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Sovereign Problems


Orange Alpine

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The tractor is an Agco Allis 918H with power steering.   It has been re engined with a Kohler Vee Twin and works quite well.  Last week problems popped up and I am at a loss as to the cause (or causes).  I first noticed a loss of steering aid.  Then forward speed dropped, when I tried to increase speed, the speed control lever would stop midrange of forward speed.  The stop was so dramatic I stopped the tractor to see what was stopping or binding the linkage.  Strangely, the speed control lever would advance all the way.  But when I resumed operation, the stop returned.  After a while, the stop disappeared, but I had to put the control into the fastest position in order to move forward.  Steering got very difficult with lots of play and very little power assist.  When I decided to quit for the day, I stopped with the tractor with the foot brake and shut off the engine.  When I released the brake, the tractor rolled forward several feet.

I have determined there is a small leak in the small power steering hose.  I say small because I have yet to see any fluid gush out.  I topped off the transmission fluid and tried to drive the tractor and work out any trapped air.  No improvement.  Would this leak cause the transmission problems I have?

Bill

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Hello, Do know if the Hydraulic oil filter has  ever  been changed ? These tractor are over 20 years old  and  seem to run forever .

I have 2 sovereigns one with power steering  and one manual steer.

The oil filter may be the problem, One time I used an STP brand filter that was supposed to  be equal to the simplicity filter  ,

the STP filter did not allow the proper flow  and was quickly replaced , It's been fine since.

Thanks Ken in Mi  

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I think so, the filter appeared to be new when I bought the tractor.  But maybe it was just wiped off real good.  Will give that a go.

Thanks for the tip.

Bill

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If you use the foot brake, make sure the tension pulley for the pump drive is fully releasing. The belt could be slipping on the pump drive, giving you less hydraulic pressure which could be the reason for all your issues. There is an adjustment on the tensioner so the correct amount of tension is on the belt. I’ve had to adjust my tensioner on both of my sovereigns due to belt slippage and stretch.

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As stated above, it could be drive belt tension. Check the pivot bolt assembly; often it rusts up and then doesn’t allow the idler pulley to put pressure on the belt. 
The bolt goes through a spacer and the idler bracket rotates on outer diameter of the spacer. The spacer is held tight by the bolt. The annular space (outside of spacer/inside of bracket hole) needs to be cleaned up and lubed

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Well, the House Guests left this morning so I took a look at the clutch belt and the mechanism.  Looks like new.  No dirt, no rust, easy working with good mechanical clearance.  This tractor had a very sheltered life.

Bought a new filter, installed it and topped off the reservoir.  Backed out of the shed, no steering to speak of and crawled forward a few feet while the control was in the fast position, then stopped.  Would not go forward, backward or move the front wheels.  Pushed it (by hand) up to the storage shed ramp and pulled it in using a Harbor Freight strap come along.  Got it up the ramp and pushed it to its resting place.  Strange fact:  it will not steer when the transaxle is engage but will steer (barely) when the engine is off.  Checked the reservoir, still full.  There is now a leak on the non power input side of  the transaxle.  Appears to be coming out past the gasket. 

Looks like it is final, I am screwed.

Thanks to all for the tips, I was dead in the water.  Now I will buy a new tractor as my wife has been encouraging for the past three months.

Bill

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@Orange Alpine - we don't give up easy here.  The above tips were the "easy" possiblities.

Another possible cause of the binding in the hydro lever is loose BGB bolts; check to make sure they're tight - but that wouldn't totally cause the hydro issues you're having.  

As to the filter you installed - the micron spec is 25; a "better" filter in this case causes issues since the filter is on the suction side of the charge pump.   

As to the loss of hydraulic fluid flow/pressure to run the tranny, hydro lift, and PS, make sure the pins on the valves of the "hydro release" are all the way up so fluid isn't bypassing back to the fluid reservoir.  

If they are up, maybe one of the 2 relief valves are stuck open.  

See this post for detailed discussion of your issue:

https://simpletractors.com/forums/topic/65772-sovereign-issues/

Note in the above posts the issue could be caused by the hydrolift valve or linkage.  

 

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55 minutes ago, Orange Alpine said:

Bought a new filter, installed it and topped off the reservoir. 

Just wanted to stress that it cant be an off the shelf automotive filter from walmart.  As @PhanDad mentioned above the mincron ratings are different from automotive to hydraulic filters. Has to be an OEM Simplicity filter or a direct crossover like Napa carries( or at least used to carry.)

