Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

  • Announcements

    • Kent

      Sign In or Password Problems?   10/09/2016

      If you can't Sign In, you need to reset your password.  Use the Forgot Your Password link at the bottom of the Sign In screen, and the site will send you an email to reset it. If you have an AOL email account, use the Contact Us link at the bottom of the screen -- AOL is intermittently blocking email from the site.
    • Kent

      Feedback Please!   10/28/2017

      See News and Announcements forum.
Sign in to follow this  
Snojetter

Kolhers & Fuel Shut-off Valves

Recommended Posts

Snojetter

I’ve got 4 Kohler twins – two M18’s and two KT17’s.  Each one requires a fuel shut-off to prevent fuel from filling up a cylinder or the crankcase.  I feel that every tractor I’ve seen at a show that has a Kohler twin has a shut-off as well.  It might be that other motors have this problem, but I’m more familiar with the Kohler twins.  I feel like I was told once that the needle valve seat gets worn and won’t seal properly and the only cure is to get a new carb.  (Obviously, the needle can be replaced, but the seat must not be replaceable?)  I’ve never really thought twice about this and I’ve just lived with the “problem.”  It’s not that big of a deal to turn off a fuel shut-off valve…except when you forget and end up with a couple quarts of gas in the crankcase.

On one of my tractors, if I don’t turn the fuel off even if I’m only shutting the tractor down for 5 or 10 minutes, I’ll get backfire upon start-up.  I’m guessing that has to do with fuel pooling somewhere. On the other tractors, I only have an issue if I leave the fuel on for much longer periods of time (say overnight).

Is my experience pretty typical, or is there an actual fix (assuming the needle isn't worn) beyond a brand new carb where forgetting to shut the fuel off wouldn’t be a problem?

  • Like 1

Share this post


Link to post
Share on other sites
Gary

Good question!  I have a brand new (35hrs old), M18 Kohler, on my restomod 917H.  I also have to shut off the fuel supply, or it will backfire through the carb on a quick restart (5 to 10 minutes).  And this is a brand new engine.

So, if someone out there has a "fix", all help would be appreciated.

Share this post


Link to post
Share on other sites
Snojetter

That's interesting. I suppose an old needle on an NOS engine could have hardened rubber and not seal well.  One thing I was thinking is maybe the pressure from a full (or mostly full) tank of fuel is enough to force fuel past the seal.  I'd be curious if the replacement carbs such as the one from isavetractors.com would have the same problem?

My 912 has a fuel shut-off too, but I always turn off the fuel on that tractor out of habit - no idea if it would leak if I left it on.

Edited by Snojetter

Share this post


Link to post
Share on other sites
Tonyvdb

I have two 7117 with the KT 17 engines and never had a problem with them leaking gas into the base until this spring. Both sat in an unheated shed from November to last week when I returned from Florida. One started fine and have been using it no problem, no fuel shutoff. I went to start the other last night and when checking the oil notice it was way above full. Drained the oil and it was mostly gas. Guess I'll invest in a shut off at least for that one. One has the walbro carb and the other has a kohler not sure which is which but now wonder if one is more prone to leaking.

 

Share this post


Link to post
Share on other sites
Brettw
Quote

Good question!  I have a brand new (35hrs old), M18 Kohler, on my restomod 917H.  I also have to shut off the fuel supply, or it will backfire through the carb on a quick restart (5 to 10 minutes).

I happen to put fuel shutoffs on all of my tractors, but have never had a problem with the Kohler twins.  As it is they need a fuel pump if the tank gets too low.  I put a new M18 in my 7119 about 6 years ago, and have never used the shutoff.  You will get a backfire if you restart quickly, but the M18's did not have a solenoid in the carb, so it really is best to shut them down at idle, not a half or more throttle like the newer Commands.

Share this post


Link to post
Share on other sites
MikeES

I have 3 M20s and 2 Kts and I don't trust any of them.  I know that anyone of them would be fine for months, but they will eventually bite you.   I have a M20 that I turn on the gas, and got a call on my cell phone,  I talked about 30 mins and then went back to the tractor, turn over the engine and BAM hydraulic lock.  Never bothered before when I forgot to close the valve.

 

Share this post


Link to post
Share on other sites
Snojetter

So I'm hearing that the problem isn't uncommon, but also not universal...however, is there a fix?  Or just live with it?

It's been like this for 8 years (as long as I've owned my first 917) and I've only had to change the oil twice due to forgetting to shut off the fuel.  That's not too bad, though not having to worry about it at all would be better.

Share this post


Link to post
Share on other sites
gravey72

The way I understand it is that the fuel pump gaskets are the cause of the problem. I had that problem on my first 7117 in the early 2000's, took it to the local simplicity dealer and that is what the mechanic told me

Share this post


Link to post
Share on other sites
Snojetter

Funny thing (and I'll prove my ignorance here), I had no idea these engines had fuel pumps until this weekend.  I just figured they were gravity fed.  When I tore into one of my KT17's this weekend to clean up all the gunk that had accumulated behind the shroud, guess what I discovered while poking away?  Yup, the fuel pump.  Who knew?  (Probably everybody but me..)

Share this post


Link to post
Share on other sites
Snojetter
18 hours ago, gravey72 said:

The way I understand it is that the fuel pump gaskets are the cause of the problem. I had that problem on my first 7117 in the early 2000's, took it to the local simplicity dealer and that is what the mechanic told me

Does that mean a rebuild of the fuel pump will solve the leaking?

 

 

Share this post


Link to post
Share on other sites
gravey72

I paid to have my original done and did one myself. It solved my problem of fuel mixing in with the oil in the case. Believe it or not I ran that engine for I don't know how long(hours) before I realized I had a problem and that engine is still running like a top today about 15 years later. Many people knock the kt engines and prefer the commands etc but I think the old motors have a longer life

Share this post


Link to post
Share on other sites
Ronald Hribar
Quote

electrically operated fuel shut offs have been coming down in price,still 10 times the price of manually operated.

but are getting smaller as well, Advantage: shut off key and fuel is shut off,

 

Share this post


Link to post
Share on other sites
ShaunE

I have fuel shut offs as well but only ever use them while changing the fuel filter.  Never had a problem with fuel in the oil.  However, all of them had new fuel pumps installed after acquisition.  Also, never had a breather problem either. Knock on wood.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

×