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pcpro15
06-28-2006, 10:50 PM
I got an exmark lazer Z (kohler engine 25hp air cool) and all of a sudden it wants to play games. Sometimes when at full throttle with blades on, the engine pitch will switch back and fourth between normal and muffled. When the engine sounds muffled, it loses major power and RPM's and makes it almost impossible to cut grass with. Then there are those other times when it wants to run perfect for about a stripe of grass or two and then its back to spitting and sputtering. Air filters clean, Cleaned spark plugs, oils good, new gas. I mean I went over just about everything I could think of with out buying new parts. When the tractor ran good before this started happening, the muffler used to get very hot very quickly. After 2 minutes, the muffler is unbearable to touch as you might expect but also becomes close to a cherry red around 5 or so. This leaves me to believe it is running lean??, but the oil also becomes unbearably hot also. It doesn't seem like the oil is staying cool and if you open the yellow cap that you pour oil in, you see steam come out. I think the tractor is probably on it's way out, but I can not even come close to afford a new tractor at this point. Any suggestions would be appreciated.

Thanks in advance,
pcpro15

TLS
06-28-2006, 11:08 PM
Fuel filter?

Gas tank vents?

How many hours?

FIXDISS
06-28-2006, 11:19 PM
I got an exmark lazer Z (kohler engine 25hp air cool) and all of a sudden it wants to play games. Sometimes when at full throttle with blades on, the engine pitch will switch back and fourth between normal and muffled. When the engine sounds muffled, it loses major power and RPM's and makes it almost impossible to cut grass with. Then there are those other times when it wants to run perfect for about a stripe of grass or two and then its back to spitting and sputtering. Air filters clean, Cleaned spark plugs, oils good, new gas. I mean I went over just about everything I could think of with out buying new parts. When the tractor ran good before this started happening, the muffler used to get very hot very quickly. After 2 minutes, the muffler is unbearable to touch as you might expect but also becomes close to a cherry red around 5 or so. This leaves me to believe it is running lean??, but the oil also becomes unbearably hot also. It doesn't seem like the oil is staying cool and if you open the yellow cap that you pour oil in, you see steam come out. I think the tractor is probably on it's way out, but I can not even come close to afford a new tractor at this point. Any suggestions would be appreciated.

Thanks in advance,
pcpro15

When you cleanned plugs did you notice any black carbon deposits or oil on plugs ? From what I have read on other posts there may be a head gasket issue . Also have you drainned float bowl to see if there may be some water or sediment in it ? Need to also check blower housing and cooling fins for debris or blockage.And last check the muffler and exhaust for damage or blockage.Post model #'s and I'm sure someone here can give you some other advice.

TLS
06-28-2006, 11:21 PM
Yeah....I've heard mufflers go, but usually they just get loud.....but if a baffle broke loose, it could cause a big restriction that could come and go.

pcpro15
06-28-2006, 11:30 PM
The spark plugs had some carbon residue on them even after I cleaned them with WD-40. The engine has around 1600 hrs. Fins are clean. Gas cap vents are good because it is happening on both tanks. I took the muffler off because the baffles had been replaced before. The muffler is still off and problems continue. I am not sure of the serial number at this point because the mower is outside. The model number is LZ25KC604. I purchase this mower 2nd hand with 1300 hrs. on it and have had it for about 5 years now. I am going to look into a new fuel filter tomarrow morning.

Thanks everyone for the imput,
pcpro15

Restrorob
06-28-2006, 11:42 PM
I am not sure of the serial number at this point because the mower is outside. The model number is LZ25KC604.


Read the 5th thread from the top in this forum, Then post the engine numbers.......

pcpro15
06-28-2006, 11:48 PM
I appreciate your willingness to help Restrorob, but I do not have access to the mower at this moment, so I gave the next best thing. The model number. The engine was made probably around 2001 although I am not positive. I know where that number is at, and when I go out in the morning, I will be sure to get the number for you.

Thanks in advance,
pcpro15

FIXDISS
06-29-2006, 12:08 AM
Hey Rob, haven't talked to you in a while. Looks like site administrator is giving you a hard time by enterring posts and making the "Read before posting" msg drop down further all he time. Ha Ha. Have really picked up a lot from your replies to guests here. Thanks.

pcpro15
06-29-2006, 10:10 AM
The serial number for my tractor is in the 190,000 range.

Exmark Operator Manual (http://exmark.com/pdfs/850612.pdf)
Exmark Parts Manual (http://exmark.com/pdfs/850613.pdf)

Don't Know if those links are necessary, but I assume that is what you need the serial number for.

Thanks in advance,
pcpro15

pcpro15
06-29-2006, 11:09 AM
The Model number for the engine is CH25S
The Spec Number for the engine is 68606

Tech man
06-29-2006, 12:30 PM
We had a Scag, with the same engine, that was doing the same thing, a baffle was loose in the muffler and restricting a exaust port.

pcpro15
06-29-2006, 03:16 PM
Thats what it sounded like too, but I took it off and still have the same problem. I took a video of it, and took it to one of my friends and he suggested I get new spark plugs and that the coil needs to be replaced. He said it goes good until it gets warm, and then it drops out and picks back up and repeats. I took his advice and got the high dollar plugs for it and it did infact help. I was able to finish cutting grass as it seemed to help at high rpm. The problem still remains and is now showing during idle. At a 1 minute idle, its stalled. With the muffler off initially, both of the tubes seemed to have a pretty good amout of carbon buildup. With the new plugs this afternoon, It didn't "dip" and now the right tube is clean / whiteish while the other is slightly clean, but gets recoated with carbon when the thing fires. I can guess that the clean tube is causing problems because when you check the airflow out of the tubes, one is considerably stronger than the other. Thats how it seems to me. I got it quoted today to be fixed and its gonna cost me around $175, with the coil and 2hrs labor. Seems kind of steep, but nothing on this mower is cheap. They said coil, but are they refering to the ignition coil, or a different coil? The actual coil end seems almost brand new. The side that fires has a slightly rusted ignition coil end where it meets the sparkplug, but aparently is not causing any problems. I cleaned both ends with WD-40 and removed what seemed to be "rusty dirt" from inside both caps.

