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Discussion Starter · #1 · (Edited)
Trying to fix a hard starting Scott’s 1642H. I’m nearly certain the issue relates to the valves; the mower won’t crank unless I manually rotate the engine past the compression stroke. I’m having trouble finding what the correct setting is for the intake and exhaust respectively. Can anyone point me to a good resource?

thanks!

UPDATE
Just pulled the valve cover and rolled the cylinder to TDC. From what I can tell there is no gap. I can’t get a feeler gauge between the top of the valve and the rocker arm on either intake or exhaust. First time doing this so I’m not entirely sure what I’m looking at. See picture below. Any pointers would be appreciated!
 

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I assume that you figured out from tabora's post that the valves are not adjustable and do not have a gap. The slow starting might be fuel related. I had a Deere LT160 with Kohler CV16 that took forever to crank if it hadn't been run for a few weeks. Once it had been started it cranked fine the rest of the day or the next few days. I think it just took a while for the fuel pump to fill the bowl from the rear tank.
Also be sure that the choke plate is closing all the way.
Cannon
 

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Discussion Starter · #4 ·
I assume that you figured out from tabora's post that the valves are not adjustable and do not have a gap. The slow starting might be fuel related. I had a Deere LT160 with Kohler CV16 that took forever to crank if it hadn't been run for a few weeks. Once it had been started it cranked fine the rest of the day or the next few days. I think it just took a while for the fuel pump to fill the bowl from the rear tank.
Also be sure that the choke plate is closing all the way.
Cannon
Thanks Cannon! Yep - I figured it out when I saw the word “hydraulic”. Learning something new every day! :)

It’s kind of a bummer because the valve lash issue sounded like it could be the source of my problems. I haven’t noticed the starting getting any easier after I replaced the gas with fresh. In fact, the motor doesn’t want to turn, even after replacing the starter. So far the only thing that works is manually turning the engine to just past compression. That seems to give the starter enough of a run up to get past the next compression. I’m starting to wonder if something is bent somewhere…
 

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Do you know if it is equipped with an
(ACR) "Automatic compression release?"
It's a little weighted thing on the exhaust valve cam that holds the exhaust valve open just a bit until the motor starts. Then centrifugal force spins it so the exhaust valve closes all the way. If you google it, it will explain it better than I can. It's kind of a notorious Kohler problem on the single cylinder engines.
But it's under the top engine cover so ya gotta crack open the case to get to the cams. I'll try to attach a picture and help you any way I can if it has the ACR.
Food Ingredient Cuisine Wood Baked goods

Wood Door Auto part Hardwood Metal
 

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Thanks Cannon! Yep - I figured it out when I saw the word “hydraulic”. Learning something new every day! :)

It’s kind of a bummer because the valve lash issue sounded like it could be the source of my problems. I haven’t noticed the starting getting any easier after I replaced the gas with fresh. In fact, the motor doesn’t want to turn, even after replacing the starter. So far the only thing that works is manually turning the engine to just past compression. That seems to give the starter enough of a run up to get past the next compression. I’m starting to wonder if something is bent somewhere…
Also, if it does have the ACR and if it sticks. It can and usually does bend the exhaust pushrod. Steel tipped aluminum. YouTube has a number of videos on the subject.
 

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Thanks Cannon! Yep - I figured it out when I saw the word “hydraulic”. Learning something new every day! :)

It’s kind of a bummer because the valve lash issue sounded like it could be the source of my problems. I haven’t noticed the starting getting any easier after I replaced the gas with fresh. In fact, the motor doesn’t want to turn, even after replacing the starter. So far the only thing that works is manually turning the engine to just past compression. That seems to give the starter enough of a run up to get past the next compression. I’m starting to wonder if something is bent somewhere…

I fought this problem on a Courage 20 hp for a while. It had to have a good bit of head start to overcome compression. I checked and adjusted valves ( these are adjustable on Courage). Finally found out the battery was weak. Replaced it with a 300cca battery and problems went away. Don't rule out battery.
 

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Discussion Starter · #9 ·
I fought this problem on a Courage 20 hp for a while. It had to have a good bit of head start to overcome compression. I checked and adjusted valves ( these are adjustable on Courage). Finally found out the battery was weak. Replaced it with a 300cca battery and problems went away. Don't rule out battery.
Thanks bill Shannon. That’s where I started with all of this: checked ignition system, replaced the starter, etc. I have noticed that even when I line up the piston to TDC sometimes the battery doesn’t have enough guts to overcome compression. I have had to jump the battery with my Jeep on a few occasions.
 
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