Question on Hydraulics for 530CK w/ Model 32 Backhoe

First off, sorry for the long post, but I figure when it comes to problem solving….the more information the better.

Well, after giving up on this project for about a year, I am just now getting back around to trying to solve the issue my 530CK has with a lack of power to the Backhoe.

I have a later model 530ck which has the 2 spool loader valve and the backhoe valve block which does not possess an adjustable pressure relief valve (i.e. main pressure relief valve in the loader control valve is for both the front loader and backhoe).

The back pressure tests were conducted per the service manual with the following results:

Front Loader (bucket @ full travel) - 2,200 psi
Backhoe (stabs & bucket @ full travel) - 1,400 psi

I have replaced the beyond power o-rings, checked all my connections, and verified fluid levels.....but for some reason I am still getting low power to the BH.

Not sure what to do at this point.....from my layman’s understanding of how this loader control valve works, it would appear that pump pressure is applied first to the loader spools, then (if neither spool is actuated) fluid then goes to the beyond power plug, which directs it to the BH control valve which (due to its open flow design) sends it back to the sump as long as no spools are actuated.

I currently have the pressure gauge installed in the test port on the side of the loader control valve, but was wondering if there was any benefit to installing it in-line between the beyond power plug and the BH control valve. If my understanding of this hydraulic circuit is correct, then theoretically, I shouldn’t see any pressure differences from that of the test port. However, if I were to dead-end the hydraulic circuit prior to the BH control valve, then I should see the actual line pressure supplied to the BH control valve (without any pressure loss due to the BH control valve).

I guess my thought process is that it the BH supply line pressure is the same as the loader (~2,200 psi), then I know that the problem is in the backhoe control valve; however if the line pressure is still ~1400, then the issue has to be in the loader valve. Does any of this sound logical?

Also would dead ending the BH supply line (for a very short period) cause catastrophic failure to the system, or present a dangerous situation? Is there a better way to determine where my problem is?

Again, thanks for reading all of this, and I appreciate any advice you guys can give me.


Thanks,
Rich

I haven't consulted the Case backhoe manual lately, but I know that hoe has its own circuit relief valves. Problem a hoe system-relief valve also. Have you checked them? My Case 33 hoe on my 580CK has a several relief valves on the backhoe valve-bank and one is adjustable.

The 580CK has one main pump that runs through the open-center of the loader valve, on through the open-center of the backhoe valve, and back to sump.

When using the loader, all pressure oil goes directly to the loader valve.

When using the backhoe, all pressure oil has to pass through the loader valve first before it arrives at the hoe-valve. When you use a hoe-function, you close off oil-flow and pressure rises. When you then lose pressure, it can be bleeding off in either the loader valve, OR a circuit/system relief valve in the backhoe valve-pack.

I've never seen a hoe on any full size open-center machine that did not have its own relief valves. But, I don't own a 32 hoe, just a 33 and a 33S, all made for 580CKs.

The proper way to isolate the loss of pressure would be to have a flowmeter diagnosis done on the system. A flow meter T'd into the pump supply and back to sump if used in an educated manner would allow you to check leakage on every single circuit on the machine in one hookup. Although as JD said there are many seperate relief valves it was customary for Case to use the loader valve relief for the backhoe main relief also. there were very few exceptions to this except for some very early 580's and 680's. If you had not replaced the power beyond rings I would have advised you to do so as I have done many of these out in the field. If you have any doubt you may want to revisit that area. All secondary pressures are above main except boom down so should not affect the main readings when systems are against relief. Boom down is much lower for safety concerns and can be read at low idle. mEl

(quoted from post at 03:29:48 05/04/10) The proper way to isolate the loss of pressure would be to have a flowmeter diagnosis done on the system. A flow meter T'd into the pump supply and back to sump if used in an educated manner would allow you to check leakage on every single circuit on the machine in one hookup. Although as JD said there are many seperate relief valves it was customary for Case to use the loader valve relief for the backhoe main relief also. there were very few exceptions to this except for some very early 580's and 680's. If you had not replaced the power beyond rings I would have advised you to do so as I have done many of these out in the field. If you have any doubt you may want to revisit that area. All secondary pressures are above main except boom down so should not affect the main readings when systems are against relief. Boom down is much lower for safety concerns and can be read at low idle. mEl

Click to expand...

Thank you both for responding.

The reason I do not think I have a seperate BH pressure relief valve is because I did not see one on the parts diagram that matches my valve assembly (see below)



The previous model did have an adjustable pressure relief valve on the input side, however mine only has a check valve on the inlet side. I have checked the poppet, o-rings and the spring associated with it and could find no errors.

I have considered the individual relief vales as an issue, but I do not yet have a manual pump to specifically test each one for proper settings. Additionally, all circuits of the BH seem to have reduced power (i.e. stabs won't lift back wheels, boom will barely lift itself without a load, etc.); this makes me believe it is more of a systematic issue.

I agree a flow meter test would be ideal, but I when I contacted my local Case dealer to see if they had one for rental/ sale...they acted like they never heard of a hydrosleuth. I did find one on-line but the guy was asking $250; which made it cost prohibitive. I guess I could make one, but would need to research that a lot more to figure out what components I need.

