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bigwheel

POWERMAX uphill battle

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bigwheel
I have a 1973 power max that runs good but can barely get up a small hill. Appears to be in the hydro static tranny. fluid is good with a fairly new filter. Is there a good way to check for the pump?Also I recall some discussion about filtration being to fine on certain replacement filters not sure if this is a symptom of that. Any ideas would sure be appreciated

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bigwheel
Thank you, I had just replaced the clutch pulley support brgs (nasty job) because the front brg was shot and the belt was slipping . However I did not replace the belts,because I did not want to uncouple the PTO shaft, the belts seemed ok, maybe a little soft. Certainly not like the new replacement belts sitting on my bench!!. I will sock up the compression spring and see if it helps. Tom R

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bigwheel
I do, however the threaded rod that the spring rides over and set up with a couple of lock nuts is stripped down near the plate in addition the compression spring free length is 1/4 in short to spec , so the 7 3/4 inch setting doesnt work ( not enough load to keep the belts tight) I am able to get the belts tight however unless they need to be tighter than say an accessory drive v belt on an old car for example. Tom R

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StanD
Did you check the bushings & shaft on the lower clutch assembly where it pivets? They are usually worn out along with the shaft which will allow it to give enough that only one belt is doing the pulling no matter how much spring tension you have.

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SmilinSam
What kind of oil filter did you use on the transmission? I ask, because when I had my 720, I used Fram filters and they changed them at that time making them more restrictive. Put a new one on, thinking nothing of it because I had used these for years, and my tractor would harly move and the lift would hardly lift. Put the proper napa filter on and everything started working again.

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1Litre
Are the belts matched set as intended from Simplicity ? I remember installing them on customers machines years back and it is not fun. I would put a big piece of lumber in front of the tires and run that machine against it. After you cause the slipping for a short time shut the unit down and reach in by the pulley and feel for heat on the belts or pulleys. You will not have to touch them just very near . If they are cool then you can start looking at the hydro unit. You can test the charge pressure by installing a pressure gauge in the proper port .

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bigwheel
I did use a fram filter and I will replace to be safe, I need to check those bushings I was not focused on them upon re assy and I also need to verify belt slippage via heat build up. Thank you all for the great ideas! I will be working it over the next few days Tom R

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arnoldir
Hey Bigwheel, I am the guy who posted the Fram filter saga. Short summary, Orange Fram Filter was starving the hydro pump causing almost no torque. Put on simplicity filter and tractor can spin tires if bucket is placed against tree. Power max has filter on the suction side, and can have no finer than 20 micron filter element on it. Good luck getting your sorted.

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bigwheel
Good news, I replaced the fram filter with the napa1307 and noticed a big difference. Also checked for belt slip and worn bushings and they seem ok. Most importantly I was able to work it loading firewood this weekend, Thank you all, lomg live the tractor club! My next challenge is to get the engine to full power @3600 rpm. I currently cannot get above 2600 rpm. I have adjusted the power needle valve and govenor to no avail. The onan engine starts to hunt at any higher revs. Tom R.

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midnightpumpkin
I was able to reduce the hunting, but not eliminate it completely by rebuilding the carb. New needle and seat and a good cleaning. Interesting that the filter made a big difference. I have read about that before, but you have documented it first hand. I run NAPA Gold filters on all of my tractors with good results. John U

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D-17_Dave
The hunting usually indicates either a lean condition in the venturie of the carb as it transitions from the idle mixture control jet to the main jet. Increasing the idle to the richest setting that it will idle should help this. It may also indicate a sloppy worn govn. linkage. The age of these engines it could be worn linkage so check it closely. If you find wear in the linkage ends try lengthening the linkage rod a round of thread on one end. Another option is to copy the way Briggs handles this wear issue and add a very light spring to the linkage that pulls the wear points together thereby reducing the "float" effect that could exsist.

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bigwheel
With the throttle in full position there is roughly .06 inch total slop overall. Half the slop is in the throttle valve and shaft and the other half at the linkage rod ends. So I will start there. Not sure what I can do with the throttle shaft and carb body. Thanks Tom R.

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1Litre
That is alot . You can ream the bore and rebush with thinwall brass valve guide bushings. The shaft is the problem . I have made new throttle shafts before . Takes a vertical mill and some silver solder to fabricate one.

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