3020 PS transmission pressure?

gf in S.IL · Mar 17, 2018

I have a 1965 3020 diesel with the power shift transmission. I changed the hydraulic fluid for the first time since I bought the tractor. Replaced both filters and checked the sump screen (was clean). Refilled the transmission with fresh Hygard. Started the tractor and all seemed fine. (and all may be) The transmission gauge went up to the high end of "normal" which where it normally stayed prior to changing the fluid. Ran the tractor for the first time where the engine was at PTO speed. Transmission pressure gauge went all the way to the high side. Gauge's needle comes down to the normal range when the engine rpm is lowered. Gauge's needle drops a little when you push the foot and inch pedal as it always has done. I'm not a mechanic and not sure what I may have missed doing.

buickanddeere · Mar 17, 2018

Install a known accurate test gauge that reads in psi. The filters may have been partly plugged and possibly masking another problem.

DONMYEIL · Mar 17, 2018

That is a lube gauge,checking oil pressure after everything has lube pressure . Pressure drops as oil warms up is normal .

Kent Petersen · Mar 17, 2018

That,s BS Buick what he is saying is normal

buickanddeere · Mar 17, 2018

(quoted from post at 10:46:37 03/17/18) That,s BS Buick what he is saying is normal

Overall pressure is now higher . Why is the pressure now higher both cold and hot ? Just what exactly is the actual pressure instead of trusting a LMH dash gauge that has had 50+ years of fluctuations and vibrations .

gf in S.IL · Mar 17, 2018

I think I need to clarify. Before changing the fluid and filters, when I was using the tractor at anywhere near PTO rpm the pressure gauge needle would top out at the high area of "normal" when cold. As has been pointed out, the pressure would go down a little as the system warmed up. Now, the needle goes on past the normal range when the engine is above 2000 rpm. The fluid I drained out was clean looking ( not milky ) and there were no particles of any sort on the filters or the sump screen. The filters I pulled out were John Deere. Don't know about the old fluid, but would guess was Hygard. Everything may just be fine, but this is my "main" tractor and I sure don't want to do anything to jeopardize the hydraulic or power shift systems.

SVcummins · Mar 17, 2018

What does the guage do when you have an implement attached to the hydraulic outlet and raise the implement?

gf in S.IL · Mar 17, 2018

I did not have the tractor hooked up to anything with a hydraulic cylinder since changing the fluid and filters. From what I am seeing in the replies, I think I need to do some checking to get some details of pressure and also to see if/how operating a hydraulic cylinder affects the gauge's reading.
I really appreciate this site.

SVcummins · Mar 17, 2018

I am asking because my gauge when I raise an implement or raise the 3 point after the oil is warm so I was wondering if yours did the same thing?

SVcummins · Mar 17, 2018

This is where mine reads with no demands on the hydraulic system . trans temp gauge at the milddle of the normal range

gf in S.IL · Mar 17, 2018

Thanks for posting the picture. That is where my gauge is going now. What had me concerned was it never used to go that far to the right before.
I'll hook a cylinder up to the tractor on Monday and let you know what happens.

SVcummins · Mar 18, 2018

Thanks

fdt860 · Mar 19, 2018

You should not be concerned at all. The 4020 PS I drove had it where you could not even see the needle when above 2000 RPM.
Your only way to really measure pressure is to put up a gauge from an Industrial machine. (see 770 picture below)

SVcummins · Mar 20, 2018

So tell the dealer I need a trans psi guage from what model?

buickanddeere · Mar 21, 2018

(quoted from post at 21:48:38 03/20/18) So tell the dealer I need a trans psi guage from what model?

Could go to the JD dealer with the actual part number after you look it up in the free parts book on the JD web site .

fdt860 · Mar 21, 2018

The one pictured is a mechanical gauge from a 770 grader.
It is connected to the clutch test port.you can probably use the Deere fitting as well.
AT37479 around 185 for the gauge but a direct bolt on without sender to buy. This should not replace the lube pressure.

Another option is a Stewart Warner mechanical gauge 284R.
Cost one third and should be as good quality. But the facing would not be green.

770 graders have bunch of Deere gauges that would look nice on a 4020 PS if the dash allowed for it. Engi e oil pressure is cheap aftermarket if electric from a 450 crawler.

3020 PS transmission pressure?

gf in S.IL

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