Ask the Mechanic

Penetrating Oil Fix for Hydraulic Cylinders

(Progressive Farmer image by Schlegelfotos / Getty Images)

READER: I have a John Deere 7200 tractor with a 3-point lift problem. It raises great but is slow to go down. It really likes some weight on it before it will drop down so I can hook up implements. I was told that I may have to rebuild the hydraulic cylinders to fix this problem. Got any ideas?

STEVE: You are not alone. Since the lift cylinders on your 7200 are "one-way cylinders," there is no fluid pressure from your tractor used to lower the lift links -- only pressure supplied by the load on the links forces the fluid in the cylinders back to sump. Therefore, they won't fly down like they fly up without a load and can even get stuck so they won't move down at all. Try this: Spray the top of the cylinders with a good penetrating oil, and let it soak a few hours. Work the cylinder up and down. The penetrating oil will usually do the trick. The seal rusts and pushes the rubber seal a little harder against the ram, making it snug. If your links still go down slowly with a load on them, you will need to adjust your rate-of-drop valve. It is adjustable to compensate for the load on the drag links, allowing the links to drop without "cutting the rope" when hooked to a heavy load like a mounted chisel plow or planter.

READER: I have a 4530 Mahindra tractor, and I need to top off my hydraulic system. I blew a hose when folding up my rake and need to add a little oil. However, I can't find where to add oil to the system. The owner's manual does not say anything about it. I called the dealer that sold it to me, and they told me that I could add oil below the clutch pedal where the dipstick is located. Now, I found the dipstick, but the opening is very, very small. They don't make funnels that small. The opening is like the size of a small straw. Is there any other place to add hydraulic oil to this tractor?

STEVE: I have had this question before on Mahindra tractors. Behind the right rear of the seat, you will see a big plug marked "transmission breather." Remove the breather/fitting in the top cover, and you will have plenty of room to stick a funnel in there. The dipstick under the clutch pedal will tell you when the tractor's hydraulic cavity is full.

A Note from Santa Steve


Here we are again: that time of the year when people enjoy exchanging gifts. Once again, I surveyed naughty and nice farmers and ranchers to see what they put on their Christmas lists. Higher grain prices? Cattle prices? Cheaper tractor parts? Nope, nope and no. Here are the top five things we can really use.

P[] D[x] M[x] OOP[F] ADUNIT[] T[]


No. 5 a plush receiver hitch cover to protect our shins (%#&*!!@ ouch)


No. 4 a sharp knife to cut open round hay bales (But not just any knife, a knife with a beeper on it so we can find it after we put it down for just a second. Where is that thing, anyway?)


No. 3 a good cell phone with normal-sized keys that we can use without asking our grandkids how to make it work.


No. 2 a CV joint light enough that we can stick it on
the PTO shaft by ourselves and still come away with all our fingernails, and ...


The No. 1 answer is: trailer wiring that runs the lights, stop lights, turn signals and brakes all at the same time (that's too much even for Santa Steve, my editor tells me).

SAFETY TIP OF THE MONTH:

I have often seen individuals place a metal object between the positive and negative posts to check for voltage in a potentially dead battery. Don't do that. Gas from electrolyte is highly flammable, and a battery can explode. When installing a battery, always connect the ground cable last. "No charge" for this Safety Tip of the Month.

Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email mechanic@progressivefarmer.com.

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