Cleaning M936A1 Hydraulic Fluid Filter

One of my tasks for this weekend is draining my wrecker's hydraulic fluid, servicing the filter, putting it back together and refilling the fluid. I'm reusing the old fluid, but I'm pumping it through a spin-on hydraulic fluid filter on the way back in, then adding more to top it up. I'll probably need to get more fluid; it was already 5 gallons low, I expect to lose some fluid in the process, and my local industrial supply place just had one bucket of ISO 46 / SAE 10 fluid on hand.

Here are some pictures of the work in progress. The filter appears to have a reusable wire mesh screen that I should be able to clean up and reinstall.

Harbor Freight sells some handy items, like the magnetic paper towel holder and magnetic disposable glove box holder shown here.

I'll take some pictures of my drum pump setup when I refill the fluid.

There's a drain plug hiding on the bottom of the hydraulic fluid tank that I was hoping to remove in order to get out some of the scum that I assume is on the bottom of the tank, but it didn't want to come out even with a 1/2" drive air impact wrench.

By draining the tank before removing the filter, not too much fluid came out.

Good idea on the towel holder.

Do you have a filter gasket or going to use sealer or...?

I don't have any new gaskets. I'm planning to use RTV, just as it was apparently sealed when I took it off. I bought a tube of RTV at Pep Boys that's supposed to be especially good for gear oil that I'll try using for both the filter and a leaking axle flange seal.

It's amazing how fast those nitrile gloves fill up with sweat on a hot day like this!

I think I'll try dropping the filter screen into my heated ultrasonic cleaner with a solution of Purple Power in it, if nobody tells me that sounds like a bad idea first.

Ultrasonic sounds like a great idea. Can't think it could be a problem.

I was dripping sweat out of my rubber gloves the other day and wondered why I never had that problem when I was younger? Do old guys sweat more?

I like the paper towel and glove holders. With the M936's you need a lot of paper towels and gloves for sure!!!!LOL

Did the filter show that it was dirty?

Yes, the indicator said that it needed cleaning. Now that I can see the filter, it's certainly covered with crud!

I was just kidding about the gloves. I work on my trucks naked so I don't get my clothes dirty, then I just hose myself off with some farm diesel when I'm done. The red 164 dye keeps my cheeks nice and rosy.

nf6x said:

I was just kidding about the gloves. I work on my trucks naked so I don't get my clothes dirty, then I just hose myself off with some farm diesel when I'm done. The red 164 dye keeps my cheeks nice and rosy.

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MY Eyes!!!

Ok, fluid is back in the truck now. Here's my pump setup. I bought the pneumatic drum pump many years ago to do this job on my M543A2, but never got around to doing it. I finally got the rest of the hardware to make the drum pump usable. I put a spin-on hydraulic filter on the pump outlet. The pumping slowed down a lot by the time I was done, so I figure that filter is full of crud that it took out of my fluid. I may cut the filter open later to see how much crud is in there.

The fluid hose is made for fuel pumping, and the fittings at each end are electrically connected for static control. So, everything from the pump to the nozzle is electrically connected. I figure I'll use the setup for fuel pumping at some point. When I pump anything more volatile than oil, I'll also bond the whole thing to the earth and the vehicle.

The air valve is made to vent the outlet side to the atmosphere when it's closed, so all pressure is removed from the pump system immediately when I close the valve. I ran the pump off air from the wrecker's rear emergency glad hand. I'd probably use a different air source if I was pumping something volatile like fuel, so I wouldn't need to have the engine running.

Maybe I should add pressure gauges on the filter head to show when it's clogged?

Creative! Will it pump beer?? Mmm.. beer

If I ever develop a taste for oily beer, then I have just the pump for it!

Haha yeah

Anyhoo, I made this thread because I hadn't seen pictures of the inside of a wrecker's hydraulic filter before, so I thought I should share some now that I got inside of one. I wish I had enough hands to take some pictures showing how the shutoff valve works.

Were did you get that air powered pump? I like that.

I found it on eBay. I don't remember what I paid for it. You should be able to get a good one from McMaster-Carr, or a cheap one from Harbor Freight.

I expected the spin-on filter element to be cruddy, but it doesn't look too dirty at all. I probably could have kept using it. Well, it's trashed now. The tool with the filter head in it is a filter opener. It's a purpose-made tool for cutting open spin-on filters to examine them for metal shavings and so forth. I think I got it from Aircraft Spruce. It works a lot like a tubing cutter.