Wheelhorse#1 1,446 #1 Posted January 1, 2023 (edited) Hello folks and happy new yr to all ! I have a 1973 12 auto.Its has developed a leak on the hydro pump, seal ? I think? I replaced the seals on the axels a wile back. Problem is I can't find any info on this Sundstrand model. 90-2019.Somewhere along the line someone must of swapped out the original hydro, should be 90-1136 piston to piston .As far as I can tell WH didn't use a 90--2019 on any of their trans. Any help to where I could find info on this pump would be apreciated. The trans seems to work pretty well although reverse has somewhat slowed a bit. Id like to get this leak fixed and look into the reverse problem. Haven't really worked this machine any yet just run around at the show , plan to use it to push snow. Edited January 1, 2023 by Wheelhorse#1 1 Share this post Link to post Share on other sites
pfrederi 17,173 #2 Posted January 1, 2023 Is hydro motor a piston to piston (round housing) or a hydro gear (oval figure 8 looking case). Clean the front of the transaxle then run it around for awhile. If it gets oily most likely candidate is the motion control. I split the tractor to replace the O rings. Some people with thin fingers, dexterity that I don't have it and some luck can do it with out splitting. 2 Share this post Link to post Share on other sites
Wheelhorse#1 1,446 #3 Posted January 2, 2023 (edited) Thanks.I’ll give that a shot. @pfrederi I believe is hydro gear motor I’ll get a pic today. Edited January 2, 2023 by Wheelhorse#1 1 Share this post Link to post Share on other sites
squonk 39,040 #4 Posted January 2, 2023 If it's a an unmolested 73 with ATF it should be a Hydro gear but better check 1 Share this post Link to post Share on other sites
Wheelhorse#1 1,446 #5 Posted January 4, 2023 (edited) After searching for info .It’s definitely a hydro gear.But it been change out for a different model for some reason or another. I didn’t have to run it long before I could see where it was coming from.From the motion control seal, looks like a pain to get to but maybe not impossible. Since any leak in the pump can cause performance problems its probably safe to say it could be the reason for a poor reverse or reverse valve issue ? Edited January 4, 2023 by Wheelhorse#1 1 Share this post Link to post Share on other sites
pfrederi 17,173 #6 Posted January 4, 2023 I doubt the leak is causing the power loss in reverse more likely a problem with the plastic slider not moving the control far enough.. or the reverse acceleration valve. I have the two o rings you will need PM me you address I will mail them to you. Share this post Link to post Share on other sites
Wheelhorse#1 1,446 #7 Posted January 4, 2023 36 minutes ago, pfrederi said: I doubt the leak is causing the power loss in reverse more likely a problem with the plastic slider not moving the control far enough.. or the reverse acceleration valve. I have the two o rings you will need PM me you address I will mail them to you. Thank you Sir..will do. I replaced the plastic slider a wile back and still had the same issue even after adjustment.When I do the seal ill look at that reverse acceleration valve too.Thanks for everyones help and suggestions.Big help as always ! 1 Share this post Link to post Share on other sites
Wheelhorse#1 1,446 #8 Posted January 4, 2023 Update to anyone who may be interested. I pulled the reverse valve and found a bent spring.The valve has what looks like scoring but when in ran my finger nail over it it feels smooth. I couldn't retrieve it with my magnet so I sacrificed a cheap pair of angled needle nose pliers,it was jammed in there a bit. Im thinking 🤔 wheel horse parts and more Carries these springs. Of course I didn’t have the correct size in my stash. 1 Share this post Link to post Share on other sites
953 nut 52,027 #9 Posted January 5, 2023 17 hours ago, Wheelhorse#1 said: Im thinking 🤔 wheel horse parts and more Carries these springs. Yes he does. https://wheelhorsepartsandmore.com/product/transmission-acceleration-springs-2-7052-9215-2-7264-9858/ 2 Share this post Link to post Share on other sites
Wheelhorse#1 1,446 #10 Posted January 5, 2023 Just purchased a set ..thx Share this post Link to post Share on other sites
Wheelhorse#1 1,446 #11 Posted January 7, 2023 (edited) In preparation to replace the worn n leaking O-ring on the motion control shaft I managed to snap my last T30 Torx bit. Everything was going fine until ..Snap !! These are the two Torx screws for mounting the housing to the hydro pump. I think I may have to try some heat next go round and perhaps a better quality bit. Or perhaps there is a better way ? Edited January 7, 2023 by Wheelhorse#1 Share this post Link to post Share on other sites
pfrederi 17,173 #12 Posted January 8, 2023 Interesting. My Sunnies are older (Charger/ Electros) at that time they were using 12 pt bolts. Since you are going to be replacing the O rings I guess a little heat won't hurt anything. 1 Share this post Link to post Share on other sites
Wheelhorse#1 1,446 #13 Posted January 8, 2023 (edited) @pfrederi I received the rings yesterday in the mail.Thanks again. They definitely need to be replaced. I looked on the part’s diagram and I’m not even seeing the bolts listed for the mounting bolt for the cam support block. Picked up another Torx bit today from TS. Removed the cam block and quickly discovered where most of the fluid was coming from. Looks like I have to hunt down a support block,I’ll post on the wanted ad.part #5993 Cam Block support. All in all not too difficult a job ,but definitely not sausage fingers friendly 😁👎 Edited January 8, 2023 by Wheelhorse#1 Share this post Link to post Share on other sites
pfrederi 17,173 #14 Posted January 8, 2023 (edited) Screw is a socket head 1/4" by 1/2" #911037 Check with A to Z Block is part# 5993 I have fat clumsy fingers i have to take the hydro off the tractor you did great!!! Edited January 8, 2023 by pfrederi 1 Share this post Link to post Share on other sites
