Kohler 25 Command Pro CV730S problems

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  #1  
Old 05-27-08, 07:45 PM
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Kohler 25 Command Pro CV730S problems

I kinda hijacked another thread so I'll start a new one. I have a Craftsman GT5000 with a Kohler 25hp Command Pro (CV730S) . I bought it new 20 Feb 2005, the engine was made fall of 2004. It had a head gasket replaced Jan of 2006 and now another head gasket failed due to back fireing after shut down. I purchased a head gasket kit and replaced the #2 head gasket. It would only run on one cylinder so I suspected #1 had a bad head gasket as well. So, I replaced #1 cylinder's head gasket. When I can start it, it only runs on the #1 cylinder. I know this because When I remove the #2 plug wire it continues to run the same. When I remove the #1 plug wire it dies. I began suspecting a bad lifter on the #2 side but I don't think that is my problem anymore. After following the blead down procedure again, I let the mower sit for a day. It will start but still will only run on one cylinder (#1). I opened the valve cover on #2 and watched carefully to both sides of the rocker arm as I loosened the hex flange bolt (that holds the rocker down) and the valve spring remained still as the push rod backed out. This indicates that the lifters are indeed bleading down correctly and the valves should be seating properly. If the valve spring back out then I would suspect a bad lifter keeping the valve from seating.
So, I am still only running on one cylinder. Both head gaskets were replaced, both cylinder heads were reassembled the same way, to specifications. I get spark on both cylinders, and the fuel pump pulses fuel when the engine is turned over/started. When I can get the engine to start on the one cylinder I can see a small back fire (a puff of compressed air and fuel) out the carb. As if the valves are not operating correctly on the dead side (#2).
So what does anyone think I should do next. Any imput is appeciated.

Mike

 
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  #2  
Old 05-27-08, 11:11 PM
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Have you checked compression on the dead cylinder?
 
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Old 05-28-08, 10:59 AM
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There is compression, but I haven't measured the exact amount, yet. The compression eventually blows back out the intake manifold and out the carb. That is why I was suspecting the exaust valve not funcioning properly, and possible a bad liftter. But the lifters appear to be bleeding down and functioning correctly, and I can visually watch the valves move as I turn the engine over. I am starting to think I have an ignition timing problem. I believe this motor has the Smart-Start system. Are you familiar with this ignition system? As I mention before, I can pull the plug from #2 and ground it to the block and watch it spark as I turn the engine over. I just don't know for sure if it's sparking at the correct timing.
Thanks again for your help Cheese.

Mike
 
  #4  
Old 05-28-08, 10:34 PM
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I don't think timing is an issue. You're going to need to do a leakdown test to figure out what's going on...or pull the head again. Is there enough compression to force your finger off the plug hole while cranking the engine?
 
  #5  
Old 05-29-08, 07:57 AM
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Cheese,
I believe there is enough compression to do that. I'll give it a try today. Are you suspecing the the new head gasket failed already?

Mike
 
  #6  
Old 05-29-08, 10:08 PM
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No...just trying to find the problem area. I would suspect the problem to be related to the head and related items only because that's what has recently changed. You removed the head, and the problem occurred. I'm still thinking valve/lifter related problem, or at least I want to eliminate it before moving to something less obvious.
 
  #7  
Old 05-30-08, 09:38 AM
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Thank you cheese, I welcome any information at this point. Let me give you a little more info. The #2 cylinder did have a leak in the head gasket. I could visually see it leak and puff out the side of the cylinder. But, the mower would still run with just a little loss of power. I knew a head gasket repair was in my future (very common with this engine and I had one replace under warantee already).
One day I started it up drove across my law, returned the throttle to idle, the stepped off the mower when it died. I jumped back on and it wouldn't fire up. I thought the head gasket finally went. I ordered a replacement kit, installed it, and it would only run on one cylinder the #2 (the one with the new gasket). I know this because I would remove the #1 cylinder spark plug wire and it would continue to run poorly. I assumed that #1 head gasket was blown as well so I ordered a kit for that one and installed it.
Now it will only run on cylinder #1, the one with the second gasket replaced. This is why I'm suspecting a timing or ignition problem. Each cylinder has a new head gasket and the engine has run on one or the other cylinder but not both (if it did we wouldn't be having this disscusion).
I'm about to give up and drop it off at a service center to be repaired. Does this new info give you any ideas?

Mike
 
  #8  
Old 05-30-08, 10:33 PM
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Get a brand new pair of champion RC12YC plugs and put them in before going any further, or at least swpa plugs from one cylinder to the other to be sure there isn't something odd happening with the plugs. If it still skips, see if the skip moved to the other cylinder.
 