Other than that and the belt tension things & pop up valves sticking, , one would have to take it to a dealership and have some pressure tests done to see whats up really.  Could be charge pump problems, which  can be replaced  relatively easily with another used one if thats the case. Wouldnt be cost effective to buy new parts like that.

 

14 minutes ago, PhanDad said:

- we don't give up easy here. 

Yeah.....     thats sometimes an understatement. When owners give up and sell a tractor like your Agco with power steering cheap, people in here tend to dive on stuff like that like a pack of wolves on a wounded deere.666.

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58 minutes ago, SmilinSam said:

Other than that and the belt tension things & pop up valves sticking, , one would have to take it to a dealership and have some pressure tests done to see whats up really. 

Checking the pressure yourself isn't difficult if you have a 1000# gauge and  adapters/hose/tubing to attach it to the testing port.  In the post referenced above, there is a link to this "Recovered Article" post:

  https://simpletractors.com/forums/topic/65773-sundstrand-pressure-checking-recovered-article/

 

which shows how to do the pressure testing.  If I remember correctly, you only have to connect the pressure gauge to one port (B) since this port shows the charge pump pressure when the hydrolift lever is centered. 

As mentioned in the write up, you have to move the hydrolift lever to the end of its travel (either way works) and let the lift cylinder reach full travel; when it does, the implement RV will lift and you can measure the implement pressure.  

I would think the cost of a pressure gauge and plumbing bits would be cheaper than what a dealer would charge you.  

 

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You probably know this but just checking.

Did you lift the vent pin when filling?  Do you lift the vent pin when checking fluid level?

If not the system is NOT full of fluid.

Edited by MikeES
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Bypass valves per chance?  There is a bracket (for lack of a better word) under the seat that when pushed down will push two pins in.  These are bypass valves and when depressed will not allow the pump to work.  It is possible one or both of these was being pushed down.  If so, the tractor could be brand new and it wouldn't budge.

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Well, I think I have found the problem, but am no less mystified.  Checked the bypass valves.  The rear pin would not move under all the finger pressure I could summon.  The front pin appeared to be a bit lower and very easily moved all the way down.  I have removed the valve.  It is all the way down and I cannot move it up.  I held the exposed lower portion of the pin against a 2 X 4 and pressed as hard as I could.  Would not budge.  I have a twelve ton press, so I am sure I can move it, but need advice as to what is happening and the correct procedure.  Is this the normal action of the valve?  Should I just press it back up and reinstall? 

Bill

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Further investigation has revealed the pin at the bottom of the valve is not connected to the exposed pin.   I now have the pin moving smoothly as it should.  Should the rear valve pin move smoothly?  Also, the chamber under the forward pin is empty.  What does that mean?

Bill 

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A bunch of excitement over very little.  The "problem" was two stuck pins.  One stuck up, the other stuck down.  A bit of Gibbs lube and I got them loosened to the point they would give an audible "click" when pushed down and released.  Reassembled and started the tractor - no improvement.  It will not move under its own power, no steering and I can still push it. 

I'm afraid this is where the adventure has to end.  I'm almost 80 years old and have suffered two near death medical issues that, combined with the years, have compromised my ability to tear into complicated equipment and fix it.  It will go to our son who has an old, nay, ancient Sovereign that could stand to receive some new parts.  So many that he will probably put his rear axle and steering onto this tractor. 

Many thanks to all who took an interest in my problem and offered suggestions.  While none proved to be the silver bullet, they were useful in helping me reach a decision and I am grateful.

Bill

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It is time to hang up the socket wrench.  After a long association with lawn mowers, a 42" Murray deck under a Polaron, building from the ground up a front mounted deck (sweet deck articulation/drive but steered hard) with rear steer that morphed into a front drive/front steer abomination and finally into a walk behind, it is as my wife says, time to get a new tractor that I can mow with instead of work on.  My inability to work more that a very few hours a day weighs heavily in this decision.

Bill

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Smart move Bill. When you spend as much time wrenching as you do mowing, it's time. The newer machines may not be built (or overbuilt as it were) to the standards of the old ones but the comfort and convenience of them can't be beat. Power steer, foot controlled hydros, full suspension, high blade speeds all mean a faster, more comfortable cut. Good luck!!

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