Simplicity Disaster

Mower trouble? Are 2-cycle engines the bane of your existence?
bill25
Posts: 2583
Joined: Thu Oct 31, 2013 2:20 pm

Simplicity Disaster

Post by bill25 »

Starting a parts list for the Simplicity disaster.

Potentially need a carb rebuild: (Wonder what the difference is)
68 bucks plus shipping
https://www.jackssmallengines.com/jacks ... r/2475703s - That is expensive.
or 16 bucks shipped:
https://www.amazon.com/Yunstal-Carburet ... +ch23+carb


Trans linkage rod:
https://www.jackssmallengines.com/jacks ... /1716470sm
Supposed to have this too:
Simplicity 1960518SM USE 703826:
https://www.jackssmallengines.com/jacks ... ray/703826

Engine parts:
This is John Deere. Don't use this:
https://www.partstree.com/parts/kohler- ... -4-24-525/

Updated with the Simplicity Engine Number:
https://www.partstree.com/parts/kohler- ... -4-24-169/
May need 20, 21, 22, 24, 25. Definitely need 21
21 - Kohler Engines 24 089 02-S - SPRING, VALVE - $5.42
Also:
Kohler Engines M-640034-S - SCREW, FLG M6X1.0X34 - $1.59
Kohler Engines 24 153 30-S - O-RING (YELLOW), VALVE COVER - $5.12
Last edited by bill25 on Mon Nov 26, 2018 1:17 pm, edited 1 time in total.
kevm14
Posts: 15227
Joined: Wed Oct 23, 2013 10:28 pm

Re: Simplicity Disaster

Post by kevm14 »

bill25 wrote:Potentially need a carb rebuild: (Wonder what the difference is)
68 bucks plus shipping
https://www.jackssmallengines.com/jacks ... r/2475703s - That is expensive.
or 16 bucks shipped:
https://www.amazon.com/Yunstal-Carburet ... +ch23+carb
One kit is genuine Kohler and the other is some other aftermarket brand.

Sort of meet halfway in the middle with a Kohler kit on Amazon for $43.

https://www.amazon.com/Kohler-24-757-03 ... s=2475703s

Probably the way to go. I see a needle in that pic, unlike the other two.
kevm14
Posts: 15227
Joined: Wed Oct 23, 2013 10:28 pm

Re: Simplicity Disaster

Post by kevm14 »

bill25 wrote:Supposed to have this too:
Simplicity 1960518SM USE 703826:
https://www.jackssmallengines.com/jacks ... ray/703826
Does that snap on the bottom and hold the rod into the axle speed selector?
kevm14
Posts: 15227
Joined: Wed Oct 23, 2013 10:28 pm

Re: Simplicity Disaster

Post by kevm14 »

bill25 wrote:Engine parts:
https://www.partstree.com/parts/kohler- ... -4-24-525/
May need 20, 21, 22, 24, 25. Definitely need 21
21 - Kohler Engines 24 089 02-S - SPRING, VALVE - $5.42
Also:
Kohler Engines M-640034-S - SCREW, FLG M6X1.0X34 - $1.59
Kohler Engines 24 153 30-S - O-RING (YELLOW), VALVE COVER - $5.12
Not bad on the prices.

I guess I would recommend a new spring obviously. I don't know if you need to do stem seals and if they can even be done with the head on the engine. So probably skip 20. But probably 22, 24 and 25 just to make those pieces all new.

Rocker screw. Not sure if the rocker is damaged. Could get a new pushrod. Not suggesting all of this, just naming things.

Taking the head off is something to think about actually. It looks pretty easy, and you could essentially rebuild it on the bench and drill that bolt without worrying about shavings in the engine. So you'd want a head gasket unless you wanted to be Sloppy about it. Old side valve Briggs stuff could get away without replacing the head gasket, for whatever reason. I'm sure Kohler would also have you get new head bolts....so think about how much of this makes sense to you.
bill25
Posts: 2583
Joined: Thu Oct 31, 2013 2:20 pm

Re: Simplicity Disaster

Post by bill25 »

Does that snap on the bottom and hold the rod into the axle speed selector?
It snaps on to the bottom to stay on the transaxle cylinder. The speed selector is turned in and is held that way.
bill25
Posts: 2583
Joined: Thu Oct 31, 2013 2:20 pm

Re: Simplicity Disaster

Post by bill25 »

kevm14
Posts: 15227
Joined: Wed Oct 23, 2013 10:28 pm

Re: Simplicity Disaster

Post by kevm14 »

Now that I have confessed in person I can document it here.

