1998 Lazer Z wiith 25HP Kohler engine. deck wont engage

Markie

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
Hi Guys,
I have a 98 Lazer Z that wont engage blades after use. I can mow for an hour or so and deck clutch solenoid works fine. I can start and stop the deck with no problem. However, after a good warmup the deck becomes intermittent. When I pull the switch I can hear a slight noise like its trying but will not engage. If I turn the mower off and let it cool down everything starts working again. I replaced the push/pull switch thinking bad connection but did not fix it. Acts like the coil in the solenoid is weak. Is that possible? Has anyone had a similar experience?
 

geelee

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
your clutch has too much clearance due to wear at brake area, when a clutch it hot its not as strong a magnetic field as when cold. the only real fix is a new pto clutch. there are some aftermarket clutches that are a lot cheaper than the oem
 

Rivets

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
Before you purchase a new clutch try this test. The next time it happens, shut the engine off, turn the key switch to the run position and engage the PTO switch. If you here a loud clip it means the PTO is getting voltage and the clutch is engaging. If you don’t hear a clip, turn everything off and unplug the clutch wire down by the clutch. Now repeat the steps, key switch to run, PTO switch on and then check for voltage across the wires going to the clutch. If the PTO switch is working properly, you should get 12+ VDC. Let us know what you find.
 

Markie

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
your clutch has too much clearance due to wear at brake area, when a clutch it hot its not as strong a magnetic field as when cold. the only real fix is a new pto clutch. there are some aftermarket clutches that are a lot cheaper than the oem
Thanks for reply, that certainly what it seems like but never really heard temp affects magnetism of coil. Is there a source you recommend for the clutch? I will have to get the OEM p/n but always looking for new sources for parts.
Thanks again.
 

Markie

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
I will try the procedure you recommended. I'm pretty sure I have remember the click you referred to without the engine running. As I mentioned I do hear a kind of groan when I try to engage. I have to find a way to test the voltage while still connected to the clutch solenoid though. I'm afraid if I check with it unhooked I may get 12v but loaded with the solenoid may draw the voltage down. I will post my findings and thanks again for the input.
 

Rivets

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
You should get 12V and there is no solenoid in the PTO system or anything else to draw down the voltage. I’ve been doing this a long time and have never heard of heat affecting magnetism. Heat may change the resistance in the PTO coil winding, but that can be checked using an Ohm meter.
 

geelee

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
to rivits I have been a professional tech for 45 years. worked on exmarks since they started. the wont engage when hot problem on warner clutches ive seen countless times. caused by wear at the stop plate. and magnetism is affected by temp. look it up. also I would replace it with an extreme clutch
 
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Rivets

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
Geelee, yes magnets (metallic or ceramic) are affected by temperature, but with a clutch or coil the magnetic force is generated by electrical or electron flow, not the magnetic material which can be demagnetized by heat. In a clutch, coil or solenoid the magnet flux which is used to generate a magnetic pull or in the case of a coil is not affected by temperature. Temperature can break down the coils in these products a high resistance of some kind can cause the windings to overheat causing either a short or open, reducing or eliminating the coils ability to produce the desire magnetic flux or force. This is the reason I asked Markie to take a resistance reading of his clutch. He stated that he could hear the clutch kick in, but if his voltage is too low or internal resistance is too high, the clutch will not work properly. FYI, I have been working on small engines for more than a couple of years, and sometimes I even know what I am talking about. This is not the first time I’ve seen this problem and I always recommend troubleshooting before replacing parts. Just the educator in me I guess.
 

Markie

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
Well guys I finally got a chance to do a little troubleshooting. The clutch acted up again so I got my multi-meter. First I turned the engine off and pulled the blade engage switch out. I did hear a click but it sounded weak compared to other times i pulled the switch. With the clutch harness unplugged I measured the voltage and it was over twelve volts however, with the clutch harness plugged in the voltage dropped to 11.3 volts. It doesn't seem like a lot but could the lower voltage cause the clutch not to engage? unfortunately I didn't measure the resistance of the coil. I will have to measure it cold and again when it acts up to compare.
 

Rivets

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  • / 1998 Lazer Z wiith 25HP Kohler engine. deck wont engage
Yes a low voltage can cause the clutch to not engage properly. The next time it happens, you could hooking a charger or second battery in parallel and see if the added power changes anything. Still would like resistance readings.
 
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