Cat 424D hydraulic & transmition issues

[mrminds]

hie all
i have an older model backhoe loader
cat 424 D with RXA serial

my transmission has a 10 second delay before shifting to forward position and a 5 second delay shifting to reverse and this happens with all the gears
also the machine does not accelerate beyond 15 km/h when on the road also struggles going uphill
the shifting delay started 20 hours after replacing transmission filter and transmission oil.. ( strainer also cleaned) both the filter and oil have been replaced twice thinking the 1st once where faulty..
the F N R selector has also been replaced

issue no2

having endless issues with hydraulic pump.. repaired twice but pump will only work for few days then looses pressure.. when stripping the pump, valve plate and pistons always gone..
each time pump comes back from repairs new oil & filter used but issue continues.. i was told i could be having a bypass on the valve banks or my oil cooler is not cooling the oil or i have a dirty hydraulic system or the hydraulic pump pressure compensator is not set correctly machine or either faulty

the front bucket lift and tilts ok when pump is operational but the backhoe functions tend to be slow especially the bucket when its halfway closing it becomes fast then opens fast till halfway and becomes slow, the swing and lift functions work fine, the hydraulic cylinders have had new seals installed

 

[ahart]

Have you cut your hydraulic filter open to see if there are any debris in there? Have you put any gauges on the hydraulic system to check pressures? I’d be checking low pressure standby pressure as this provides lubrication while the pump is in standby. Also need to check the tank to make sure nothing is blocking the suction hose.

 

[mrminds]

Hie
I did cut the hydraulic filter no debris or shavings
I don't know if I'm reading my gauge wrong
When machine is idling it sits at 0 bar and get max 150 bar using front or back controls..
Is there anyway to set pressure to the pump?
How would I check the tank for blockage because it looks like the engine has to go out for the tank to be cleaned?]

 

[ahart]

Yes, pressure for the pump can be adjusted, I’d figure out why you’re not getting any standby pressure before I did anything though. There should be a drain valve right at the inlet for the pump that comes off of the suction hose from the tank, have you drained the tank there? Just wondering if it drains quick or takes forever like there’s a blockage. Low standby pressure should be 450 psi and your implement pressures should be 3000 psi. Boom lower is 2250 psi. Adjustments are done on the pump compensator valve. Margin pressure (the difference between signal and output) should be 320 psi.

 

[mrminds]

if i drain from the drain valve oil runs quick so i guess there is no blockage in the tank,
maybe i am doing the pressure testing wrong, i plugged the gauge to on the compensator quick release tab if the machine is idling gauge sits at 0 bar if steering is turned it gets to 50 bar,
the gauge sits still until any controls are touched e,g with steering it would sit at 0 bars and only start climbing from 0 to 50 bar when the steering is fully turned
how are the adjustments being done?

i bought a new valve plate & pistons will be replacing the in the morning and would like to reset the pump, maybe the pump was set either over pressure or under pressure.

 

[ahart]

Compensator pressure is signal pressure to the pump which would be 0 at standby as there is nothing signaling the pump to stroke up. Need to check main output pressure to see what standby is when pump is at idle. Also, photos of previously failed parts might shed light on what caused it.

 

[mrminds]

Compensator pressure is signal pressure to the pump which would be 0 at standby as there is nothing signaling the pump to stroke up. Need to check main output pressure to see what standby is when pump is at idle. Also, photos of previously failed parts might shed light on what caused it.

below are the pix, the operator advised that pump would make a grinding/whinning noise when in operation also and was slow in either lift or tliting on both front & rear buckets..

my gauge is plugged to the test port located below the compensator(controller) am i using the correct test port?

 

[ahart]

Outlet pressure is on block connected to the outlet line from the pump and accessed from under the machine. The signal pressure port is teed into the small line connected to the pressure compensator and is accessed by removing the floor plate in the cab.

 

[mrminds]

Outlet pressure is on block connected to the outlet line from the pump and accessed from under the machine. The signal pressure port is teed into the small line connected to the pressure compensator and is accessed by removing the floor plate in the cab.

