Stupid NF hydraulic lift...
 

I'm about ready to tear this thing out and throw it on ebay I've had so many problems with it. I swear I've had the pump apart three times now. I've got the problems mostly worked out, and to its credit it works great, but I can't get it to stop leaking around the input shaft. The shaft itself is a brand new hunk of 1/2" steel rod from Mcmaster. I have two seals installed. Any chance I put them in backwards?

Tear it all apart again and take photos!!

We like photos!!:biggrin2:

If you just used cold rolled, not machined rod, the rod could be inaccurate enough to cause leaking past a seal (or two!!):bigthink:

That is possible, there is also the chance that the seals got torn upon install or the shaft you got is to small. I know the one on my 123 has a small leak( never done anything to it) I just keep am eye on the oil if it's not making a huge mess. How bad is yours leaking?

It is machined rod, but there is a little bit of slop in the hole the shaft goes through due to wear. I thought about boring it out and pressing in a bronze bushing, not sure if that would help though.

I know the seals are good. I was very careful when I installed them. I'll rip the pump apart (AGAIN!) and take some pics tonight.

It's leaking pretty bad. There's a nice puddle on the bracket under the pump after about an hour of mowing.

Check your valve as well, it can leak out of it and look like it's coming out of your shaft.

A machined rod is not going to be smooth enough not to tear up the seals. If it was turned on a lathe, the surface is like a very fine pitch screw thread. What you need is chrome-plated rod meant for hydraulic cylinders. McMaster-Carr carries metric sizes specifically for that application, but the inch stuff they have may or may not work for a hydraulic cylinder. I can't tell from reading the description.

Matt G. you are right about the pitch on the shaft. All seal surfaces on spinning shafts are plunge ground as not to put a lead in the surface. I machine shafts for a high end gear boxes and lead in the seal surface will cause a seal to leak bad! It will actually pull the oil out of the seal. If its ground stock from Mcmaster then it was ran threw a centerless grinder which means it was ran threw as a spiral and you can probably see it if you hold it in the light just right. Our ruff stock comes in like that and sometimes you can actualy feel the grooves left in the grinding process.

Great info guys! This is the rod I ordered is 1346K17 on the mcmaster site - sorry, I can't get it to direct link to it.

Says the surface finish is 4-8 rms. Not sure what that really means but is sure looks pretty dang smooth to me.

I'll pull this thing apart in a few hours and post back tomorrow...

The problem with that is it is unfinished, and therefore is going to rust and tear up the seals. These are chrome plated for a reason, so 7936K331 would be a better choice. It appears to meet the specs required for hydraulic cylinder rod chrome plating after a quick google search.

Sorry, Matt, I disagree.

Is the shaft on your Cub Cadet engine plated? There is a seal there!

The shaft on your mower deck has seals, it is not plated.

You can not show an example of a pump with a plated shaft, unless it was improperly designed. None of the major manufacturers plate pump shafts.

A pulley or a coupling will not stay on a chrome plated surface.

Maybe you were thinking the OP was talking about a cylinder.