  #9  
Old 05-31-08, 10:40 AM
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Good advice Cheese. I have had the plugs out a million times, cleaning them and to check for spark. It would be funny if one was faulty and I put it the other side causing it to run on the other cylinder. I'll let you know what happens after I through two new ones in.

Mike
 
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Old 05-31-08, 11:31 AM
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Post your model/spec numbers, so we can see if your engine
has "Smartspark" or S.A.M. module, they can cause all sorts of troubles. Being on a Craftsman, it likely does.


Fish
 
  #11  
Old 05-31-08, 12:43 PM
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Installed two new spark plugs, no change.
Fisher here are the numbers;

Craftsman GT5000 with 25 hp Kohler command Pro
Family 4KHS.7252GC
MODEL CV730S
SPEC NO CV730S-0029
BUILD DATE 05/21/2004

Let me know what you think.

Mike
 
  #12  
Old 06-01-08, 08:37 AM
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Mike,
I fixed my #2 cylinder not firing problem on my Kohler CV23S. Believe it or not it was the carberator. I have a feature on my carb called an Accelerator Pump. I was able to disable it by clamping off the small hose between the pump and the intake. As soon as I clamped this hose my engine changed tone and ran smooth and sounded great. I am now able to pull either plug wire and keep the engine running. My best guess is the fuel mixture was to rich for #2 to fire consistently. I am not sure why #1 would fire though. Maybe a slight difference in the valves or compression between the two cylinders causing more or less fuel to #1. Just a guess. Now I have to fix this accelerator pump or leave it disabled. This paticular carburetor has only a Low Speed adjustment, no High Speed. I hope you get yours going although you probably have a different problem. Sometimes I hate these small engines. good luck.

John
 
  #13  
Old 06-01-08, 09:07 AM
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Thanks for the info John. I look at my carb today.

Mike
 
  #14  
Old 06-01-08, 09:07 PM
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That's a new one for me too...I haven't run into that situation yet. I'll keep that in mind. I guess the accelerator pump is leaking most likely, causing a rich mixture like you said. Is the accelerator pump closer to the #2 cylinder side of the intake than #1?
 
  #15  
Old 06-02-08, 05:15 AM
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The optional accelerator pump feature is mounted on the side of the float bowl, no bigger round than a 50 cent piece and a half inch thick. It looks like it receives its gas from the bowl and pumps it into a small hose to a nozzel just under the air intake and choke valve. It is really inclusive to the carb and not closer to either cylinder. I still do not have the answer why it caused cylinder #2 not to fire. but after mowing an acre yard yesterday I noticed the mower using less gas and except on start-up the exhaust was clear for the first time in a few months.
 
  #16  
Old 06-02-08, 10:57 AM
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I didn't get a chance to look at my carb, yet. I did pull the #2 spark plug, place my finger on the hole and turned the engine over. Plenty of compression to blow my finger off the hole (not an exact measuement of compression but good enough for now). My fingure was dry, so I placed a paper towel over the hole and turned the enging over for 30 sec. Still dry. I'l starting to believe that I have spark, compression, fuel to the carb, but no fuel making it to the #2 cylinder. I'll check the little hoses on the carb and accelorator pump is equiped.

Mike
 
  #17  
Old 06-06-08, 02:37 PM
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I am about to take apart my carb and trouble shoot. Hopefully, lack of fuel to #2 is my problem.

Stay tuned!

Mike
 
  #18  
Old 02-18-09, 02:10 PM
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Kohler command Pro CV730S

I gave up on my Kohler last summer and bought a push mower. It's almost spring time and I'm ready to reattack my problem. My father inlaw sugested adjusting the timing. Does anyone know how to adjust the timing on a Kohler command Pro CV730S, or how to check it?

Thanks,
Mike
 
  #19  
Old 02-18-09, 07:08 PM
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There is no timing to adjust or set. It is fixed timing. If it's running on one cylinder, but not the other, timing isn't the problem. I suggest putting an inline spark tester on the dead cylinder and see if it is firing even though you've seen spark at the plug during cranking.
 
  #20  
Old 02-19-09, 06:24 AM
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It could also be a valve problem causing the dead cylinder. You can download a Kohler service manual for your engine at the Kohler website.

www.kohlerplus.com

enter as a guest, you can also find Illustrated parts lists there.

Best of Luck....
 
