MF 135 with independent PTO Grinding while disengaging?

bugman53 · Mar 29, 2020

mllud said:
Wouldn't the return port have to be left open as an intake. Is there another intake?
It doesn't seem they would just loop the same fluid. It has to have an intake to get the fluid into the short cycle your referring to.
I would search for a flow diagram. May not exist .
I would drill and tap the same size as the internal pump fittings. I know that using a larger return line than the feed( intake) can cause cavitation.

From what i can tell there is a screen and pickup in the bottom for the IPTO and AUX pump but the return from the side cover goes straight into the back of the pump on that same pickup circuit. So i guess it will pick up any additional fluid it needs from the pickup but the return of hot oil would keep circulating in the loop with the exception of any internal leakage of the Multi power and IPTO back to the case. Does not seem to be a problem for a external cylinder but if running anything continuous i don't like it. The only reason i could see for them doing that would be to keep from contaminating the fluid in the tractor if something external had a different fluid. I am sure the engineers had a good reason at the time i just don't know what it is.

I think i am going to cap the return to the pump and just plumb the return from the side cover into the case so it will circulate all the fluid through the system. I also love the idea of adding an external filter. Then it would filter all the oil in the system ever couple mins.

mllud · Mar 29, 2020

I use this company for hydraulic fittings hoses, fittings. As always shipping costs can kill the good price.
Most hydraulic filter heads come with a pressure bypass that allows oil to bypass if the filter is dirty. Some also have a pressure switch that gives a warning that the filter needs changed. I like those. That switch can be wired to a light on the dash. You may already know this.
Its good that you found the problem with the grinding. And your adding additional service while its opened up.
You can find a single tap with the right sized drill for that tap sold together. That cast iron usually taps nice. It gets a little tight as you go in farther with the tapered threads.
I don't have any connection to the company in the link.

Surplus Center

bugman53 · Mar 29, 2020

mllud said:
I use this company for hydraulic fittings hoses, fittings. As always shipping costs can kill the good price.
Most hydraulic filter heads come with a pressure bypass that allows oil to bypass if the filter is dirty. Some also have a pressure switch that gives a warning that the filter needs changed. I like those. That switch can be wired to a light on the dash. You may already know this.
Its good that you found the problem with the grinding. And your adding additional service while its opened up.
You can find a single tap with the right sized drill for that tap sold together. That cast iron usually taps nice. It gets a little tight as you go in farther with the tapered threads.
I don't have any connection to the company in the link.

Surplus Center

Thanks man! I will do. The more i think of it i think instead of plugin the return for the pump i am just going to add another pickup tube with a screen to the bottom of the case to make sure it gets plenty of low restriction flow to the inlet and then run the return back to the case. That will give it 2 pickups to make sure it can supply the required about of oil. Then take your advice and pump up the external ports to a filter. If i ever want to add rear remotes it would be simple to add an open center spool valve. I am thinking an hydraulic top link would be a nice addition for scrape blade work.

I had no ideal there were filter housings with electric switches. That is pretty cool i will check into it.

bugman53 · Apr 20, 2020

She is back together and working. The replacement pump was a 21 spline mark 2 and my tractor was a 10 spline. I had to swap the pump shaft and modify the gear that couples the pump to the transmission shaft as the earlier gear was not machined for the 2 plate style mount. So i machined the gear on the lathe and made new bushing to fit the steel plates. All the hydraulic lines had to be made as they were in different locations. I put stainless steel flex sections in both IPTO and AUX hydraulic output lines to allow everything to move and not stress the hard lines.

The AUX pump , i drilled and tapped the side cover like the original and temporary made a loop pipe until i add a filter and rear remotes at a later date.

I rebuilt the IPTO clutch pack, The original friction disk were steel with a friction material like brake lining, The new ones are a bronze metal type material.

I put new seals and bearings in everything i had apart. And she works great!

The PTO engages MUCH harder than before. Almost to firm. Before it would bring my 6 foot finish mower up to speed smoothly now it engages quickly. my guess is this is due to now having the proper pressure available. I did notice a touch of chatter in the PTO as it is engaging just like wet brake chatter but only if i engaged it at higher rpm it would chatter for a split second before it fully engaged. Maybe the new bronze disk need to seat?

The multi power now kicks in firmer than before. I did not check the pressure before but with 2 cracked lines i am sure it was low. Also i did not realize what it was but before if i would start in a high gear with multi power in high it would buck a little like the clutch was slipping now it takes off smooth in multi power high.The multi power clutch was probably slipping due to low pressure and bucking.

I also got the draft control working and she seems good to go!