When I changed the beyond power plug orings last year I conducted pressure tests which are consistent with this years test results. I pulled it over the weekend again, but the orings seemed to be in good condition.

I am prepared to pull the BH control valve, but I am fearful that I may break something in the process which may not have been broke in the first place. According to the Case parts guy, only the o-rings are availble through Case; he said I should treat each metal part (e.g. poppets, valves, springs, etc.) like it was gold. I would like to identify the BH control valve as the problem before taking any chances.

Without the use of a flow meter, would there be anyway to check the line pressure to the BH (preferably without the control valve in line)?

Would dead-ending it be dangerous? or would it not tell me anything?

Again thanks so much.....your help may me prevent me from parting this thing out

Rich

Thank you for your input, I included my response to your post within the latest post from mEL; but wanted to thank you personnally.

Rich

(quoted from post at 20:43:02 05/03/10)
Thank you for your input, I included my response to your post within the latest post from mEL; but wanted to thank you personnally.

Rich

Click to expand...

The secondaries only come into play on the hose that goes to that port as they are in circuit between the spool and the cylinder and one valve protects one side of any particular function so looking at them as a cause of widespread low pressure is fruitless. A bad secondary would affect only one side of a particular function. If you were to disconnect the supply line from the loader valve power beyond to the hoe valve at the quick disconnect you would be obviously deadheading the flow. The pressure created will most times keep the engine from starting. This can be overcome by useing one of the loader functions while cranking the engine. If the power beyond circuit is good then the pressure should be 2200 once the loader function is returned to center. This would be no different than holding a hoe functon on demand as the oil flow would be stopped and main relief would take over. If the pressure is indeed 2200 doing this then the problem is obviously hoe valve related. A quick question!! is the pressure the same across all the circiuits on the hoe?? I have seen many older hoes that have enough accumulated wear in the spool handles and linkage that the levers are stopping in the back or front of the lever slots and not stroking the spool fully. I have lengthened the slots on many to restore full spool travel and brought weak units back to full power. Post back. mEl

mEL,

I have checked spool travel, as I have seen you recommend that before. The control levers do not contact the frame when fully actuated, and the frame has not yet been modified to lengthen the travel (possibly indicating degrading spool). So, it appears (at least for now) that I am getting full spool travel on all cylinders.

Regarding pressures I only performed the pressure test (using the port on the loader valve) on the BH bucket and both stabilizers; the reason for which is the crowd, boom, and swing cylinders all have specialized relief valves, which may affect my readings. However, in the absence of quantifiable pressure readings on each BH cylinder, I would say that each cylinder shows about the same level of performance given its specific function (i.e. everything works, but not as well as it should). It might be worth noting here, that the front loader work perfectly and with lots of power; also I do not see and creep in the front loader cylinders when using the backhoe (possibly indicating a failing spool in the loader control valve, when under back pressure from the BH).

I will try to dead-end the BH supply line using the method you described and report back; I know it’s not the best test, but it is something I can do quickly without obtaining additional tools.

I will keep on the lookout for another Hydrosleuth, but would be curious if you have any advice for building a flow meter myself. I can guess at the basic design (flow meter, Tee, Hand Valve, etc), but wasn't sure if I need pressure and temperature indicators also.

I really appreciate your advice.

Rich

(quoted from post at 07:39:13 05/04/10)
mEL,

I have checked spool travel, as I have seen you recommend that before. The control levers do not contact the frame when fully actuated, and the frame has not yet been modified to lengthen the travel (possibly indicating degrading spool). So, it appears (at least for now) that I am getting full spool travel on all cylinders.

Regarding pressures I only performed the pressure test (using the port on the loader valve) on the BH bucket and both stabilizers; the reason for which is the crowd, boom, and swing cylinders all have specialized relief valves, which may affect my readings. However, in the absence of quantifiable pressure readings on each BH cylinder, I would say that each cylinder shows about the same level of performance given its specific function (i.e. everything works, but not as well as it should). It might be worth noting here, that the front loader work perfectly and with lots of power; also I do not see and creep in the front loader cylinders when using the backhoe (possibly indicating a failing spool in the loader control valve, when under back pressure from the BH).

I will try to dead-end the BH supply line using the method you described and report back; I know it’s not the best test, but it is something I can do quickly without obtaining additional tools.

I will keep on the lookout for another Hydrosleuth, but would be curious if you have any advice for building a flow meter myself. I can guess at the basic design (flow meter, Tee, Hand Valve, etc), but wasn't sure if I need pressure and temperature indicators also.

I really appreciate your advice.

Rich

Click to expand...

you could manufacture a device to load the circuit but without a device to measure actual GPM I can't see an advantage. our flo meter will allow us to see 1/2 GPM difference between circuits, that's picking out a pretty small leak. Get back after you deadhead it, only use enough rpm to keep it rumnning. mEl

Sorry for the delayed response, had to address a few other problems (i.e. bad points) before I could do the dead end pressure test.

