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Simon C

Senior Member
Joined
Jul 1, 2015
Messages
664
Location
Rocky Mountain House , AB., Canada
Occupation
Heavy Equipment Mechanic
Just wanted to say that 22 years ago I worked for a mining company in Northern Ontario that had a lot of Hydraulic Drills that after a few years every single hammer body developed cracks that would only leak when the drill was in percussion mode. With way too much testing we always found out that, with even sleeved bores the leaks would come back. It was a simple fix. New housing, valves and pistons and all was good. We had figured it out with dye on a test bench. The leaking oil had the dye in it.
We even had air drills that leaked between ports from the percussion hammering also.
It would not surprise me at all that a housing could crack. Maybe the unit worked on a hammer before you owned it or was made weak in one location at the factory.
The possibility is always there.
Simon C
 

Jason Klassen

Well-Known Member
Joined
May 29, 2021
Messages
95
Location
Enderby, British Columbia, Canada
The new Dp sensors from Deere sub to a non-adjustable sensor.
If that's the case then it looks like someone replaced it at some point with a genuine part. I like that!

Maybe the unit worked on a hammer before you owned it or was made weak in one location at the factory

Very interesting Simon, before I went through all this I would never have thought that a big lump of cast iron could have these issues. I knew that lots of heating and cooling could affect cast iron, like trying to weld it with the wrong technique.

It makes sense that vibrations and shock loading from a hammer drill would do some damage, however I am leaning towards the factory defect theory. When that one wrecker told me that they were "known" to crack that got my attention. When a guy who sells parts for a living knows about a problem, it must be fairly common.

Did a little test today. I checked the pump pressure with controls in neutral.

Spec in the book is 440 - 580 psi (P mode)

Old control valve:
Idle 260 psi
P mode 270 psi falling to 240 psi

New control valve:
Some strange things happened, I might have to re-test, something might be up with my gauge. After un hooking the gauge the needle remained at 380 psi. I am pretty sure it normally falls back to zero.
Idle (cold) 280-300 psi
Idle (20deg C oil temp) 360-380 psi
P mode 390 psi (stable)

I know these numbers are lower than the book spec but in other parts of the manual I found this...

284 psi 2.jpg

The engine does idle better with the new control valve so the dp sensor must be getting the correct differential pressure to signal the pump to run at minimum output. With the old control valve the differential pressure would have been lower causing the computer to think that there was load on the system. It would then signal the pump to put out more flow which put an unexpected load on the engine while it was idling causing the engine to run rough.
 

Simon C

Senior Member
Joined
Jul 1, 2015
Messages
664
Location
Rocky Mountain House , AB., Canada
Occupation
Heavy Equipment Mechanic
I hope you get it all figured out. Sometimes there is no way around new parts. I use to live in West Kelowna but am back in Alberta.
All the best to you in your repair.
Simon C
 

Jason Klassen

Well-Known Member
Joined
May 29, 2021
Messages
95
Location
Enderby, British Columbia, Canada
Thanks Simon! You're so close yet so far away haha.

Ok, I don't know how I would be able to measure the pressure at the pump and get the spec the book was calling for? According to the picture from the manual that I posted above, the unloading valve opens to control the system pressure in neutral to 284 psi.

The initial readings with the gauge were 280-300 psi, so I am going to call that good and say that the unloading valve is working properly in this control valve.

Now the gauge is a little wacky. 360 psi seems to be it's new zero point. I put the gauge back on the machine this evening and it read 640 psi. 640-360 is 280 psi so it seems to still be working but with a new zero point.

I saw some people on YouTube talking about "venting" or "burping" a gauge. Basically pressure can build up inside fluid filled gauges from temperature or altitude changes causing the needle to move. If the little rubber cap on the top is cracked open a hair the needle should fall back to zero.

I tried that and nothing changed, still stuck a 360 psi. Any ideas? I am going to have to look into this a little more.

WP_20221212_001.jpg WP_20221212_005.jpg
 

Simon C

Senior Member
Joined
Jul 1, 2015
Messages
664
Location
Rocky Mountain House , AB., Canada
Occupation
Heavy Equipment Mechanic
Caterpillar sells gauges that are pretty good. Even $50 for a gauge may sound like a lot but minimal as compared to a whole day wasted over a faulty gauge. I have quick connects on my gauges and 2 of each. Change gauge and if still same then move on with diagnosis. I don't like working a day for $50.00
Simon C
 

Jason Klassen

Well-Known Member
Joined
May 29, 2021
Messages
95
Location
Enderby, British Columbia, Canada
I am looking for a new gauge right now. The problem is that when I bought my testing kit the gauges in it came with a weird thread on them. You can see it in the first gauge pic. It called G1/4B, its a british pipe thread and it turns out that everything sold in north america is NPT. I didn't know this or else I would have got a different kit.

The gauge that is broken I got from a seller on ebay in Australia because they seem to use that thread and I wanted a gauge that would work with the hoses and adapters in the kit.

I have contacted the Wika gauges location in Edmonton because their site shows that they sell a adapter to go from 1/4 npt to g1/4b. Then I could get any npt gauge and run it with the other pieces in my kit.

I will look into the CAT gauges.
 

Jason Klassen

Well-Known Member
Joined
May 29, 2021
Messages
95
Location
Enderby, British Columbia, Canada
Ok, got my new gauge and put it to the test. It's a zero to 1000 psi gauge so I can use it for all the lower pressures like pilot pressure and the system base pressure that I have been trying to measure. I got the 4 inch dial gauge because I thought it would be easier to accurately tell what the reading are.

I am posting a video link so you guys can see a little better. The needle dips once in a while but it corresponds directly to the pulses I could feel in the pilot line. The pulses are from the pump angle control solenoids. I know that when the oil is warmer the solenoids fire a lot more often so the needle would probably stabilize.