pcpro15
06-29-2006, 05:13 PM
No body had mentioned anything about a lifter. Could it possibly be that a lifter is going bad? Since I replaced the plugs, the mower now stalls out when idle for about a minute. If i leave it in idle, put on a little choke, i can start to see flame from within the motor. The left side lifter you can tell is obviously being pushed up by the pressure and when it is released, the flames surround the lifter. The other side which seems to be the bad side looks like the lifter is pumping, but sometimes has more orange flame has varied size, and is not surrounding the lifter all the time. It looks as if the flame is more in the tube, rather than comming form the lifter hole when the motor gets in its mood. I appreciate all the help I have gotten, but this seems to be more than I would be able to fix on my own. Again thanks everyone!

pcpro15

MowerMedic77
06-29-2006, 06:01 PM
[QUOTE=pcpro15] now the right tube is clean / whiteish while the other is slightly clean, but gets recoated with carbon when the thing fires. I can guess that the clean tube is causing problems because when you check the airflow out of the tubes, one is considerably stronger than the other. /QUOTE]
I would check for an intake gasket leak on the side with the whiteish tube may have an intake gasket leak causing you to run lean on that cylinder.

pcpro15
06-29-2006, 06:50 PM
Sorry, but I am not familiar with where the intake gasket is located. The air comes in throught the black cover which covers the air filter and then goes directly into the carb. The only thing that I could think of would be the dual oil covers. One was replaced about a year ago and resealed (the problem side). It is still intact and has no visible leaks. The other cover is slightly discolored as it has not been replaced, but both become extremely hot under normal conditions.

FIXDISS
06-29-2006, 07:18 PM
Sorry, but I am not familiar with where the intake gasket is located. The air comes in throught the black cover which covers the air filter and then goes directly into the carb. The only thing that I could think of would be the dual oil covers. One was replaced about a year ago and resealed (the problem side). It is still intact and has no visible leaks. The other cover is slightly discolored as it has not been replaced, but both become extremely hot under normal conditions.

The carb. mounts onto the intake. There is a gasket there. Check for loose bolts. Follow the intake to both sides of the engine. Should have a gasket on each cylinder. Again check for loose bolts.If bolts are loose on either of these points then snug them up and start engine. Spray a little of that wd-40 around the seating area of the gaskets and note whether engine speed changes. If so, then you have a gasket gone bad and will need to replace it. :dizzy:

pcpro15
06-29-2006, 09:52 PM
Went out, checked, everything looks good for the most part as far as gaskets and seals. I put new spark plugs in if i didnt mention it yet. It is a lot easier at night to tell which side is the bad side. With the muffler off, you can see a constant blue flame each time it fires. Since the one side fires consistantly, it is always blue. The other side has an intermitant blue flame each time it desides to fires. Since the one side still fires, I assume the fuel filter is clean as it has no problems considering it was in the shop like 2 months ago to have it looked over. I plan on replacing the fuel line from the splitter to the engine. Is it the coil, or is it a lifter?

thanks in advance,
pcpro15

tallimeca
06-30-2006, 12:43 PM
While the engine is running, let it get warm. Take a screw driver with an insulated handle, and pop one side spark plug wire off. And listen to the engine for a few seconds, then shut it down.

Then put it back and try the same thing with the other side.

Easiest way to pinpoint if you have an isolated problem on 1 cylinder, or an issue with the whole motor/machine.

These 68606 series engine have had their issues. We have seen a ton of them running them in the Bunton BZT1250's. Most are pretty reliable but mainly normal maintanence/breakage like head gaskets and coils.

You usually see less isssues on a Z because it doesn't run as hot. There are updated head gasket kits from Kohler on these units. Comes with gasket, valve cover gasket and new head bolts.

Sounds to me more like a coil, or SAM module, which a kohler dealer should have the equipment to test. This module runs the coils.

1600 hrs on this motor could pretty much put it at the end of it's rope. They are only rated by Kohler for like 1500 hours. If the previous owner was not good at maintaining it, the cylinder bores could now be out of round and causing blow by and lower compression when it heats up.

Good luck.

pcpro15
06-30-2006, 01:04 PM
I did infact do what you said to last night. The problem is on one cylinder. When you pull the fully working side, the other side struggles to stay alive and eventually dies. If you pull the non working, the working side keeps going. The sam module is like 100 dollars, and the Coils are 50 dollars with like 65 dollars * 2hrs shop labor fee. In worst case, lets assume everything listed is bad. Thats almost 300 dollars for a motor rated for lower hours. We have gotten our use out of it as we are residental, but it seems as if this engine is going to nickle and dime me for the rest of its life. I guess its time to suck it up and just drop a new motor in it. For this repair, i am dropping 1/5 of the cost of a new motor in it. The frame is solid and has more metal than the newer ones. Thanks everyone for the help, I now know I definately have to take it to a shop now and can not be fixed easily or get a new motor.

Thanks everyone,
pcpro15