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steve-wis

Help! Kohler ch18 carb

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steve-wis

Hello!

Going over the Agco Allis 918, doing a few things to be ready for next winter. I serviced the hydro, changing the fluid to dexron VI and a new filter, went over the blower, new belt, and now to the engine.  I had to run with choke partially out to blow snow, but it ran beautifully with the choke out like that.  Today, I pulled the carb and cleaned it up.  I did NOT split it because I don't have a gasket kit or rebuild kit.  I did remove the shut-off solenoid, removed the high jet behind it and cleaned it up, using torch cleaning tool, gum-out cleaner, and compressed air.  Also pulled the low speed jet and cleaned it.  Reassembled the thing and the tractor runs just the same, needing partial choke to run smooth.  Pics are of the carb, and the last two are with the engine running showing how much choke it needs to run smooth.  I did NOT drill the high jet any bigger, just cleaned it good.  What is next?  I assume I am correct in thinking the brass slotted jet next to the shut-off solenoid is the low speed jet?  Adjusting it in or out makes no difference in how it runs.  The last two pics are with the choke in the same position, the last one is a different angle.  The fifth pic is an accurate look at the choke when it is running ok.

 

Any advice is, as always, appreciated!

Steve

 

 

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Edited by steve-wis

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Alltractoredup

Looking at the pics, I notice right away the carb still looks dirty, at least outside.  It does not take much to get a tiny bit of gunk on your finger and back into the carb.  I would clean outside with carb cleaner and pipe cleaners very well, and then dig into the insides.  

As you mentioned. You do not have a gasket kit, but I would strongly consider tearing it apart and rebuilding it in a human surgery room ready type area.  Replace gaskets with new set.  Carbs are just finicky sometimes.

Good luck!!

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ShaunE

In the download section is a Kohler carburetor manual.  I have been through mine in every direction.  It is very finicky when it comes to dirt.  Disassemble, ultrasonic clean & replace every O-ring & gasket in it.  Including the two on the bugle shaped fuel shut-off solenoid.  You may be able to "match" the sizes up at a hardware store to save money but that's up to you & how many times you want to take it off & apart until you finally get things "kind of right".

The emulsion tube is sandwiched between the two halves & make sure you check it good with your torch tip cleaner.  I had a fibrous  obstruction that resembled a piece of the gasket in mine.  Ran great for two seconds, then like crap.  I've also replaced the choke assembly on mine as the small spring will eventually wear out causing the choke to not fully close causing a very hard start.

 

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steve-wis

The first four pics were before I cleaned it up.  I did clean it with carb cleaner before I started to take it apart and am pretty confident it was clean, as far as I went.  I will probably need to buy a rebuild kit and do it completely.  It seems like the fuel that is going into the throat of the carb as it is running is not a steady feed but more erratic, maybe the float is set a bit lean?  Or, still crud inside where I didn't go.  Any numbers for a carb kit for this?  It is a 1994ish agco allis 918 with Kohler ch18.  The engine numbers are long gone from the stupid kohler sticker so I have nothing to start with except that it is a keihin single barrel carb.  Suggestions?

Steve

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ShaunE
2 hours ago, steve-wis said:

Suggestions

 

3 hours ago, ShaunE said:

In the download section is a Kohler carburetor manual

 

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LMichaels

One not relating to the carb. GET THAT DEXRON VI OUTTA THERE!!!!!!! It is FAR too thin to do the job your transaxle needs. Use Dex III or IIIH, Type F or transhydraulic fluid but DO NOT run it with Dexron VI you will ruin the trans.

Yeah I know the bottle says "compatible" trust me on this it's NOT fully compatible. Even in GM (GM actually developed the VI specs) there are service bulletins noting to NOT use it due to transmission damage.

 

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steve-wis

The dexron VI is in because I only use the tractor in the winter, and the fluid that was in it, which is the recommended fluid, got too thick and I was burning drive belts in the winter when first starting the tractor.  I am going to run it to start this winter and see if the problem is gone.  It was recommended by another member on here.  Guess we'll see how it works.  

As I work thru the Kohler manual for carbs, I am constantly reminded why I so much prefer Briggs engines.  The kohler is fine when it is running well, but a real pain to find anything for, and most parts are at least twice as expensive as comparable Briggs.  But hopefully I will find what I need.  The carb kits listed in the manual have low speed jets, but no high speed jet to replace the one in the carb.  I am assuming this is so Kohler can gouge another $35- $50 for the high speed jet, which from what I am told is most always a problem and should be replaced.  I could drill out the one I have bigger if all else fails.

