312-8 PTO Lever not staying down, deck takes long time to spin up, and engine poor performance,

[TC10284 113]

Picked up an older 312-8 last weekend. Has the older style Kohler 12HP cast iron, narrow rear tires, and reflectors on the rear instead of taillights. I would post the model number but there isn't one. The label in front of the seat is completely white. No serial # either. 

 

My problems that I need to address are mainly these three:

 

Engine poor performance - I have to leave the choke pulled out maybe 15-25% for it to run solid. Otherwise, it acts like it's not getting enough fuel or out of fuel. I put about 1gal of fresh gas in it. Prior, the tank was close to empty. I noticed a long crack in the top of the fuel line, but it does not appear all the way through when I squeeze it. Again, it runs well when choke is pulled out just a bit. Have tried adjusting the three screws on the carb, but so far have not noticed much improvement. 

 

PTO engage lever won't stay down. Tried to adjust the part of the lever that goes on the threaded rod and it is rusted stuck. I had to use a little force to get it sort of unstuck, but it won't go far. This is when the engage lever began to pop back up on me. I can't tell where anything is bent though. Not that much force was used even still. 

 

Deck takes a long time to spin up. Probably related to the above. Belt is tight on mule drive. Already checked that.

 

Pictures:

https://imgtc.com/a/7kbkbk1 

 

Edited December 4, 2018 by TC10284

[953 nut 63,187]

The first step will be to clean the fuel tank, replace the fuel line and add a filter. The carburetor should be soaked in carb. cleaner and rebuilt and use only ethanol free gas.

[oliver2-44 11,076]

Regarding the choke issue you may have an air leak, thereby the engine wanting extra fuel to go with the extra air.  With the engine running spray some carb cleaner or WD40 around the carb throttle shaft, the carb to block base, and the air clear to carb.  If engine revs up you found your air leak.  i

[TC10284 113]

Thanks guys. 

 

Any thoughts on the PTO lever issue? I'm a little concerned about that one as I haven't ran into that one yet and am afraid I might have caused some of it. 

[gwest_ca-(File Mod) 11,869]

Sounds like the classic pto clutch slipping.

You should pull the pto assembly off and check the clutch lining thickness. Wear will expose the rivets and ruin the pressure plate. While off work some fresh grease into the large needle bearing. You don't want any extra as it can work it's way the the friction material and ruin that.

Free up that threaded trunnion on the pto rod so it threads easily. It needs to be tightened up so when the pto is applied the handle snaps over center with a bit of authority. Hard to describe the proper tension but you want the deck to speed up immediately and not slip under load. Sometimes the clutch will emit a high pitched squeal like a belt when it slips. You don't want that.

If you have got this far you need to reinstall the pto brake. With engine not running apply the pto clutch. Slip a business card between the pulley and the brake pad. Hold the pad tight to the pulley and tighten the bolts. Remove the card and release the pto clutch.

 

Garry

[TC10284 113]

2 hours ago, gwest_ca said:

 

 

2 hours ago, gwest_ca said:

Sounds like the classic pto clutch slipping.

You should pull the pto assembly off and check the clutch lining thickness. Wear will expose the rivets and ruin the pressure plate. While off work some fresh grease into the large needle bearing. You don't want any extra as it can work it's way the the friction material and ruin that.

Free up that threaded trunnion on the pto rod so it threads easily. It needs to be tightened up so when the pto is applied the handle snaps over center with a bit of authority. Hard to describe the proper tension but you want the deck to speed up immediately and not slip under load. Sometimes the clutch will emit a high pitched squeal like a belt when it slips. You don't want that.

If you have got this far you need to reinstall the pto brake. With engine not running apply the pto clutch. Slip a business card between the pulley and the brake pad. Hold the pad tight to the pulley and tighten the bolts. Remove the card and release the pto clutch.

 

Garry

 

Thanks! I'll check the clutch thickness. I do recall seeing the PTO brake being pretty far away from the spindle already. I have a couple new brakes already. 

Will add some fresh grease to bearings also. 

 

What's the best way of freeing up the rusted trunnion? Already tried some pb blaster so I'm guessing heat this time?

[gwest_ca-(File Mod) 11,869]

If you have moved the trunnion a bit just keep working it back and forth while flooding it with PB. It should come. If it were mine I would run a thread die up to the trunnion and then work at getting the trunnion off. Then chase the threads the full length with a die. Never-Seize will prevent that from happening again. I'm thinking it is 3/8" coarse thread.

 

Garry

[Lee1977 7,463]

Check the out side c-clip on the short shaft that is attached to the loop. They some times come out of the groove. Proper adjustment is not possible when this occurs. You may need a new C-clip, also check the grove in the shaft I have had to replace both a few times over the last 41 years.

[gwest_ca-(File Mod) 11,869]

When most retaining rings are made they are stamped. If you look close at it one side has rounded edges and the other side has sharp edges. In the pto application you want the sharp edges facing out so it registers in the groove better and less chance of the stub shaft being pushed through the ring.

 

Garry

[AHenry014 127]

I would definitely recommend rebuilding/cleaning the carb.  Running best at half choke generally means that the main jet is semi-plugged.  From your pictures, i can see some orange sealant on the bowl.  The rebuild kit is <$10 and its super easy to do on these singles.  

 

As said before, i would throw some new fuel line on there with an inline filter at the same time.  

Edited December 6, 2018 by AHenry014

[TC10284 113]

How do you remove the PTO shaft (arm) from the tractor? 

Edited December 8, 2018 by TC10284

[gwest_ca-(File Mod) 11,869]

Just a cotter pin #12 in the back end.

 

Garry

 

[TC10284 113]

Right, I can see it, but I cannot access it easily. 