When the needle is not dipping it seems to show 280-290 psi and the book spec is 283 psi.

Seems like this new control valve is OK. I have moved the machine around and the tracks have not randomly stalled on me either.

I think the last issue now is that the proportional solenoids are not compensating properly so combined operation is not great. As you guys saw earlier I rebuilt the proportional solenoid block so I need to go back and check that the pilot pressure and pilot reduced pressure are correct. Then put a lamp harness in and see if the computer is actually firing the solenoids and possibly adjust them.

WP_20221230_001.jpg

 

Jason Klassen

Well-Known Member
Joined
May 29, 2021
Messages
95
Location
Enderby, British Columbia, Canada
Great detailed reports and follow-up. A lot is way beyond me but some folks will be able to work with your write-up.

Thanks Gary, I have received quite a built of help from the forum members and I hope all this info can be helpful to somebody else.

Small update:

Since the the base system pressure seems to be good now that the new main control valve is installed, I wanted to test the upper end and see if the system relief pressure is correct.

It does not matter which function I choose to test the system relief pressure with, the main relief valve will always open at it's set pressure. If I wanted to test the individual circuit relief valves I would have to temporarily raise the system relief valve pressure setting above the circuit relief valve setting to observe it. The circuit relief settings are 200-400 psi higher than the main relief on this machine.

To test the main relief the hydraulic oil temp is supposed to be 50C +or- 5C. I was only able to get the oil to 20C. It was about -10C ambient temp when I did the test and I did not want to work the machine a bunch to get the oil temp up.

The throttle should be in "P" mode (full throttle) and then I held the bucket in the dump position for a few seconds over relief and recorded what the gauge said.

I got 4800 psi. The specs in the manual are a little funny:

350 (+20 -0) kg/cm2 or 4978 (+284 -0) psi then below this in the same row and column is says
370-300 kg/cm2 or 5262-4270 psi

Later when the weather is nicer I will do more testing but for now it looks like buying and installing the new to me used main control valve was worth it.

I also installed some leds to replace to burnt out factory sealed beam lights, they are crazy bright!
IMG_0028.JPG IMG_0031.JPG IMG_0033.JPG IMG_0035.JPG
 

Gary Layton

Well-Known Member
Joined
Mar 9, 2021
Messages
190
Location
Georgia
Love the lights!! I put an LED light bar on the cab of my CAT 320CL and 2 LED "pod" lights on the back...they are wonderful.
 

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Jason Klassen

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Joined
May 29, 2021
Messages
95
Location
Enderby, British Columbia, Canada
Well, looks like we are not exactly out of the woods yet! In the previous post I mentioned getting 4800 psi, but that was with 20C hydraulic oil temp.

Today it was 25C ambient and I was able to get the oil up to 50C like the manual wants without any trouble. Then I ran the machine up to full throttle (P mode) and stuck a pipe in the drive sprockets to test the tracks over relief. 4200-4400psi was the result.

I held the bucket over relief in both the dump and curl positions and got the same thing, 4200-4400 psi.

Next I gave the main relief valve a quarter turn clockwise, expecting a pressure increase but got the same 4200-4400 psi.

Then turned it a quarter turn counter clockwise expecting a decrease in pressure but still got the same 4200-4400 psi.

The spec that I mentioned above (5262-4270 psi) I figured out is the upper and lower limits of the working pressure.

Looks like I am hovering around the lower limit... but I am confused as to why I didn't get any change with the main relief valve adjustments???
 

Jason Klassen

Well-Known Member
Joined
May 29, 2021
Messages
95
Location
Enderby, British Columbia, Canada
Hey mg2361, I'm happy your still checking up on me!

My old control valve with the internal cracks was from a ex100-3, it had the plug on top and a surge relief that acted as the system relief on the bottom.

The "new" control valve is correct for my machine, it being an ex120-2. There is a "System Pressure Regulator" on top (this is the one I was trying to adjust) and a "Surge Relief" on the bottom.

1-System pressure regulator.jpg2-Surge relief.jpg
 

Jason Klassen

Well-Known Member
Joined
May 29, 2021
Messages
95
Location
Enderby, British Columbia, Canada
Ok, I first gave the surge relief a 1/4 turn and then 1 full turn in. Both made no difference, still 4200-4400 psi.

I started with a 1/4 turn because after doing the conversion 28.5 kgf/cm2 is equal to 405 psi.

The system pressure regulator on top feels like it is at the end or just about the end of it's adjustment range, bottomed out. Seems to me someone was trying to adjust the pressure when this control valve was in a previous machine and just kept on turning until they got to the end.

I was hoping to adjust the surge relief to where it needed to be today and then back off the system pressure regulator to just below it.

I didn't want to keep turning adjustment screws for no reason so I just left the surge relief at 1 full turn in from where it was.

The functions that I used to test the pressure today were boom up, stick out, bucket dump and bucket curl.
 

LACHAU

Senior Member
Joined
Aug 11, 2009
Messages
976
Location
Saigon, Vietnam
Please note that the system pressure regulator valve is integrated into the Unloading valve.

EX120-2 Neutral Circuit.png
EX100-3 Neutral Circuit.png
 
Last edited:

Jason Klassen

Well-Known Member
Joined
May 29, 2021
Messages
95
Location
Enderby, British Columbia, Canada
Thanks Lachau, I understand that system pressure regulator sits on top of the unloading valve and that they work together to control the system pressure.

I am unsure of what you would like me to check, or what I might not be understanding?

This is the procedure I have been using to check the system pressure.
1-4.7.jpg2-4.7.jpg
 
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