Garden Tractors - Allis 712 K301 problem

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Allis 712 K301 problem

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Garden Tractors
Forum Description: A great place to discuss the Simplicity and Allis Chalmers Garden Models
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=131588
Printed Date: 19 Nov 2024 at 8:26pm
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Topic: Allis 712 K301 problem

Posted By: SnoJetter
Subject: Allis 712 K301 problem
Date Posted: 20 Nov 2016 at 12:10pm

Anybody out there have experience with the Kohler cast iron engines? I've got an Allis 712, K301. With the blizzard that just went through MN, I had her out on Saturday with the blower to clear the snow. Everything was going fine for about 30 minutes and suddenly the motor started losing power. I had her revving at full throttle; when I suddenly lost power, I disengaged the PTO, but it still wasn't revving back up where it should. I back off the throttle to maybe about half and it seemed to smooth out. It wouldn't run smoothly if I tried to go back up to full throttle. Idle was perfect just as always.

I parked it and let it cool down. After an hour or so, I tried again, and it worked perfectly for another 20-30 minutes when the same thing happened. I shut it down again, waited for it to cool, and did it one more time. This time, even right after start-up, it wouldn't rev up to full RPM and ran unevenly at full throttle. Idle and low speed are normal, though.

I parked it in the shop and once it was cooled again, I pulled the head to see if there might be an obvious valve issue or a tear in the head gasket. Gasket looks brand new, very little carbon on the head or block. The intake valve (larger one) is black, but not thick build-up at all; exhaust valve is white - is that normal? The valve seats look shiny and smooth - nothing obvious that might be an issue that I can see.

The only other thing I can think of is a bad coil or something messing with the ignition so that the timing is screwed up; or maybe the spark plug isn't getting enough juice for a proper spark? I'm not an expert on ignitions, so I tend to think if there's something wrong with a coil or something that the ignition will just not work. But this thing runs...just very poorly.

Any ideas? Thanks!

Kyle Sands <>< Brandon, MN

Replies:

Posted By: JoeO(CMO)
Date Posted: 20 Nov 2016 at 1:10pm

condensor

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Posted By: HudCo
Date Posted: 20 Nov 2016 at 7:41pm

we had a 341k this spring that did that. does it sound like it is pinging when it bogs down ? we changed everything done valves bushed the carb if it could be changed or replaced it was . in the end the prob . was to much play in the balance gear shafts so once in a while the gears would try to climb each other. was no money made on that job to figure it out.

Posted By: Bird76Mojo
Date Posted: 21 Nov 2016 at 3:39am

Carb icing up. They sold a kit to address this issue in cold operating conditions.

GB :)

Posted By: jaybmiller
Date Posted: 21 Nov 2016 at 7:06am

I'm liking the carb icing as the culprit. Bad ignition,condensor or coil, should affect low speed as well as high speed and you say it idles purrfect.
It'd be intersting to see the 'carb icing kit'.I'm thinking some kind of heat shroud/ducting to get warm exhaust close to carb ?
One 'oddball' idea... water/ice in the gastank ? After some time..it blocks the feed ?

Jay

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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water

Posted By: Coke-in-MN
Date Posted: 21 Nov 2016 at 11:40am

Condenser failure is most times when hot - they quit or ground out - sounds more like carb problem of restricted gas flow - either filter - flow from tank or water in fuel someplace.

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Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something.
"Challenges are what make life interesting; overcoming them is what makes life meaningful."

Posted By: SnoJetter
Date Posted: 22 Nov 2016 at 8:13pm

Hey folks, thanks for the replies. I haven't tried the condenser yet as I haven't been to a parts store. I fired her up again tonight and blew a little snow until it started acting up; interestingly, it was running fine until I really bit in to a deeper drift and once the engine loaded up, it wouldn't recover. I disengaged the PTO but left the throttle wide open and it didn't act like it was going to die - it just was acting loaded up.

If it was an icing problem, I should be able to squirt fuel into the throat and it should clear up, right? Well, I removed the air filter and did just that. Using a squirt bottle, I fired a little fuel into the carb throat and that just about stalled the motor - so that tells me it was getting too much fuel. I also tried playing with the choke. It was pretty touchy, but I could get it to smooth out some with just a hair of choke, but any more and it would flood out.

With the air filter off while it was doing this full-throttle, loaded up/boggy condition, there was a lot of spit-back through the carb. I stuck my hand close to the throat and it was quickly soaked with fuel. There was also a great deal of smoke or mist that was wafting behind the carb. I discovered there is a "vent" on the (what I assume) is the tappet cover behind carb. It was spewing quite a bit of something...it smelled like burning oil, so I wonder if it was an oil mist coming out of there. Later, after the engine cooled down and I ran it again where it was running normally, at full throttle there was NO spit-back from the carb throat, and NO "mist" or smoke coming from anywhere. This engine does not smoke normally; it's pretty clean burning (either low hours or has had a recent rebuild).

Does that description bring to mind any ideas?

Kyle

Edit: would a timing issue cause the spit-back and abnormal smoking? The timing is all mechanical correct? So if it runs fine for 10 minutes it seems unlikely that it would suddenly starts acting all weird due to the timing going haywire...and then start working correctly again...and then go haywire. Or could it??