 

Steve

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LMichaels

You're WAY better off using a synthetic like Mobil 1 trans fluid which is NOT a Dex VI fluid. Believe me you WILL ruin that trans with VI in there. Definitely not meant for these types of application. Everything from the additive pack to being WAY WAY too thin to start off will wreck your unit. Seen enough of damages from using this stuff because people think it's backward compatible to Dex III. If you're having cold weather issues tearing up belts it is NOT due to fluid issues. You have other issues.

If you feel it is fluid and want to use a good fluid that will not ruin your trans try this one in it https://www.valvoline.com/our-products/automatic-transmission-products/import-multi-vehicle-automatic-transmission-fluid

I know it says "Import" but understand the imports it's made for originally spec'd Dexron III/IIIH and since Dex III is no longer a single "viable" spec in the US this is specified for most older imports where the original DexIII is not present.

I have used this fluid countless times for specifically Dexron III requirements with outstanding results. Whoever recommended to you to use VI did you no favors it will wreck it (maybe not the first season but it will wreck it). Until you've seen the damages DexVI causes in a Dex III application you'd never believe it 

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MikeES
On ‎6‎/‎10‎/‎2019 at 5:33 PM, steve-wis said:

got too thick and I was burning drive belts in the winter when first starting the tractor. 

I don't know how this is possible?  Most all of us here are using the Dexon III or Light Hydro-Trans fluid at 30F below 0, with no issues.  Do you push in the clutch when starting?

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steve-wis

Always push in the clutch, start and let it run a minute or two and then let out the clutch, will smell belt slipping for a minute or so.  Has done this since I got it.  Only when it gets down to 0 or below, but that is a lot of the time.

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PhanDad
4 hours ago, steve-wis said:

then let out the clutch, will smell belt slipping for a minute or so.  Has done this since I got it. 

Very strange.  Is the clutch pivot free and not at the end of it's upward travel?  Correct size idler and belt?  Idler in top most hole as in this pic:

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I'd think one of those is the issue.  

If you've never taken the pivot bolt out and made sure the spacer is rust free and well lubricated, I'd bet that's the issue.  Especially if the prior owner never used the clutch (starting or otherwise).  With the pivot spacer not properly lubricated, once the clutch is depressed, I've found the system won't put proper tension on the belt.  

 

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PhanDad

@LMichaels

I'm running Dexron in my Hommie Vickers hydro - it's the original OEM recommended fluid.  Specifically I've been topping off the system with "DX-III/M ATF" ("which meets DEXRON-III/MERCON performance requirements").   It appears it's compatible with the older fluid (maybe there was a "II" version as well?).

Apparently, when my personal supply of this fluid runs out, I shouldn't use the "VI" version.  Is the fluid you recommend above, compatible with what I'm currently running?  Or do I need to do a drain, run a bit, and drain again to get rid of most of the existing fluid?

But first, I'm going to hit the local "old school" auto parts store and see if any dusty bottles of Dexron III are still on the shelf.  sm01

 

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LMichaels

Do not under any circumstances use Dexron VI or Dex VI "compatible" fluid in ANY piece of equipment you care about because it will turn into a pile of junk in a heart beat. It's NOT that the fluid is junk it's NOT, it is that it is not the proper spec (weight, flow, friction coefficient, etc) for use in our equipment.

Be VERY VERY careful of buying any trans fluid as more and more are adopting the Dex VI spec and many people are being unpleasantly surprised when their transmissions fail because of it.

If in doubt buy this https://mobiloil.com/en/automatic-transmission-fluid/synthetic-atf

Expensive but worth every penny. Or the link for the Valvoline Multi Vehicle Import in the blue jug. Again a little costly but cheaper than M1 and nearly as good. It too meets the very strict requirements of Dexron III (don't let the import label fool you) Toyota, Nissan and Honda all used the Dexron III until GM dropped the designation so they had to design their own spec which matches Dex III.

This is the best advice you're gonna see all day!

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steve-wis

Bill,

I will check the linkage and arm to be sure they are correct and free.  They seem to be working well but I have not taken it off and lubed it so I will.  Good suggestion, thanks!

Steve

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