The result was >2000 psi after dead-ending the BH supply line after the beyond power plug. This leads me to believe the problem is definately in the BH.

The BH service manual I have only describes the operation and maintenence of the previous BH control valve used on the model 32 (i.e. the one with the adjustable pressure relief valve). So, I have been studying the parts diagram for my valve and doing my best to understand the similiarities between them. As I mentioned it does not appear that my valve has a dedicated main relief vavle (much less one that is adjustable), however I am curious about the spring loaded spool on the outlet side of the control valve; does anyone know what this does?



Thanks Again,
Rich

What you have circled is the regeneration valve and spool assembly. The regeneration check valve is at the other end of the control valve assembly.
The models that don't have a main relief in the BH section have the main relief incorporated in the loader valve.

What is the problem with your unit? Sure is a lot of BS recommendations to wade through. If it's low pressure to the BH and loader is fine, take the pressure relief valve section out of the loader valve and clean the small passages and/or bronze screen in the poppet. Had the same thing happen when the previous owner decided he didn't need an element in the return line filter.

As has been stated before, the loader relief valve controls both the loader and hoe pressures so if the loader valve is showing the proper pressure and the hoe pressure is down there is a problem in the power beyond or in the hoe control valve, the loader main relief controls both and cannot act differently for one or the other. As Magnet has stated, I have seen the screen in the relief poppet needing cleaned and the main relief needle and seat worn to the point of being erratic, but that affects all circuits downstream. I have been working on these units anchoring the service department professionally since 1962 full time at a franchised Case dealership where we sold dozens per year for many years. I have had the advantage of having been Case factory trained at Racine on most hoes since 62 when I started. I don't put BS up here, only the information gleaned from years of on the job experiences. Acting on the info given that this unit has no high pressure relief within the hoe valve if it can be determined that the problem is beyond the power beyond sleeve then since the regeneration spool has been checked in the LH end cap it may be wise to make sure the check valve in the RH end cap is seated properly as that is a dividing point between high pressure and low pressure as regen oil can join pump flow at that point to reduce cavitation , and if not seated for some reason the high pressure oil could escape to low pressue as the valve should be on its seat unless return oil is needed when the boom is dropped in a ditch quickly and the flow required to keep the cylinder full exceeds the gpm available from the pump. this stops the "lag" as the oil would have to come from the pump to fill the void created by the piston moving faster than the pump can supply, a common complaint before the valves incorporated regen circuits. This advice is given as best I can without the information gleaned by a flowmeter test which would isolate the problem area. While I respect everyones viewpoints who reads and answers posts here, I can only post those things that I know from years of experiences to be true on hundreds of machines and read and seperate good from bad advice and often gain info that gives me a fresh perspective, something that occours quite often on here as there are others with sharp minds and a similar background as mine who contribute.

First off, I would like to thank everyone who has given input; I have been battling this thing for quite sometime and have been coming up short.

Specifically, I thank mEL for his insight, I had similar questions regarding the main relief valve, but was too afraid to ask on the assumption that it would further show my ignorance.

However, to Old Magnets point, I did remove and check the main relief valve last summer at the same time I replaced the O-rings on the beyond power plug. With that said I will pull both of them again and check their conditions.

As an update I have pulled the RH (as seated in the tractor) regeneration plug and removed the spool. The O-rings on the cap looked in good condition (but will be replaced anyway) and the spring was not broken or distorted; the action on it is very tight and I am unable to compress it using my hands alone.

One thing I did notice on the spool was a slight difference in surface appearance on the upper land. The lower portion of the upper land was shiny and smooth, however the upper portion of the same land had a lower sheen. The best way I can explain it is, that it almost looked like it was "blued", similar to what you would see on a cylinder or valve which was experiencing blow by. I realize it is most likely not due to overheating, but there is a definite difference in the patina within the upper and lower portions of the upper land. (I can try and post a pic if anyone would like to see) Is this normal, or could this be a potential root cause of the problem?

I am also looking to replace the supply and return hoses to the BH. This is largely due to their condition (the outside casing is shedding) and also to remove the quick disconnects (since the BH unit will rarely ever be taken off).

I am also looking to get a flow meter to test the unit, in order to help isolate the problem. If anyone has any ideas where I could buy/ rent one near St. Louis, MO; I would be greatly appreciative.

Thanks again to all that have helped so far!

Rich

Please do not over look the valve assembly in the opposite endcap as I believe that if it is not seated properly pressurized oil could escape to the low pressure side of the valve. Without going over the manual I believe that this is also part of the regen circuit, mEl.

I pulled that plug first, but did not see any issues with the poppet assembly. The spring was not broken or distorted, and appearred to have enough strength to seat the poppet against the upper portion of the valve body.

The O-rings on the plug also did not seem to be worn or damaged, but I have ordered replacements for it also. (it seems the only parts I can get for this valve body are O-rings).

Is there anything else I should be looking for on these check valves/ plugs?

Did you ever get this resolved? Wondering, my backhoe is exhibiting the same issues, low power to the hoe.