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Tractorholic
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I'm working on a MF 12 hydra speed now, that I found at the salvage yard. I'm putting in a neighbor's HH120 off an old sears tractor, but water sat in his carb and it is rusty and grungy. Two questions: Anybody got an old carb to fit a HH120 tecumseh, and where are the drain and fill plugs for the transmission as well as the hydro oil.

Thanks,
Howard
 

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Tractorholic
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Discussion Starter · #3 ·
How do you check the level of the hydro fluid, is there a 'weep' plug, or do you drain it and pre measure the fill? I've looked through the available manuals and haven't seen much info on this.

Howard
 

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Tractorholic
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In the absence of any information, I added 1.5 quarts of Dexron oil to the Hydo transmission. Right now, the hydro will run for a bit, then everything will quit, then there will be a sound like the hydro is loading up, and the tractor will start to move again. Again, this tractor came home from the salvage yard, so I have no idea what the history is. Does this sound like air in the system? and if so, how do I bleed it out?

Can someone tell me if the freewheel valve should have the long end of the T towards the ground or away from the ground? Or is there another position that should be used?

I would like to drain and refill the axle, but although I've found the drain, I haven't found the fill. There is a plug that nestles behind the hitch plate, is that the fill plug?
 

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Tractorholic
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Discussion Starter · #5 ·
OK, some searching through the archives told me that these systems can be bled, so I began doing that. Now I have ATF fluid leaking from around the forward/reverse valve. Any thoughts on how difficult that might be to repair?

Does anyone in particular work on these old hydro systems?

Thanks,
Howard
 

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Tractorholic
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805 Posts
HowardsMF155 said:
In the absence of any information, I added 1.5 quarts of Dexron oil to the Hydo transmission. Right now, the hydro will run for a bit, then everything will quit, then there will be a sound like the hydro is loading up, and the tractor will start to move again. Again, this tractor came home from the salvage yard, so I have no idea what the history is. Does this sound like air in the system? and if so, how do I bleed it out??
The amount of fluid is in the capacity chart in the owners manual. Or you can fill it to the proper level in the reserve tank.

HowardsMF155 said:
Can someone tell me if the freewheel valve should have the long end of the T towards the ground or away from the ground? Or is there another position that should be used??
If I remember correctly the short end is up, when in freewheel mode, The T is horizontal when driving.
HowardsMF155 said:
I would like to drain and refill the axle, but although I've found the drain, I haven't found the fill. There is a plug that nestles behind the hitch plate, is that the fill plug?
Yes, the refill plug is hidden behind the hitch plate for the rear axle. It's a pain.
 

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Tractorholic
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Discussion Starter · #7 ·
I don't have an owners manual, I've been going by the MF10 manual and the service manual. I haven't seen transmission capacities listed.

This tractor has a pipe plug under the seat, that is what I filled.

I'll try the valve in another position, though I would think that if the system had run for any length of time that the valve must be correctly positioned.
 

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Red Tractor Nut & Diesel Addict
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I have a 67 model that did not have the factory reserve tank. It has a dipstick in the top left corner of the hydro tank box. I've never had to work on mine at all.
 

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Electric Tractors
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5,639 Posts
Hydro tractors
Fluid check, there's a sticker and a sight tube on the reservoir under the seat, if the sticker is not there then about 1/2 full in the tank should be good.
If no tank under the seat, there is a brass screw in dip stick near the free wheeling valve.
Hyd trany holds> 3US qts., Reservoir holds 2USpts. hyd transmission fluid type A
Rear axle and diff holds> 2USpts. gear oil. SAE 90

Hyd oil goes in the tank.
Trany gear oil goes in the pipe plug, beside the Hyd tank. (fill up to the level check plug)

Freewheeling valve points UP (long handle up, short end down) for normal operation.
To push the tractor by hand then the handle points down.
All this info I got from my manuals.
 

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Tractorholic
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Discussion Starter · #10 ·
Ok, Thanks for the information, I was able to fill the actual hydro tank behind the wheel. However, it is still doing pretty much the same thing, running for a bit then a real lack of power. In fact it does seem to do better after sitting a bit. I tried bleeding the air out by rocking the handle back and forth, but it makes no difference. I suppose I can locate and install a filter and see if that helps, in my uneducated opinion there is a lack of fluid flow more than anything else. I just hate to invest too much time and money if this rear end is shot.
 

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Electric Tractors
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You must have an early one, does it have the starter/generator or the ring gear starter?
Maybe try running it on jack stands with the rear wheels up in the air, see if you can bleed the air out.
I think the filter is inside the pan??? I never had mine apart.
 

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Tractorholic
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Yup, the hydro filter is inside the hydro. You must drain it and remove the pan to get to it.
Also, I think the original filter is NLA, but I think someone has found a replacement that works?
 

