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  #1  
Old 06-17-2012, 02:24 PM
mpm32 mpm32 is offline
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Scag STHM loss of power

I have a scag 3 wheel sthm. I was mowing yesterday and the mower started losing power. Turned off the blades and the power came back somewhat. Still not very strong.

I have changed the fuel filter. I also pulled the plugs. The right plug was fouled not oil, just a lot of carbon. Got new plugs, installed them. Started it up but still not running strong. Checked the spark at both plugs, they both have a spark.

No gas in the oil.

Could it be carb related? Not sure what I should look for there? What should I check next.

Thanks in advance for any assistance.
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Old 06-26-2012, 09:52 AM
mpm32 mpm32 is offline
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So I took it in for service. They did a leak down test. The right side, from front failed immediately and the left side failed too but slower.

They suggested repowering which would run about $3,000. I'm not going to do that. I'm pretty sure it's the head gaskets. I'm going to give it a shot changing them myself.

I found this thread; http://www.lawnsite.com/showthread.php?t=334950&page=1

It doesn't look too difficult except I would have to do two. I've done head gaskets on Subarus before. I got the service manual from the link in that thread.

A couple of questions;

- Will I need any special tools?
- Will I need to also replace the valve cover gasket?
- Anything else I need to purchase/replace while I'm in there?
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Old 06-26-2012, 10:02 AM
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piston slapper piston slapper is offline
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Mpm...we still don't know what engine you have...
That's why nobody chimed in to help out a week ago...
Without a model and spec number.....I don't have a clue...
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Old 06-26-2012, 10:31 AM
mpm32 mpm32 is offline
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Ah sorry, I thought I included it in the original post - it's a Kohler Command 22
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Old 06-26-2012, 03:02 PM
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piston slapper piston slapper is offline
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Could be a bad head gasket...
Is the oil clean or filthy?..filthy oil can clog the lifters and make them pump up.
When that happens...the valves can stay open and the pushrods can bend...
Coils are always suspect on the 22 Kohlers... The SAM ignition modules can be bad even with a visible spark...it takes a special spark checker to check these coils..
There are many threads on head gasket replacement procedures on command twins on this site...
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Old 06-26-2012, 03:10 PM
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Patriot Services Patriot Services is online now
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Another K~Com failure, big surprise. If it failed leak down immediately I would expect the tell tale hiss if it were a head gasket. I'm thinking more a burned valve or as Slapper said a gummed up lifter fully extended.
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Old 06-26-2012, 03:25 PM
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piston slapper piston slapper is offline
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Quote:
Originally Posted by Patriot Services View Post
Another K~Com failure, big surprise. If it failed leak down immediately I would expect the tell tale hiss if it were a head gasket. I'm thinking more a burned valve or as Slapper said a gummed up lifter fully extended.
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Kohler Command engines routinely last 5 to 10 years...and 15 years is not uncommon..They can be bad expensive to repair or replace...
The majority of the Command problems on this forum are for engines that are way out of the warranty....

Patriot....did you have a bad Kohler experience....or do you just not like them..?
I realize that these engines are tougher than most to figure out......but that is usually a complaint reserved for Briggs techs........
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Old 06-26-2012, 04:16 PM
mpm32 mpm32 is offline
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The oil is clean. I did notice a pfft, pfft sound once the engine warmed up. It does sound like air coming out of a gasket.

I guess I'll pull it apart and see what I get. I'll order the gasket kits and go from there. I really hope it's just a matter of changing the gaskets. I just use this machine to cut my own lawn. It cut my time down from 4 hours on my craftsman tractor with a 48" deck to 4 hours.

Thanks for the advice.
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Old 06-26-2012, 04:45 PM
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Patriot Services Patriot Services is online now
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That sounds like a head gasket then. You'll find the replacements are better quality with slight design improvement.

Slapper- my dislike of Kohlers stems from their overcomplicating designs for no benefit. I have used Kaw's and Honda's forever and not experienced a fraction of the issues Kohler owners do. I'm also pretty anal about maintenance and catching small problems. Buddies are always bringing stuff to me "to take a look at". One guess the number one brand I see.
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Old 06-26-2012, 05:19 PM
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piston slapper piston slapper is offline
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The benefit of complicated designs are to line the pockets of the knowledgable.
You can't build the most durable engines on the market with simple designs.
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