  #21  
Old 02-19-09, 03:08 PM
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Thanks for the response guys. It is no longer running on one cylinder. As I turn it over, compression builds up and almost stops it from turning over (too much pressure when the spark SHOULD fire). Can anyone tell me if I have "Smartspark" or S.A.M. module or the another type of ignition? Maybe that's my problem.


Craftsman GT5000 with 25 hp Kohler command Pro
Family 4KHS.7252GC
MODEL CV730S
SPEC NO CV730S-0029
BUILD DATE 05/21/2004


Thanks,
Mike
 
  #22  
Old 02-19-09, 05:53 PM
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Sounds like a low battery or oil and or gas in the cylinders. You can get it running, but it runs on both cylinders now?
 
  #23  
Old 02-19-09, 10:15 PM
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No, it does not run at all. I can only turn it over and I can feel the compression slowly building up. Feels like it's not getting the spark at the right time. When the compression builds up the RPMs slow down until the valves open and let the pressure out with a puff of unburnt fuel and air. I think my problem is with the ignition system=SMARTSPARK I think. I don't want to keep throwing parts at it but would replacing that module help?
 
  #24  
Old 02-20-09, 04:29 PM
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Originally Posted by franknbeans View Post
No, it does not run at all. I can only turn it over and I can feel the compression slowly building up. Feels like it's not getting the spark at the right time. When the compression builds up the RPMs slow down until the valves open and let the pressure out with a puff of unburnt fuel and air. I think my problem is with the ignition system=SMARTSPARK I think. I don't want to keep throwing parts at it but would replacing that module help?
Replacing the S.A.M. will help, but only if it's bad!

Download the service manual and follow the troubleshooting guide for the ignition on your engine. This way you can determine if it's one of the modules, S.A.M. or an outside problem with your ignition.

Ignition components for this engine can be quite expensive, you will only want to replace something, if it's bad and needs replacing.
 
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Old 02-20-09, 08:42 PM
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There's no way any of us can tell you what is wrong without you doing something to aid us in the diagnostic process. Replacing the SAM probably won't do anything other than thin your wallet by $100 or so...but I don't know that for sure without more info.

I know when I work on a mower that won't crank fast enough to overcome the compression stroke, I start looking at battery, starter, and other things instead of expensive ignition modules.
 
  #26  
Old 02-21-09, 05:09 AM
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Originally Posted by cheese View Post
I know when I work on a mower that won't crank fast enough to overcome the compression stroke, I start looking at battery, starter, and other things instead of expensive ignition modules.
Doesnt this also sound like it could be a valve adjustment problem ??
 
  #27  
Old 02-21-09, 02:12 PM
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On most solid lifter engines, yes, but not on a kohler command with hydraulic lifters that don't have any adjustments.
 
  #28  
Old 03-25-09, 10:24 AM
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Update on my Kohler problems

After 10 months of problems I finally dropped it off at a local small engine repair shop. It was the timing. All of the backfires that caused the head gaskets to blow, slipped the flywheel off 90 degrees, which made the timing off. I will install a fuel cut off valve and shut off fuel to the carb prior to shutting down when hot. This should prevent anymore backfires, save my head gaskets and timing.

Thanks for all of the help.Beer 4U2
Mike
 

Last edited by franknbeans; 03-25-09 at 01:19 PM.
  #29  
Old 03-25-09, 10:00 PM
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Wow, yeah, 90 degrees off would definitely not let it crank up. Is that also the cure for the running on one cylinder issue? (maybe "seemingly" running on one cylinder?)

Glad you got it fixed and thanks for posting the update!
 
  #30  
Old 03-28-09, 11:06 AM
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Cheese,
I believe all of the backfires caused the shearing of the flywheel key. I changed the head gaskets on both cylinders but could only get the engine to run (very rough) on one cylinder. My guess is that the flywheel slipped passed the sheared key just enough to allow some timing to the only running cylinder. Eventually, the flywheel slipped to 90 degrees, and the engine died. It obviously wouldn't run again at that position.
I will let the engine idle for a few minute before shutting down. This will save the head gaskets and any more future damage to the flywheel key. I was told that there is carbon in the cylinders that are glowing red hot that are causing the backfires. So, letting the engine cool for a few minutes, cools the carbon, and prevents the backfires.

