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Playin' In The Dirt Again
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Discussion Starter · #1 ·
Hello Forum.

Back in late February I bought a John Deer 750. This unit was made for John Deer by Yanmar in Osaka, Japan in about 1984, as best as I can tell.

It is working splendidly. Last week I decided to do some routine maintenance, about 50 running hours before the records say that it should be done. I noticed something unusual and I want you experts here to comment about it.

From the beginning in February I noticed that there was a whining sound whenever I activated the hydraulic lift for TPH attachments. I also noticed that whenever I lifted a plow or tiller, it seemed to jerk a bit, not doing the lifting as smoothly as I was going with the lift lever alongside the seat.

After changing the transmission/hydraulic fluid and cleaning the associated metal screen filter, I notice that there is now no whining whatsoever. I also notice that the jerking is gone. The hydraulic operation is smooth and quiet. I am thinking that the fluid I drained out was somewhat thicker than what I put back into the tractor's gearbox. What came out had a brownish color, but it did not appear to be overly dirty, and nowhere near opaque.

The stuff I put in came from Walmart in two 8 quart blue plastic jugs...Tech something. I made sure that it matched or exceeded the John Deere specification for hydraulic/transmission tractor fluid in my manual.

What do you think about the cause of, and going away of, the sound and jerkiness in my 750 hydraulic system?

:Tractor2:
 

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I'm not a mechanic by any stretch, but it sounds like you needed a hydraulic fluid/filter change. :)
 

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Playin' In The Dirt Again
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194 Posts
Discussion Starter · #3 ·
I'm not a mechanic by any stretch, but it sounds like you needed a hydraulic fluid/filter change. :)
Hello JDFanatic.

Thanks for your reply.

I am inclined to think that it was in order too. The tractor I have does not have a proper hydraulic fluid filter... at least not one of the oil style spin on types. It uses a stainless steel screen filter of sorts. When I took that out, I cleaned it in a pan of mineral spirits using a paint brush at first, and then blowing out the screen with compressed air. I found within the mineral spirits wash a lot of fine metallic material settled at the bottom. That may have impeded the throughput of the screen "filter," and especially so with thicker oil.

Why it is that the oil I took out was thicker than what I put in is a puzzle to me. I am left wondering if the previous owner may have just poured in some other oil product when it got low. Something like ordinary transmission fluid or even motor oil. Anyway, I am confident that the stuff in there now meets or exceeds spec JD20-B. It is JD20-C, and the system is working.

I can see that the valve cover gasket has no obvious breaks in the paint. This makes me wonder when the last valve adjustment was. I think I will tackle that one next, before cold weather settles in.

:Tractor2:
 
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