John deere 302a backhoe

[Tomtom81]

I've been having problems with my backhoe not moving and losing all hydraulics. I've done split it apart 3 times. I have replaced the front reverser clutch and engine clutch and all filters plus cleaned the screen then it worked just a little then quit. I just split it apart again and removed the transmission and everything looks fine visually. The transmission pump gears looks good. How would you tell if the trans pump is bad it just looks like big oil pump. The only thing that I can think of is that the seals are leaking internal.Any help would be greatly appreciated. Thanks so much

 

[Tx Jim]

Did you check to determine that reverser linkage is shifting valve completely between fwd & reverse? Have you checked hyd pressure on control valve?

 

[Tomtom81]

I didn't check the pressure. I bought some
gauges to check it with but the fittings
were wrong so I said the hell with it. The
reverser lever was shifting fine. When the
tractor was cold it would move some and
the lift and bucket would work. But once
it warmed up a little it all would stop
working. You could pour hydraulic fluid in
the reservoir by the radiator and the
lifts would start working for a min then
quit again. So that tells me that
something is stopping up or not pumping.

 

[Tx Jim]

To correctly repair closed center hyd problems similar to what your 302A displays requires VERY good,comprehensive diagnostics. Guessing & replacement of parts normally will not solve the hyd problem!

The reason I asked you about checking reverser linkage is the linkage has a history of a failed pin allowing slack in linkage so control valve won't control hyd pressures as designed.

Have you checked to be sure hyd filter relief valve is seating properly & not stuck open?

Have you isolated power steering valve to be sure it's not leaking internally?

Have you checked to determine priority valve isn't blocking hyd flow/pressure to rear of tractor?

 

[Determined]

(quoted from post at 05:05:07 04/06/20)
To correctly repair closed center hyd problems similar to what your 302A displays requires VERY good,comprehensive diagnostics. Guessing & replacement of parts normally will not solve the hyd problem!

The reason I asked you about checking reverser linkage is the linkage has a history of a failed pin allowing slack in linkage so control valve won't control hyd pressures as designed.

Have you checked to be sure hyd filter relief valve is seating properly & not stuck open?

Have you isolated power steering valve to be sure it's not leaking internally?

Have you checked to determine priority valve isn't blocking hyd flow/pressure to rear of tractor?

Excellent advise TX Jim has given you, I have a JD 401 that is basically the same and in the 25 years I have owned it I have encountered almost every problem Jim listed.

Going by memory the fitting to attach a gauge to the port on the reverser I had to modify a brass reduction bushing.

 

[Tx Jim]

Fitting to attach gauge to reverser housing should be 0.562 IN ORB.

 

[Tomtom81]

I have checked the the pin and all was
right. As far as the filter relief valve I
have check and it was stuck but clean it
up and got it working fine. But the others
I know nothing about. Doesn't the
transmission pump supply oil to the main
hydraulic pump? I just know it will work
just for a min when first started up and
then everything quits working within 5
min.

 

[Tx Jim]

Trans pump lubricates trans/diff,supplies oil to reverser then supplies oil to front hyd pump.

I suggest to cap supply line to power steering valve then check operation of hyd's.

 

[Tomtom81]

Could leaking seals inside of the
transmission cause these problems. Also
where are the other two valves your
talking about. When I first got this thing
it would go in reverse but that's it. I
tore it apart and replaced the front
reverser clutch assembly it was burnt up
bad and the bushing that the front clutch
housings runs in. Then it worked good for
about 2 hours then everything started
quitting.

 

[Jim.ME]

(quoted from post at 14:31:27 04/06/20) Could leaking seals inside of the
transmission cause these problems. Also
where are the other two valves your
talking about. When I first got this thing
it would go in reverse but that's it. I
tore it apart and replaced the front
reverser clutch assembly it was burnt up
bad and the bushing that the front clutch
housings runs in. Then it worked good for
about 2 hours then everything started
quitting.

You replaced the clutch with a used one, they told you was good, right? Did you check it, reseal it, or just put it in as you got it?

 

[Tomtom81]

I did not reseal it but the clutches all
looked good. But that shouldn't cause the
lose of lift or hoe not to work. Should it

 

[Jim.ME]

Anything in the transmission, with oil being supplied by the transmission pump, that uses more oil than designed, leaks, or stops a designed flow; could stop oil from getting to the front pump. When you dump oil in the reservoir and it works says to me the oil is not getting there. It can be as simple as the hydraulic filter being plugged, even if it looks good. I have seen it happen, hydraulics work, quit, let it set awhile, and had hydraulics back for a bit. Brake discs were metal to metal plugging the filter with grindings, but it looked good until I cut the filter open. This may not be your problem, but the point is looks do not always tell the story.

You say you have split it three times. Did you check all the internal tubes for cracks and proper seating. Did you replace all the O-rings on them and the seals, washers and packing used to drain the ports in the cases?

We posted in the past about pressure checks, I see now that didn't happen. As TxJim posted, you need to do the diagnostics. He has given you some good things to check on.

 

[Tx Jim]

Ditto what Jim.ME stated. You need to perform some very extensive diagnostics to solve CC hyd problems.

 

[Tomtom81]

I never pulled the transmission till now.
It's been just the front reverser clutch
and engine clutch. I've replaced the
filters twice and still same. But since
its apart now I'm going to clean
everything good and replace all the seals.
Then put it back together so I can check
the hydraulic pressure. I do have a parts
and service manual for the machine. It
should show the valves that was mentioned
earlier. THANKS FOR ALL THE HELP

 

[Tomtom81]

Also just asking I've seen other backhoes
where the lift and bucket digs but wont
move. So there could be multiple problems
right? But what your saying is that if
anything internal in the transmission is
leaking then it wont supply the main
hydraulic pump?

 

[Tx Jim]

Any significant internal hyd leak be it the low or high pressure circuit can alter correct hyd operation

 

[Jim.ME]

Also just asking I've seen other backhoes
where the lift and bucket digs but wont
move.

The short answer is, not all are designed and built the same. JDs of the design you have, need the charge oil from the transmission pump feeding the main hydraulic pump; problems in either system can affect the other. Thus diagnosing problems is often more in depth since the systems are interdependent. Case, and many others, were designed such that the driveline and hydraulics were completely separate systems. In those the machines the transmission/shuttle/reverser can fail and the hydraulics will still work, or the hydraulics can quit and it will still move. HTH