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Old 12-05-2012, 07:02 PM
LewisL230 LewisL230 is offline
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30hp Kohler Rebuild

Well my season is over so it's time to tear down. The motor is a ch750 30hp Kohler on a 2006 exmark. It has about 1600 hrs on it. I bought it from another LCO. It had been sitting a while and when I got it it ran great, with just normal tune up. Well after last winter the problems started. At this point it uses a quart of oil ever 1.5 to 2 hours of running. It hasn't been that bad until recently so I decided to limp it the last month instead of trying to do a big rebuild during the season. So here I am. I plan to pull the motor off and put new rings, new valve seals, new reed valve, new governor shaft seal, and new gaskets and filters. My question is is there anything else I need to do while its apart. Should I get the valves and seats surfaced? Should I run a hone through the cylinders or leave them be? Just looking for some experienced advice. I've built v8's my whole life but need anything this small.
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Old 12-05-2012, 07:44 PM
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BigFish BigFish is offline
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Absolutely get the heads/valves done!
You should go to the Kohler website and download a free service manual.

I always use a brush type hone to deglaze/condition the bore. But you also need to check for excessive wear.
If you've done v-8s etc, then you know what ya gotta do.
Get the service manual.
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Old 12-14-2012, 04:57 PM
Oldtimer Oldtimer is offline
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I am assuming the engine is not blowing white smoke, just consuming oil.

Before you do anything, check the crankcase vacuum. The gauge has a cone shaped tip that goes into the dip stick tube. You should see a -10 psi. If he needle bounces back and forth the problem is head gaskets.

Replace the head gaskets and head bolts.

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Old 12-14-2012, 05:00 PM
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piston slapper piston slapper is offline
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Quote:
Originally Posted by Oldtimer View Post
I am assuming the engine is not blowing white smoke, just consuming oil.

Before you do anything, check the crankcase vacuum. The gauge has a cone shaped tip that goes into the dip stick tube. You should see a -10 psi. If he needle bounces back and forth the problem is head gaskets.

Replace the head gaskets and head bolts.

Oldtimer
Normal crankcase vacuum on a Command twin is 2psi...
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Old 12-14-2012, 05:30 PM
Oldtimer Oldtimer is offline
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Normal crankcase vacuum on a Command twin is 2psi...

You are right.

Just a negative needle movement on an analog gauge is indication enough.

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Old 12-15-2012, 10:04 AM
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Richard Martin Richard Martin is offline
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Yeah, 1600 hours on a Kohler is just getting good and broken in. I'd definitely look at the head gaskets before a rebuild. If you do a compression test I'd be willing to bet that one side is significantly lower than the other side. Pull both spark plugs and set the throttle wide open. If both sides have about the same compression then do a leak down test.

Always do diagnostics before you spend a dime in repair.
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