Good day
sorry for late reply haven't really had time to work on the machine until this evening.
UPDATE: took hydraulic pump to a different workshop for repairs and was told my saddle bearings/pistons/valve plate were worn out and they replaced them and also put a new pressure compensator. was told the scouring on the valve plate might be oil contamination and advised to do a hydraulic system flush and clean off my reservoir tank.

was advised that the most economical flush was a 2-filter flush, any idea of a proper procedure to go around it
ooh and also was told the new pressure compensator might need adjustment, can't find a test port on the pump housing except on pressure compensator (A10v071 pump)

 

[stourpaine]

from those port plate pics it sure looks like damage from contamination .suggest performing a sos sample and taking in into your Cat dealer

 

[mrminds]

from those port plate pics it sure looks like damage from contamination .suggest performing a sos sample and taking in into your Cat dealer

thanks for the reply, but taking the unit to my local cat dealer would cost almost half the current value of the machine if they are to do an oil flush.

 

[Nige]

thanks for the reply, but taking the unit to my local cat dealer would cost almost half the current value of the machine if they are to do an oil flush.

suggest performing a sos sample and taking in into your Cat dealer

I get the impression that what @stourpaine was suggesting that you take an oil sanple from the hydraulic system to the dealer and have it analyzed, not the complete machine.

 

[stourpaine]

yes that's what I was meaning not sure the cost of a SOS sample these days but they used to be very reasonable and a valuable tool for diagnostics. it will tell you particle counts on various metals and dirt in your system. check the price you may be pleasantly surprised!! just remember the sample has to be taken CORRECTLY or there no value in the test. take the sample from sos test port and with cleanliness the test port should be cleaned and the surrounding area with brake clean. You will need the SOS tubing and a small adaptor the tube fits onto. also the sample bottle. now if your machine is all still tore apart you will need a sample suction gun and enough tube to reach down into the hydraulic tank and suck a sample. never dip the bottle into bucket of removed oil and don't pull the drain plug and hold it underneath. Your dealer can supply you with all these items with instructions .your report will come back possibly with recommendations' which will be highlighted in red. it could say action required or run x number of hrs and resample. if some thing is going bad internally and putting debris into the oil you will continue to rebuild pumps the test can verified what types of metals are present and steer you in the right direction

 

[Nige]

Also if you decide to submit a hydraulic oil sample for analysis make sure to ask for the test for "ISO 4406 Cleanliness Code" to be done. Some dealers include it in the analysis as standard, I don't know about Barlows, but for a hydraulic sample it's essential information.

 

[stourpaine]

slippers on the bottom of the pistons also look contaminants did a number on them too!

 

[mrminds]

I get the impression that what @stourpaine was suggesting that you take an oil sanple from the hydraulic system to the dealer and have it analyzed, not the complete machine.

noted.

 

[mrminds]

yes that's what I was meaning not sure the cost of a SOS sample these days but they used to be very reasonable and a valuable tool for diagnostics. it will tell you particle counts on various metals and dirt in your system. check the price you may be pleasantly surprised!! just remember the sample has to be taken CORRECTLY or there no value in the test. take the sample from sos test port and with cleanliness the test port should be cleaned and the surrounding area with brake clean. You will need the SOS tubing and a small adaptor the tube fits onto. also the sample bottle. now if your machine is all still tore apart you will need a sample suction gun and enough tube to reach down into the hydraulic tank and suck a sample. never dip the bottle into bucket of removed oil and don't pull the drain plug and hold it underneath. Your dealer can supply you with all these items with instructions .your report will come back possibly with recommendations' which will be highlighted in red. it could say action required or run x number of hrs and resample. if some thing is going bad internally and putting debris into the oil you will continue to rebuild pumps the test can verified what types of metals are present and steer you in the right direction

only issue now is the oil has been already drained out and discarded, the only oil left on the machine is that held in the cylinders.

 

[mrminds]

UPDATE : installed hydraulic pump but having issues with the machines response.. the rear boom swings / lifts/tilts ok
but when trying to give the hydraulic pump more power by pressing on the accelerator there is no difference,
the front/ loader lift is slow/ non responsive, only lifts fast if another control is held, checked all resolvers on the front valve bank and all white o rings look to be in good condition and removed the 2 spools and cleaned them still no difference

could it be a fault on the pump or a signal issue or other fault on the machine?

I am to fill the loader bucket with soil and lift it if 2 functions are operated and without acceleration and if I accelerate there is no difference in the speed of the lift