How to flush a hydraulic system with kerosene??

[Warbird]

Any of you guys know how to flush the hydraulic system on a snow plow?  I've got an old Meyer E-47 (I think) that just stopped moving the other day.  Sounded like the pump was cycling fine but the blade would barely move up or side to side.  Started to smell hot hydraulic fluid so stopped trying.  Some local trucking guy told me he's positive I've got water in the system and that I should flush it.

Any secrets on how to do this?  I'm guessing I'll have to completely take off the side rams and hoses, then just swish some kerosene through them.  How do I flush the hoses and the main ram, though?

Also, the directions say that is using kerosene, to flush it out with something else.  What "something else"??  Can I flush the kerosene out with hydraulic fluid, then fill her up with hydraulic fluid again?

Finally, do I have to do anything special to bleed the air out of the system when it is all back together?  And do you guys recommend any special type of fluid for a plow or is standard hydraulic fluid okay?

I appreciate any info or help.

[Gary_C]

Knowing where you live, I would suggest you first warm the entire system up and then drain everything. Check to see if the old hydraulic fluid is cloudy with water mixed in or if there is free water in the bottom of the sump. If you really wanted to, you could then fill with diesel fuel or kero and just cycle the system briefly to see if it works. Don't run it very long as either diesel or kero does not have much lubricating ability. I probably would not flush the system, but just add new fluid (warmed up of course) and see if it ran ok.

As far as the hydraulic fluid to use, I would ask some local supplier what to use. What I would recommend may not work in Alaska. Look for a low or multiple viscosity hydraulic oil. Exxon Univis is one that comes to mind that is used on aircraft hydraulic systems. However an automatic transmission fluid that is normally used for your area may work. For regular hydraulic fluid, an ISO 32 or lower may work.

Stay warm, spring is coming.  8)

[Warbird]

Thanks Gary.  I pulled the plow into the shop before I left for work this morning.  Talked to another friend who said the same thing, that I should just drain it and not worry about flushing it.  I know it works when it is warm, it only has the problem when it is cold.

We're supposed to get another 2" of snow overnight.  Looks like I'll be working on the plow after work tonight. :

[beenthere]

Warbird
Is the oil cloudy?

[Warbird]

Warbird
Is the oil cloudy?

I won't know for sure until I drain it tonight.  2 years ago when I drained it, there was some pretty ugly looking sludge that came out at the very end.  I'm going to check and see if there are filters anywhere on the unit, as well.

[Sprucegum]

I was just going to suggest you may have water in your filter that may be blocking you oil flow when cold. Anew filter and low-temp oil might be all you need.

[Slabs]

I wouldn't put anything in the system but hydraulic fluid.  If you feel the need to flush, do it with hydraulic fluid.  Kerosene and diesel may destroy the seals in the system because they are not compatible with lighter petroleum distillates.  If you do wind up with milky fluid, working it and getting it hot enough to boil off the water might be an option.  Watch the filter carefully.  If it's permeated with fluid OR water the other may not pass through and starve the pump overheating and damaging it.

Good luck

[Warbird]

Well, I drained it and changed out a couple of seals.  Yes, beenthere, the fluid was really cloudy.

It still doesn't work.  It will not lift the plow, although it goes side to side.  When I extend the ram without the plow attached, I can push it back in with just my weight.  :(  Not sure what this means.  I didn't check to see if I could do this before I started.  Either it's just plain broke or I put the ram back together wrong? 

[beenthere]

On my plow the lift ram is just a one way ram. Likely yours is too.  So you should be able to push it back in (although it sounds like yours pushes in real easy like the oil is slipping by the ram, so it may need some internal repair). 
Did you have the one-way ram apart?
Is there a way to check out your lift ram...like possibly change it out with another?

If the two angle rams work ok, then you apparently have a pump that is working.

Hang in there, Gary_C is on the way.  ;D

[Gary_C]

That's not a good sign. I am not familiar with snow plows, but it could be the seal in the cylinder is not in right or the control valve is stuck open. A quick way to check the cylinder would be to plug or cap the ports and see if it still moves under pressure. You could also crack the fitting on the liftcylinder and operate the valve to see if oil leaks out under pressure.