Is there a trick? 

[refracman 167]

You shouldn't have to remove it to clean it up and get the trunion to move.

Do you have a good wire brush? use it and get busy on the threads on both sides of the trunion, even better is you have one on a grinder or dirll! leave the trunion attached to # 17 for as long as you can to get the treads cleaned up. also clen up the pully where the deck drive belt goes. she looks a tad rusty there too. 

then cover up the pully and belt then soak with PB, let it soak, if you have a way to heat it some, more the better,  once off chase it with a die.

 to adjust it like stated above its a trial and error thing but should take more than a couple of minutes. 

 

on the belt noise, check the mule drive pullys make sure they spin free and same with the deck belt and spindles. 

Some good advise on the run with choke issue, either its a dirty carb ( most likely) or worn throttle shaft.

 

While your at it I would take the cover plate off and check the shifter boot, they are cheap enough and good insurance as it looks like she has been out in elements for a bit

 

 

 

 

[peter lena 9,579]

the trick is to remove the battery, and clear up the problem. with battery out , now you can see the very sloppy stop/fit of the lever. notice how the rod has been grinding against the fuse holder area? local hardware store has steel and nylon washers to fill in end gap fit near battery . that has to be solid and smooth to properly work. your carb is long overdue for a rebuild, lack of basic maintenance is evident, LUBRICATION ? WHATS THAT? the rust coated pto and related areas also need clean up. That pto trunnion should be free to move. what I am seeing is a basic starting point to recover this horse, this is the first area that I change over on a recent purchase. its frustrating because , EVERYTHING HAS BEEN NEGLECTED , as you start to get things moving/ working , it gets much better. I will send you a few pictures, to clear up my view of this common problem. hang in there , pete  

[TC10284 113]

My issue is that I cannot physically get to the key with pliers or needle nose pliers (part 12 in the diagram above) at the end of the shaft to remove it. Maybe I don't have the right kind? 

 

I am removing it because re-threading the threads, along with WD40/PBBlaster did not help. It was so rusted that it snapped the rod in two at the threads when trying to free up the trunnion. I have an extra one on a parts 520H that is is good condition, but am having difficulty figuring out how to get either one of them removed. 

Edited December 9, 2018 by TC10284

[peter lena 9,579]

some pictures of repair and upgrade,

[peter lena 9,579]

first picture shows ,reason to remove battery, it also shows shimming washers on lever end , that must be snug ,to operate properly. Second picture shows heim joint in place of trunnion fitting, constant smooth/solid ,moveable joint to pto engagement point. Third photo shows 3/4" 2 bolt flange bearing to stop steering column slop.fourth photo shows clearance to lever rod near fuse frame , no rubbing and smooth free movement. I realize that to the w/h purists this simply cannot be done. along with the fluid film anti rust film on related surfaces. I also use cable wrap to secure and run wire. having recently done this , I find it to be a base line initial service, that make neglected areas come back to life with a like new solid smoothness, that's only me , pete  

[TC10284 113]

On 12/9/2018 at 10:23 AM, peter lena said:

first picture shows ,reason to remove battery, it also shows shimming washers on lever end , that must be snug ,to operate properly. Second picture shows heim joint in place of trunnion fitting, constant smooth/solid ,moveable joint to pto engagement point. Third photo shows 3/4" 2 bolt flange bearing to stop steering column slop.fourth photo shows clearance to lever rod near fuse frame , no rubbing and smooth free movement. I realize that to the w/h purists this simply cannot be done. along with the fluid film anti rust film on related surfaces. I also use cable wrap to secure and run wire. having recently done this , I find it to be a base line initial service, that make neglected areas come back to life with a like new solid smoothness, that's only me , pete  

 

Is there anything that needs to be removed to be able to access the lever besides the battery?

[peter lena 9,579]

no the battery will give you access. You will be looking at the end of lever arm as it comes thru the flat cam and bracket support. notice the play at the angle, easy to pull the cotter pin and add washers to eliminate that play. That will also tighten up the outside lever . at right side of dashboard area. I use both steel washers and nylon washers at bracket support area, I use synthetic grease /lube at all moving points. makes it work smooth and solid. by the way the # 13 spring ,witch hooks onto the back side of the fuse holder area , is holding your lever arm in place. looking at the loose end of the arm, just fill in the gap to make it snug . this is fairly easy, having done it and related areas will make it better. I just added the other pictures because its a very good area to correct. any other questions just ask , pete

[TC10284 113]

Was finally able to work on this without sinking into the mud (not literally). Was able to get the PTO rod replaced. Didn't have time to test it before it got dark though. 

[TC10284 113]

Does anyone have a PDF or link for the factory jet and idle screw settings for the carb on this 312-8? 

 

Pics of the carb can be found here:

https://imgtc.com/a/7kbkbk1

 

I may just need to take it off completely and have it cleaned/soaked.

I could only get it to run for maybe 20-30sec with squirting fuel in the carb. I have some replacement fuel line to replace that when it isn't so nasty and muddy out. 

Edited December 22, 2018 by TC10284

[tunahead72 2,593]

My internet isn't working well right now, so I can't get your photos to load in this lifetime...

 

You should be able to find an owner's manual for your engine in the Manuals section here on RedSquare (Kohler K-series).  Initial carb settings depend on which carb you have, either a Kohler/Carter with both a high and low air adjustment, or a Walbro with either one or two air adjustment screws.

 

Either carb will have a main fuel needle.  You should at least remove that and clean it thoroughly, including any tiny air holes you might see along the shaft.

 

[wallfish 18,792]

From the Kohler manual. Suggest you remove the carb and, at minimum, clean it.