro PA-CH740-0021
650 hours (653 hours now, bought used 22June2018)
Starts strong, runs great for about 30-40 minutes then begins to lose power while blades are engaged. I can release the blades and let the sucker stand for a few seconds and the engine begins to sound "right" again. Then…once I start mowing again…same thing, engine loses steam. I can let is sit for 30-40 minutes and go through the whole routine of mowing for 30-40 minutes with no problem before the issues start again. There also seems to be an oil leak near the dipstick.
Here's what I have done:
-Compression check: 120psi on both cylinders. I've heard this number doesn't mean much for these engines because they have a built-in release valve.
-Replaced spark plugs.
-Drained all the previous owners gas and replaced with "clean" gas.
-Checked for spark with inline tester both resting, under load, and when it is acting up. Clean spark. At least that what the tester tells me.
-Cleaned carb.
Could it be:
Ignition coil? I know there will be a consensus that the DSAI thing is junk and my problem. My ignition coil number is 24-584-36. The kit that is supposed to "fix" this direct ignition problem does not show compatibility with my model coil number.
Worn/sticking valves? If so, can this be rebuilt with long term success or will the problem eventually resurface?
Carburetor?
Tiny rip in the seat?
Joined
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14 Posts
Your Kohler Command engine does not have compression release. The compression, as listed on page 20 of the service manual below, should be at least 160psi. At 120psi, you are on the low end of what is barely acceptable. You should perform a leakdown test as was suggested. The coil number you have is for the conventional ignition system so either a previous owner made the changeover or your specific engine was not affected by the bulletin.
http://www.kohlerengines.com/engines/onlinecatalog/pdf/sm_24_690_06.pdf
http://www.smallenginesuppliers.com...uppliers.com/html/engine-specs/kohler/SB-300_Improved+DSAI+Ignition+Modules.pdf
http://www.kohlerengines.com/engines/onlinecatalog/pdf/sm_24_690_06.pdf
http://www.smallenginesuppliers.com...uppliers.com/html/engine-specs/kohler/SB-300_Improved+DSAI+Ignition+Modules.pdf
Thanks. Just to confirm, part # 25 707 03-S will not work for me? The suggestions are about 50/50...50-I can't convert, 50-use [URL='http://i.viglink.com/?key=63fa33e5a190758d306ce6fba77c5655&insertId=ee6cb6c40aec52d3017b616afff5f441&type=H&mid=undefined&exp=60%3ACI1C55A%3A21&libId=jje8tkh90100qthb000DAoczexbz2&loc=https%3A%2F%2Fwww.lawnmowerforum.com%2Fshowthread.php%2F49261-Scag-Turf-Tiger-Kohler-Command-Pro-27-Frustrations&v=1&out=https%3A%2F%2Frover.ebay.com%2Frover%2F1%2F711-53200-19255-0%2F1%3Ftoolid%3D10029%26campid%3DCAMPAIGNID%26customid%3DCUSTOMID%26catId%3D11700%26type%3D2%26ext%3D232805708620%26item%3D232805708620&ref=https%3A%2F%2Fwww.lawnmowerforum.com%2Fshowthread.php%2F49261-Scag-Turf-Tiger-Kohler-Command-Pro-27-Frustrations%2Fpage2&title=Scag%20Turf%20Tiger%2FKohler%20Command%20Pro%2027%20Frustrations&txt=%3Cspan%3E25%20%3C%2Fspan%3E%3Cspan%3E707%20%3C%2Fspan%3E%3Cspan%3E03%3C%2Fspan%3E%3Cspan%3E-%3C%2Fspan%3E%3Cspan%3ES%3C%2Fspan%3E']25 707 03-S.
Would 25 707 03-S upgrade the coils and eliminate the module system?
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14 Posts
Some systems required flywheel replacement in addition to the coils. If your system is not covered by the bulletin, the best bet would be to call your Kohler dealer or Kohler themselves and ask them what conversion would work for your serial number. Before you do anything, I would do the Leakdown test and crankcase vacuum test as was suggested. You may be looking at repair costs that might get you thinking of a replacement engine.
Thanks for the feedback. Worst case scenario (post leakdown and vacuum test)...what types of issues could I expect that would not be fixed by a rebuild kit?
Joined
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14 Posts
Worn cylinders. And you have not disassembled the engine yet. You could have crank/rod bearing wear, cam/lifter wear.
Most times it is easier to get a replacement engine with a 3 year warranty, in my opinion.
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