Thanks again for your help Cheese, and to all others!Beer 4U2
 
  #31  
Old 08-23-09, 09:32 PM
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Thumbs up CV 730 / CV735 / CV740 Engine wil not run

I've read over all of your posts you have received regarding your problem. Not sure if this will help you out being it's so late, but I have a Kohler Command CV 735 in a Craftsman DG 5000 with 54" deck. It only had 52 hours on it when I developed a run issue. The motor would start but it would run very lousy. While running the engine and throttling it up, the engine would backfire a little bit and take longer than normal to spool up to high RPM. When I would attempt to drive the lawn tractor forward or reverse it would exhibit very little power. I had checked SPARK at both cylinders,OK, checked FUEL DELIVERY,OK, checked COMPRESSION (170psi),OK and even checked the SMART SPARK MODULE for ignition advance and it was working properly. I eventually spoke to a Kohler distributor about this issue because it had only been out of warranty for one month and the problem had me baffled. What I found out was when the engines are shut down they have a tendency to momentarily turn backwards right before coming to a complete stop. The fuel shut off at the carburetor is supposed to slam shut; therefore, cutting off fuel supply to the engine. Well, this causes a problem over a period of time when shutting down these engines. The flywheel is jolted hard enough on the crankshaft and it eventually sheared the flywheel key on the crank just enough that timing was thrown off a few degrees but would continue to run very poorly. This Woodruff Key costs a couple of dollars. Hope this helps you out. :USAF:ercman69
 
  #32  
Old 07-10-10, 11:34 PM
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Kinda late I know

My Kohler did this too. Backfire, run backwards when I shut it off so here 's the fix. Back the idle screw out OR remove it then idle it using the throttle cable. It takes three things to run, air/fuel/spark. Backing the screw out allows the throttle butterfly to fully close which eliminates the air. No air = no combustion = problem solved. Worked for me.
 
  #33  
Old 04-27-12, 10:52 PM
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Kohler CV730S engine choke return spring installation

I also have a Craftsman GT5000 with Kohler CV730S engine (SPEC NO CV730-0029, BUILD DATE 05/27/2004). I had the float needle stuck in the Nikki one-barrel carburator, took it off, cleaned it up. Now I'm having trouble geting the throttle and choke linkage put back together correctly. Found the Kohler service manual and nice YouTube video on adjusting the governor linkage that shows the links properly assembled. Only thing left is the choke return spring that goes on the back side of the control bracket.

Can anyone help with a picture or diagram showing how the torsional choke return spring installs?
 
  #34  
Old 07-01-14, 08:55 AM
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Mystery Part

I too have one of these CV730-0017 engines, purchased in 03. I am now having the head gasket problem. I have ordered parts and started the tear down. When I removed the air cleaner cover I heard a metallic object drop ( thinking it was a washer) when I located it I found it was a ball bearing the size of a pea. I cannot find where it came from, is it possible it is from the breather separator, maybe a check valve ball. Anyone have any ideas.
 
  #35  
Old 07-01-14, 10:04 AM
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It goes in a tube in the little cup that bolts on over the throat of the carburetor.
 
  #36  
Old 07-03-14, 05:12 PM
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Thank you Cheese I thought so, I asked a Lawnmower shop mech and he had no idea. One question, I tried putting it in from the outside and it did not fit so I will assume it goes in from the inside. One other question I am doing the head gasket change do you know if any of them require gasket cement, and should I replace the valve seals also?
 
  #37  
Old 07-03-14, 08:48 PM
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Don't use any kind of cement, just a new gasket on a clean mounting surface. Torque the bolts properly and check to be sure you have the proper head bolts. These engines had an update for the head bolts. The new ones are about the same thickness all the way down the bolt shaft. The old style ones taper down and get big again at the threaded area. If yours have the taper, replace them with new ones.
 
  #38  
Old 07-04-14, 02:41 PM
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I haven't pulled off the heads yet due to the extreme heat and humidity and now passing hurricane, so I have no idea what the bolts look like. I have received the new upgraded gasket kits and they only have brass colored nuts in the package. On previous post I read that the upgraded kits have the new bolts but not the ones I received. I will let you know what I find.
 
  #39  
Old 07-08-14, 04:34 PM
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What a mistake

I tore down the engine and found that the head gaskets were fine, on apparent leaks. Valve seal good, breather reed looks fine, I can only think that the breather separator is clogged and cause the blowback forcing oil back to the intake. Now I have the task of reassembly ( those bottom bolts that hold the engine controls and air intake bracket are a *****) cant get my hands under to put them back, I might have to remove the engine all together off the frame.
Any ideas, I am really exhausted.
 
  #40  
Old 07-08-14, 06:43 PM
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Rings or crankcase ventilation would be the only other things I would be thinking of unless there was gas in the oil.
 
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