135 Hydraulic Pump Rebuild

Here's the main problem: the part numbers for my valve chambers are 888 702 M2 and 888 702 M3 respectively, which equates to the .944 diameter pistons. I can't seem to locate this diameter valve chamber as a replacement. Will a rebuild kit with a different diameter valve chamber work? Should I get a rebuilt pump and just replace the original unit entirely? The camshaft and other parts appear to be in very good condition, but it will need new O-rings, etc. to bring things back up to speed.

Thanks in advance for your help. Tim

A rebuild is definitely a practical option, and not difficult at all. The key is removing any burrs in the valve holes so you don't cut the o-rings on the spring retaining plugs when you insert them. It only takes a hairline mark on the o-ring to cause them to fail.

First - are you sure of your .944 measurement? I've done a number of them, and have only seen .91 and .98 pistons. My Vapormatic parts book shows your valve chamber numbers take .98 pistons.

(This doesn't mean I have seen them all! Nearly every week somebody on the site here tells me something new about these critters. I've got a dozen of them, started my first overhauls in 1976, have been through them all now, but still learning. I thank my lucky stars for folks like Big Dean, John(UK) and David P!)

There are two valve chambers shown in my 165 book (same pump as the 135). The difference is the top plug and retaining ring. One has a flat topped plug , conventional square section snap rings to hold in the plugs, and square grooves in the valve chamber for the ring.

The other valve chamber has chamfered shoulders on the top of the plug, a wire retaining ring, and a round bottomed retaining groove.

The parts book is not clear which is the later configuration, but I think it's the wire retaining rings.

Either type fits the side plates and pistons, as long as the plugs and snap rings match the chambers. I mixed them once, (square section snap rings on chamfered plugs in the round bottom grooves), and two of the rings fractured and blew out.

I tried refacing seats, and valve chamber ball valve replacement kits. Neither was satisfactory. The last valve chambers (new, aftermarket) cost me only $50 each - by far the best way to go.

So 2 new valve chambers, a valve kit and an o-ring kit, maybe new pistons and rings, and you will be back in business - a lot cheaper than a complete pump.

You have expanded my knowledge base - the wire rings are the later chambers!

I'm not sure whether the .91 chambers will work or not.

I'd stick with the larger .98 ones myself, because you know they will fit from the part numbers, (the smaller bore chambers may not interchange mechanically due to different mounting bolt or port hole locations, and you can't tell this until you have them side by side) and because of the 10% greater output volume from the larger piston displacement.

The cost should be the same.
Good luck!

I had same problems recently filter was destroyed
and filter particles and trash were sucked by the pump and caused damages to pump components.

I decided to bring the pump to a MF dealer to have it rebuilded. They refaced the valve seats with a special tool put rebuilt kit. R&R Labour cost $145.00 any way I had to buy the parts.

I reinstalled the pump and "voilą" operates like a champ.

Just my little pump story.

Good luck

Joe Ferguson

Our nearest MF dealer employees are friendly and always willing to help and assist. They even help
if they have a used part at good price if the new part is too long to obtain in order to return our equipement to work as soon as possible. One of my friends had a dealer few miles of his farm...he was impressed by the service and courtesy of our dealer he lives 60 miles away and transfered his bussiness to our dealer.

Good service is investment for future bussiness !

Good luck with your dealer

Joe Ferguson