# JD 410 Backhoe slow hydraulics



## kenp

Hi, I am new to this forum. We have a John Deere 410 Backhoe, s/n 342132T. The hydraulics for the backhoe suddenly got very slow and weak. The loader stopped working at all.
The first thing I did was check the output pressure of the pump. It was only about 800 PSI.
Next thing I did was to try adjusting the output pressure with the adjusting screw on the port on the bottom of the destroke control valve on the hydraulic pump. Turning this screw either way made no difference in the output pressure (still about 800 PSI).
Next, I checked the main hydraulic filter. It looked clean with no signs of any obstructions.
Then I pulled out the cylindrical pre-filter screen that is about 1.5 inches in diameter and 8 to 10 inches long that is inside the main fluid reservoir where a short rubber hose connects the reservoir to the main hydraulic filter assembly. The screen was not damaged and it was clean. I reassembled it.
The next thing I did was the unscrew the cap on the 2nd port on the destroke control valve that is next to the pressure adjustment port. My manual shows a screen inside this port that I wanted to check. When I removed the cap there was a significant amount of metallic shavings in the cap and in the port. Obviously the pump is bad but what I don't know is how to determine whether the metal shavings came from inside the pump or somewhere else in the hydraulic system and whether they have spread into other parts of the system.
When I was checking the pre-filter screen in reservoir there were none of these metal shavings in the screen and there were none in the main hydraulic fluid filter when I inspected it. I removed the cap on the pressure adjusting port on the pump and removed the innards from this port. It was clean with no metal shavings. I know the pump was replace about 17 years ago.
How do I determine where the metal shavings originated from? And what should I do to insure that when I install a new pump, it does not get damaged?
The uploaded file is a photo of the metal shavings along with the cap for the port they were in. This is approximate 1/3 to 1/2 the amount of shavings that were in the port and as you can see it looks like there is damage to the inside of the port cap. As I mentioned above I found no trace of these shavings in any of the other places mentioned except this port.


----------



## jd110

The metal filings do look bad. I am assuming you found no screen in that port where the filings came from? The plug looks too small. Later hydraulic pumps omitted that screen for some reason. The oil is filtered before it gets to the pump, so if your filter is good and sealing ok on both sides, it is a pretty safe bet that filings came from the pump. How far the filings traveled in the system after it left the pump is anybody's guess. Before you pull the pump, I would test the transmission pump circuits to be sure there is enough oil being supplied to the main pump. Low supply of oil to the pump could have contributed to it's failure. Prior to the hydraulics quitting, were they working normally or were they jerky? If jerky, that is a sign of low oil flow and cavitation. If transmission pump flow is good, then I would remove the pressure control valve(priority valve) to see if any of the metal shavings are trapped there. Then flush out the line between the pump and pressure control valve before installing new pump.


----------



## kenp

Thank you. This reply is very helpful. There were no signs of any problems at all when the loader stopped working and the backhoe got weak (no jerking or anything else). It was like flipping a switch, now they work, now they don't. There was no screen in the port on the pump where the shavings were. My parts manual shows a screen but the pump was replaced 17 years ago. It was probably a newer pump than in the manual. I pulled both the hydraulic and transmission oil filters and there were no metal shavings or any other foreign materials in either filter. I completely drained the transmission into clean buckets and the oil was clean with no shavings or any other debris. Then I pulled the transmission cover off and fished around inside with an extendable tool pickup magnet. There were no metal shavings or filings or magnet grit at all anywhere in the transmission. Then I flushed out the transmission with diesel while I still had both the hydraulic and the transmission oil filters off and both transmission drain ports open. Again, I used clean buckets for the flush with no signs of anything foreign in the buckets. I did this same flush with diesel on the hydraulic oil cooler into clean buckets. What came out was clean with no debris. Unfortunately, I have already removed the pump without testing the transmission pump circuits. My gut feeling is that the pump is getting oil, because when I could not lift the loader I had to do something because the backhoe was in a place where we could not leave it and it would have been very difficult to get to it with service equipment. When I saw that the pump was only producing 800 PSI I removed the control spring in the pressure control (Steering Priority) valve. This allowed me to slowly raise the loader and get the machine back to a place where it could be worked on. Even though it was slow, it was consistent and smooth when raising the loader. At this point, with what I have done, do think it is safe to just install a new pump or should check anything else first?


