Help with 8n hydraulics please

[Jon Decker]

I have been using my 52" 8n for backblade snow plowing. The other day, after lowering the backblade, the lift arms just stopped working out of nowhere. Prior to this, the hydraulics have been strong (I used a 3-pint bale spear and moved over 300 round bales this last summer) and never exhibited any knocking under load.

I have checked the obvious - fluid level, PTO is spinning, etc.

I have removed the right inspection cover. There is plenty of hydraulic fluid (it was actually overfilled and I drained it to the lower inspection plate bolt hole). The fluid is a little dirty, but other than that it looked ok.

With the engine running, and the touch control lever to the full up position, there is no fluid raining from the top, so the piston above appears to be fine. I can see a little turbulance in the fluid in the rear area (swirling up from behind the differential), and the fluid "glopping" up and down towards the front with the pto engaged and the engine running. I"m not sure what is normal to look for here...

The Touch control linkage moves both up/down and front/back when the touch control lever is moved up and down. Again, I don"t know what is normal to look for here either. The rod looks slightly bent to the rear, but I"m guessing thats normal.

If it would be of any help, and can get some video of what it looks like in the inspection cover while the engine is running and the PTO engaged.

Any help is appreciated!

 

[Jon Decker]

Forgot to mention - there is one other "test" I did..

I removed the hydraulic test port plug with the engine off. (Not much more than 1/4 cup of oil came out).

I then turned the starter over with the key off, PTO engaged, trans. in neutral so that the starter would essentially turn the PTO pump. When I did this with the test port plug removed, not much of any oil came out, almost as if the pump wasn't pumping anything. I don't have a pressure guage to do a pressure test, so I figured this would be the next best thing

 

[CJ in Michigan]

Cracked valve chamber?

 

[Jon Decker]

Well, today must be my lucky day...
I grabbed my camcorder so that I could video inside the inspection cover. When I started it up, the lift went right up and is working just fine again.

Must have been dirt plugging up some intake holes possibly? I guess the best thing to do right now would be to change the fluid and hope things hold up until spring when I have the time and energy to tear things down properly, clean everything and inspect.
Thanks!

 

[jackinok]

crack drain plug open slowly and make sure you have no water to run out.

 

[ZANE]

I believe you may have had a stuck control valve. Possibly from ice?????

Zane

 

[lha]

Concerning the test port,You can remove the plug,and turn the pto counterclockwise and it will force oil out of the port.I did this to see if there was water in my pump.No water came out,but I found out the oil was clean,at least in the pump.---lha