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hotrodtractor

Kohler Command 18 Carb upgrade

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hotrodtractor
I am noticing that the Command CH18 in my 75th is not making as much power as it should and it bogs going up hill. After further inspection I have notice that my oil level keeps increasing and the oil is thinning out... yes gas/fuel in oil. My research tells me this is a carb issue and most agree just to replace the whole thing rather than clean/rebuild. The $150 does not bother me one bit for a brand new carb. My Question is should I upgrade to the 20 hp carb as basically the 18 and 20 share most same everything minus carb? Maybe I will pick up a couple hp and I need a new carb anyway. Does anybody know the part # for my CH18 carb and then a corresponding CH20 one?

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hotrodtractor
I could also get a worked over carb from lakota racing for a bit more "Kohler Command Re Worked Gas Carb - $230.00 * With your acceptable core * Bore, re-jet, external adjuster, new idle circuit, slide in velocity stack (Picks up 2 1/2 hp)" What do you guys think?

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hotrodtractor
quote:
Originally posted by UCD
You need to click on the edit button (paper & pencil icon) in the original post and you can edit or add to it.
I got the 2nd paragraph to post but for some odd reason it wont take this: "I could also get a worked over carb from lakota racing for a bit more Kohler Command Re Worked Gas Carb $230.00 With your acceptable core Bore, rejet, external adjuster, new idle circuit, slide in velocity stack (Picks up 2 1/2 hp) What do you guys think?"

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Burntime
I wondered the same thing, is it the whole carb, jet, or just a piece of linkage that allows it higher rpm? This is where I glaze over and make girgling noise:D:D:D If anyone can confirm I would like to know too. I have a new ch18 just waiting on the linkage.

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hotrodtractor
yes it just does not seem to rev like my other one (other one screams). I thought at 1st it might be a governor issue as when there is a drain on it (going up hill) it does not seem to recover just bog. Seriously a 18hp should not even notice a little incline. I tried to push into a solid object (tree) and tire spun and did not notice bog... only on hill climb. But then I noticed oil getting diluted... could that happen if the engine is not actually burning all the fuel. For example I could have oil at full mark then run for 30 minutes and it will be 1/4 over full mark. I ajusted and set linkage to match my other one so that's the same

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hotrodtractor
one other thing I noticed is that the choke seems to have little effect on the machine when it's been running for say 10 minutes. On my other command if I pulled choke after she was warmed up she would fuss and run bad. On this one the choke seems to have little to no effect..... hmm maybe I have a choke issue. I checked and the chock butterfly seems to operate with cable as expected? I am stumped hence why i was just thinking a whole new carb as they are cheap

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hotrodtractor
Bob I have the stock fuel pump I am not certain but I think it's a vacu pulse fuel pump. There's no wires so it's not electric and don't think it's a machanical... sorry I am not a engine guru... yet :)

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arnoldir
On my 75th the fuel pump lost one of the check valves, so every time it sat for a few days it lost prime and needed a shot of either to get it started. The replacment included the whole valve cover (think there might have been a design change for gasket issues). It sounds like the diaphram in yours might be leaking gas into the engine. Mine ran very lean when purchased (4+ years in the crate) and only ran slightly better with the new pump. I'd been thinking of reaming out the jets to adjust for the E10 fuel we have in NY, and your info about a suped up carb with adjustability has me very interested. Good luck getting yours sorted out.

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hotrodtractor
remember my 75th has a command not the triad. Carl I know that screw your talking about.... hmmm will look in to that thanks either way that does not explain my gas in oil issue

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hotrodtractor
Not sure I guess I could try changing the oil again and just letting it sit to see if oil level goes up.... I am pretty sure it only happens when running. good question does the command have the fuel shut off selenoid. I know the triad did and the vanguard does as both stuck closed on me and I had to free/clean them to get the engines to run. I think it's also called a antibackfire. I guess it could be frozen open rather than closed if the command has one. I still think it's not burning all the fuel as the engine runs pretty weak and does not purr or run smooth. Yes it has good compression and appeared to run good in the old donor tractor (but I only ran for a couple hrs at most then transplanted to the 75th.) I bet I messed something up when pulled appart (front blower housing) to install the clean out kit.

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BLT
On the pulse fuel pump you have three hoses, one from the tank, one to the carb and the vacuum source. The fuel hoses are easy to trace. The vacuum hose could be ingesting gas from a ruptured diaphragm in the pump diluting the crankcase. I would think you could disconnect that line and sniff if for gas smell. If you smell gas, you need a new pump.

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D-17_Dave
At the rate that gas evaporates it may be tough to "look" for gas in the vacuum line. No more cost than a pump is I'd say try that and see if the problem eliminates itself. If your gas is flowing into the crankcase the carb. may be starving for fuel, this could explain the loss of power.

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hotrodtractor
so I guess a quick test would be to swap the fuel pump? remember I have two identical engines in two different machines. looks to be a couple minute job on the command 2 small bolts hold it on. It appears the pump may have been replaced already on one the engines as one is black and one is silver (aluminum metal color).... anybody know which is the newer black or silver.

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BLT
After reading the whole thread go for fuel pump. My Sunstar was a thorn on starting, staying running, chocking. Replacement pump took care of my problem. You can get genuine Kohler parts now at MAPA.

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