----------



## kenp

jd110 said:


> The metal filings do look bad. I am assuming you found no screen in that port where the filings came from? The plug looks too small. Later hydraulic pumps omitted that screen for some reason. The oil is filtered before it gets to the pump, so if your filter is good and sealing ok on both sides, it is a pretty safe bet that filings came from the pump. How far the filings traveled in the system after it left the pump is anybody's guess. Before you pull the pump, I would test the transmission pump circuits to be sure there is enough oil being supplied to the main pump. Low supply of oil to the pump could have contributed to it's failure. Prior to the hydraulics quitting, were they working normally or were they jerky? If jerky, that is a sign of low oil flow and cavitation. If transmission pump flow is good, then I would remove the pressure control valve(priority valve) to see if any of the metal shavings are trapped there. Then flush out the line between the pump and pressure control valve before installing new pump.


I am new to this forum and just realized I need to respond directly to you, so this is the same as the post I added to the thread earlier.

Thank you. This reply is very helpful. There were no signs of any problems at all when the loader stopped working and the backhoe got weak (no jerking or anything else). It was like flipping a switch, now they work, now they don't.

There was no screen in the port on the pump where the shavings were. My parts manual shows a screen but the pump was replaced 17 years ago. It was probably a newer pump than in the manual.

I pulled both the hydraulic and transmission oil filters and there were no metal shavings or any other foreign materials in either filter. I completely drained the transmission into clean buckets and the oil was clean with no shavings or any other debris. Then I pulled the transmission cover off and fished around inside with an extendable tool pickup magnet. There were no metal shavings or filings or magnet grit at all anywhere in the transmission. Then I flushed out the transmission with diesel while I still had both the hydraulic and the transmission oil filters off and both transmission drain ports open. Again, I used clean buckets for the flush with no signs of anything foreign in the buckets. I did this same flush with diesel on the hydraulic oil cooler into clean buckets. What came out was clean with no debris.

Unfortunately, I have already removed the pump without testing the transmission pump circuits. My gut feeling is that the pump is getting oil, because when I could not lift the loader I had to do something because the backhoe was in a place where we could not leave it and it would have been very difficult to get to it with service equipment. When I saw that the pump was only producing 800 PSI I removed the control spring in the pressure control (Steering Priority) valve. This allowed me to slowly raise the loader and get the machine back to a place where it could be worked on. Even though it was slow, it was consistent and smooth when raising the loader.

At this point, with what I have done, do think it is safe to just install a new pump or should check anything else first?


----------



## jd110

If it were me doing it, I would want to disassemble the pump to see what exactly is wrong with it. It is possible it could be rebuilt cheaper than new, but aftermarket rebuilt unit is probably the cheapest. Before installation, I would fill transmission back up with oil, leave the filter cap off of filter, and then start engine briefly, (about 15 seconds)or crank over without starting with a bucket under the filter opening. See how much oil transmission pump supplies in 15 seconds. Should see about a gallon. That should be enough to be sure there is enough being supplied to the new pump. When installing new pump, fill the pump housing with oil in the top hole before putting the fitting in to provide lubrication until trans pump gets oil to it.


----------



## dozer966

You have good advice from jd110 but I'm curious have you cut open the old filters and see what is in the elements.


----------



## FredM

at a guess I would say that the filings you have collected in the screen would be the hard facing from the gears in the pump, you must dismantle the pump and inspect the internals.


----------



## kenp

Thanks to JD110, dozer966, FredM,
I am working on your suggestions and will post results when I get them


----------



## kenp

jd110 said:


> If it were me doing it, I would want to disassemble the pump to see what exactly is wrong with it. It is possible it could be rebuilt cheaper than new, but aftermarket rebuilt unit is probably the cheapest. Before installation, I would fill transmission back up with oil, leave the filter cap off of filter, and then start engine briefly, (about 15 seconds)or crank over without starting with a bucket under the filter opening. See how much oil transmission pump supplies in 15 seconds. Should see about a gallon. That should be enough to be sure there is enough being supplied to the new pump. When installing new pump, fill the pump housing with oil in the top hole before putting the fitting in to provide lubrication until trans pump gets oil to it.


----------



## kenp

Thanks for the help. I took the pump apart and found the source of the metal shavings. The pump shaft has a cone and cup bearing on either end. The cam lobe for the pistons is in between the 2 cone bearings. The lobe has a cylindrical race that rides on needle bearing to actuate the pistons. There is a thrust wash between each end of the lobe race and the cone bearings. The thrust washer furthest from the spines on the shaft was severely damaged. There was a small thin amount of the washer left and the rest is what the shavings came from. Two of the pistons where very tight in their cylinders so I will not attempt a repair and just get a new pump. The photo shows what is left of the thrust washer.









I disassembled the pressure control valve too (steering prioritizing valve) and could not find any metal shavings or debris.

I cut open the hydraulic and transmission fluid filters that where in the machine when the hydraulics failed as suggested by another forum member. They had both been replaced as routine maintenance about 8 months ago. The insides of both filters where very clean.