If that test shows no oil pressure, try cracking a fitting before the valve and see if the pump is working.

Hang in there, Gary_C is on the way.  ;D

I guess what beenthere is saying is I know how to make hydraulic systems leak fluid. I'm not sure if that is good or not.  :D

[beenthere]

I strongly suspect you have a one-way ram on the lift of your plow (one hyd line leading to the lower end of the ram). The oil pressure extends the ram, and the weight of the plow pushes it back down.   
(Edit: now I see by reading post #11, where this unit is self contained, and not the one-way ram I was thinking  : )

If so:
Here is a site that has a good line drawing of a one-way ram.
Shows the position of the seal at the top. Did you change that seal?
http://www.hydraulicsupermarket.com/hydraulic-ram.html

Also, when you operated the ram for the first test after repair and new oil, did you hold the control valve (to raise) long enough to push out all the air from the system? 
If the seal is leaking or in wrong, I'd think you'd have hyd oil running out around the seal.

If not, sounds like a plug somewheres, and cracking some fittings between the ram and the pump should pinpoint the problem. Might be messy tho. Good luck.

[isawlogs]

 I am not sure of the Myers plows , but on a western plow , the lift cylinder is internal , no outside hoses , it is part of pump casing.
All you need to do is get a packing and seal kit and put it in . your pump works , your angle cylinders proved this .
I had to blead mine and I did it with the angle cylinder , removed the return line and opened the fill cap and poured hydraulic oil in while letting it flow out into a pail from the return line .
  Unless you have cable control wich I doubt , you may have a cable that is not adjusted correctly .

[Warbird]

Thanks guys.  Isawlogs, yes, the lift ram is part of the casing, no external hoses. 

The 'seal' I replaced was just the seal that goes around the shaft, which keeps water from going back into the unit.  However, to replace that seal, I had to pull the entire top of the cylinder off.  The entire ram assembly came out of the casing when I did this.  It did not "feel right" when I put the ram back into the casing.  Almost like the bottom of the unit did not go into the hole properly at the bottom of the casing.

Yes, I ran the pump for a bit to try and cycle air out.  The pump sounds like it is running fine.  I suspect you guys are right and that fluid just isn't being directed into the lift assembly properly.

beenthere, when the plow/ram has been raised and the switch is in 'neutral' position, the ram should stay extended, holding the plow up in the air.  It does not and will not raise the ram with any real weight on it.  The ram extends fine with no weight on it.

Gary_C, you are prolly right that the seal inside is not in right but I've got no idea how it's supposed to go in or what it even looks like.  I wasn't expecting the entire ram assembly to come out when I popped the top off of the cylinder.  It did this because the shaft seal was lodging on some paint and dirt that was at the top of the shaft.  When the entire assembly came out of the pump body, it made kind of a squishy sucking noise.  I could not get it to make similar noises when putting it back in and again, it just didn't "feel" like it went back in all the way or correctly.  Could this be the problem?  If so, how do you know when the assembly has been reinserted back into the pump body correctly?

I'm hoping I haven't damaged anything...   I'll be calling the Meyers shop when they open today.  I've already spent $83 on this and am praying I don't have to spend more.  :-\ 

Thanks for the info and help, gents.  I really appreciate it.

[Warbird]

Just talked to the Meyers guy.  He says there is an o-ring at the bottom of that assembly that is likely chewed up, broken, missing, or I just didn't get it all put back together right.  He told me to bring it in and he'd charge me $50 to put the thing on his test bench and make it right.  Plus, I'll get to stand there and watch and learn.  Should be money well spent.

I'll let ya know if that's all that was wrong.

[Warbird]

So it turned out to be an o-ring at the bottom of the assembly that popped out when I was trying to get the top plate off the cylinder.  The guy knew his stuff and fixed it all up in short order.  I didn't get to watch but oh well, the plow is working again!

Thanks for all the info and help, guys.  I learned a lot.