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Tractorholic
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Discussion Starter · #13 ·
Yes, I think is is a fairly early one. I think I dated it as a 1968 by the serial number. Who knows what the original engine was, someone has tried to install a replacement engine. It was a Tecumseh HH120, but the carb stuck out at an angle towards the back of the motor so that didn't fit. Fortunately, they hadn't cut sheet metal yet so the air cleaner would fit, but the missing air cleaner didn't make me feel to happy about the motor guts. I was going to try fixing the lack of spark with some sort of conversion kit, but conversation with a neighbor turned up a fresher, more ready to run HH120. It really needs a new carb as the old one had sat with water in it, and I'm not sure that sort of thing can be rebuilt. I borrowed a carb from my 12G for a day or two just to see how this motor and axle ran. Now I need to sort out any transmission issues without spending too much money. The hood and grill are in nice condition, and the nose peice is intact. It would be a shame to end up back at the salvage yard with it, so I hope I can get the transmission up.
 

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Tractorholic
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Discussion Starter · #15 ·
OK, some minor progress with mixed results. I finally found the correct position for the freewheel valve by pushing the tractor and moving the valve. When the tractor stopped moving, I had the right position. I spent a few moments driving at various speeds around the yard and things seemed ok, but I still need to go over the trans and make sure everything is OK. Also, there is a major leak at the forward/reverse valve, so I'll need to locate the O-rings and overhaul that.

Also received my carb rebuild kit from Partstree.com today. I've had the carb soaking since Thursday last week, so out it came. I sanded the rust out of the fuel bowl. rinsed things off, then put everything together. Major Kudos to my wife for finding the tiny little washer that OF COURSE fell in the grass and got lost. Mixed news on the rebuild. The engine did fire up and run, could probably do better with some adjustment. BUT....A few minutes after I shut the engine down, the carb started flooding and leaking out the air intake. I disassembled it again, worked on seating the rubber seal on the float needle, reassembled it and still had a flooding issue. Anyone have any insights on how to fix this flooding carb? Also, how does that little spring that wraps around the float axle go on?

TIA
Howard
 

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Tractorholic
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3,097 Posts
Discussion Starter · #17 ·
For all I know it is the needle valve assembly. The kit had a float needle, a replacement rubber seat that had to be inserted into the existing assembly, and a retaining ring. Also, the gaskets and a new idle screw and a main jet needle. As to the float, I shook it and heard nothing sloshing in it so That should be ok. There was also a small spring that wraps around the axle pin for the float, but I can't figure how to get it back on----Plus I've never seen anything like that before.
 

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Elf guardian
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7,712 Posts
HowardsMF155 said:
For all I know it is the needle valve assembly. The kit had a float needle, a replacement rubber seat that had to be inserted into the existing assembly, and a retaining ring. Also, the gaskets and a new idle screw and a main jet needle. As to the float, I shook it and heard nothing sloshing in it so That should be ok. There was also a small spring that wraps around the axle pin for the float, but I can't figure how to get it back on----Plus I've never seen anything like that before.
The rubber seat has to be installed with the groove in it away from the needle. Use a drill bit(blunt end) of the right size, to push that seat ALL the way in.
I don't think you need the retaining ring. That may be the culprid. Same with that axle spring.
If your old main jet needle looks ok use it. Compare the old to new. If you got one of those after market offshore kits, you'll see the difference in the needles.
Also, make sure that the little spring clip that positions the needle on the float tab, is nice and loose on that tab. If it binds at all, it will cause the
needle to land on the flat surface of that rubber seat, causeing the over filling issue.
I pulled my hair out this spring with 3 carbs having the same issue. Finally stopped the leaking The above notes stuck in my mind.
 

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Member
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The spring wrapped around the axle pin has to go back with both ends pointing towadrs the choke end of the carb. There are good instructions on how to put the whole thing back together in the red Tecumseh Service Manual that you can download from the GTtalk Manuals section.

George.
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Tractorholic
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Discussion Starter · #20 ·
OK, sorry for a lack of pictures here, but when I get into this thing my fingers are filthy and I don't want to dirty up my camera. As for the carb, I've worked on the rubber seat some more. What happens is that everything seems ok for 10 minutes or so after I shut the engine down, then the gas starts dripping out of the carb throat. I'm suspecting that the new rubber isn't quite sealing the tank end of the carburetor and is passing gas. It isn't bad enough to choke the engine with it running, but I have to make sure I shut the gas off.

I had time and energy to tackle the transmission issue today. Two O-rings that seal the forward/reverse shaft were leaking and needed replacing. I was able to find replacements at my local hardware store. However, now the shift lever is a bit stiff. There is really a lot of wear on the cam and on the cam shift assembly, maybe I can replace them. Drove it around today after reassembling, it is a bit of a challenge to get the transmission exactly in neutral. It did tool around very nicely, going up and down hills at a fairly steady pace. I drove over the curb at a nice slow pace and the tractor just slowly climbs over the curb. I also stopped the tractor at the base of a small incline on my property and rammed the shift lever forward. The front wheels popped off the ground a bit and the tractor just scooted forward. Now with the major systems working I can move on the replacing all the damaged wiring and the ignition switch.
 
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