I did what you suggested and filled the hydraulic fluid reservoir and ran the machine with the hydraulic filter and cap off and collected the fluid that came out in a bucket. I got almost exactly one gallon as you said it should be when I ran it 15 seconds.

As I described in previous posts on this thread, I have checked many parts of the hydraulic system, but not everything, and have not found any debris or metal shavings anywhere except inside the pump. Specifically I have not checked the loader/backhoe working cylinders, the steering system, the brakes, or the reverser. I think I have checked just about everything else. Do you think it is safe to install a new pump without any further searching for metal shavings and debris in the hydraulic system?


----------



## kenp

jd110 said:


> If it were me doing it, I would want to disassemble the pump to see what exactly is wrong with it. It is possible it could be rebuilt cheaper than new, but aftermarket rebuilt unit is probably the cheapest. Before installation, I would fill transmission back up with oil, leave the filter cap off of filter, and then start engine briefly, (about 15 seconds)or crank over without starting with a bucket under the filter opening. See how much oil transmission pump supplies in 15 seconds. Should see about a gallon. That should be enough to be sure there is enough being supplied to the new pump. When installing new pump, fill the pump housing with oil in the top hole before putting the fitting in to provide lubrication until trans pump gets oil to it.


I meant to reply to you and instead I created a new post, so this is also included in the thread as a separate post. The photo is in the separate post and I will not upload it here too.

Thanks for the help. I took the pump apart and found the source of the metal shavings. The pump shaft has a cone and cup bearing on either end. The cam lobe for the pistons is in between the 2 cone bearings. The lobe has a cylindrical race that rides on needle bearing to actuate the pistons. There is a thrust wash between each end of the lobe race and the cone bearings. The thrust washer furthest from the spines on the shaft was severely damaged. There was a small thin amount of the washer left and the rest is what the shavings came from. Two of the pistons where very tight in their cylinders so I will not attempt a repair and just get a new pump. The photo shows what is left of the thrust washer.

I disassembled the pressure control valve too (steering prioritizing valve) and could not find any metal shavings or debris.

I cut open the hydraulic and transmission fluid filters that where in the machine when the hydraulics failed as suggested by another forum member. They had both been replaced as routine maintenance about 8 months ago. The insides of both filters where very clean.

I did what you suggested and filled the hydraulic fluid reservoir and ran the machine with the hydraulic filter and cap off and collected the fluid that came out in a bucket. I got almost exactly one gallon as you said it should be when I ran it 15 seconds.

As I described in previous posts on this thread, I have checked many parts of the hydraulic system, but not everything, and have not found any debris or metal shavings anywhere except inside the pump. Specifically I have not checked the loader/backhoe working cylinders, the steering system, the brakes, or the reverser. I think I have checked just about everything else. Do you think it is safe to install a new pump without any further searching for metal shavings and debris in the hydraulic system?


----------



## jackson101

I'm having a similar problem with my old 410. The loader is weak and the supply hose is "jumpy". Loader raises in in "surges", not smooth. Backhoe dipper, main boom and all others, work great and have enough power to lift the tractor. Did you find a solution to this trouble? Pump was all it needed? After some testing with gauges here are my results; my standby pressure is 2300-2400 PSI, @ 1250 RPM, when the oil is cool. As the oil heats up, it begins to drop off, sometimes as low as 1700 PSI.
When oil is cool, loader works smooth and strong, but,..15-20 minutes later, lots of chatter and slow movement from the loader. I have changed all the filters (with the exception of the mesh strainer), I have pulled and inspected the PCV (priority valve) and found everything in order. Pulled the aperture out and shim out, with magnet, they looked fine, shim is .030".


----------



## jackson101

jackson101 said:


> I'm having a similar problem with my old 410. The loader is weak and the supply hose is "jumpy". Loader raises in in "surges", not smooth. Backhoe dipper, main boom and all others, work great and have enough power to lift the tractor. Did you find a solution to this trouble? Pump was all it needed? After some testing with gauges here are my results; my standby pressure is 2300-2400 PSI, @ 1250 RPM, when the oil is cool. As the oil heats up, it begins to drop off, sometimes as low as 1700 PSI.
> When oil is cool, loader works smooth and strong, but,..15-20 minutes later, lots of chatter and slow movement from the loader. I have changed all the filters (with the exception of the mesh strainer), I have pulled and inspected the PCV (priority valve) and found everything in order. Pulled the aperture out and shim out, with magnet, they looked fine, shim is .030".


Could this "chatter" be cavitzation? Crappy contaminated oil?


----------