While we were trying to get the broken valve cover bolt out of the head, I decided to apply heat, because that is often called for and can in fact make the difference between success and further breakage. I heated the corner of the head around the broken bolt. We rigged up a shield for the throttle and choke cables....but neglected to think about the valve springs. I believe that some heat made it past the side of the head and blasted the exhaust valve spring. It weakened the temper, though we had no indication of this. After the hole was tapped and the new valve cover and fuel pump was installed, after 10 minutes of running (maybe less), it must have loosened up enough to allow the rocker to slip off the valve and put a wicked side load on the retaining bolt. It snapped clean off in the head. So that was my bad and I feel bad about it. The good news is, it takes the mystery away from the failure...

Lesson learned: properly evaluate what you want to shield from heat. I did not expect that much heat to blast on the valve spring and, similarly, would not have expected the spring to be so sensitive to mostly indirect heat.

So hence the new valve spring and whatever associated hardware is required (retaining stuff, obviously the bolt, etc.). We'll have to drill and see if we can extract the bolt. I am hopeful since it broke in bending - it shouldn't be completely jammed in the head. Key word "shouldn't."

I also want to document my thoughts on the carb. We pulled both plugs and cranked it over once or twice with the fuel pump fully connected. It appears that the pump was overpowering the carb needle and seat and fuel was being dumped into the engine while cranking. That is NOT normal, if there are no plugs to create compression. With no compression, there is no vacuum. With no vacuum, there should be no draw of fuel through the jet. It wasn't being drawn - it was being pumped because the needle and seat was unable to seal off. We saw evidence of this early on with gas all over the place. Just for clarity's sake, the job of the fuel pump is to keep the float bowl full. The amount of fuel drawn into the engine is metered by passages and jets within the carb, based on the vacuum signal and air velocity of the intake air itself. The carb is solely responsible for admitting fuel into the engine to run it.

All that said, I wonder if the fuel pump WAS working fine, and the issue was actually the carb the entire time. Or, perhaps it actually needed a new pump AND a carb service. One thing is for sure: replacing fuel pumps and rebuilding carbs are both very common necessities on small engines, so there is really nothing abnormal about that.

I do agree with fixing the valvetrain and analyzing the results. However, I suspect that the new pump is actually working better than the old pump. I also suspect there was an underlying carb issue that the new pump basically uncovered. I don't think the carb suddenly started malfunctioning. I feel pretty confident that the engine would benefit from a carb cleanout and rebuild. Between that and the fuel pump, it would most likely solve the original issue and probably run better overall. Excess fuel in the engine isn't good as it can wash the oil off the cylinders promoting excessive cylinder and ring wear, and even make its way down to the crankcase diluting the oil, which is also bad.
bill25
Posts: 2583
Joined: Thu Oct 31, 2013 2:20 pm

Re: Simplicity Disaster

Post by bill25 »

http://www.kohlerenginesparts.com/PartS ... 7c%7e39185

Get 4, 5, 6, 7, 8, 14, 15, 19, 18, 17, 3, bunch of 2,

Spring and pieces: 4 - 1.50, 5 - 1.80, 6 - 5.12, 7 - 3.98, 8 - 7.15
Push Rod: 14 - 3.21
Head Gasket: 15 - 29.42
Rocker stuff: 19 - 1.50, 18 - 1.50, 17 - 8.12?
Valve cover gasket: 3 - 4.83
Valve cover screws: 1.50
$74.13 with 4 Valve cover screws
bill25
Posts: 2583
Joined: Thu Oct 31, 2013 2:20 pm

Re: Simplicity Disaster

Post by bill25 »

Kohler Service Manuals:

https://kohlerpower.com/en/engines/manuals

Search CH20
bill25
Posts: 2583
Joined: Thu Oct 31, 2013 2:20 pm

Re: Simplicity Disaster

Post by bill25 »

Ordered the parts minus the head gasket. Added an extra spring. Shipping was like 5.95, tax 3.49, no not a huge deal for another order as I am not getting gouged for shipping. Total cost $59.27.


For info, Carb kit - 71.95!!!

http://www.kohlerenginesparts.com/Catal ... 755?page=1
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