what do these symptoms tell me?

[dodgeking7131]

Hey guys so heres what im trying to figure out.

I have a 70s Hydra mac 18. I havnt had it long, lift always was "slow" but figured it was age of machine but it all worked as it should. but now i have some symptoms that i need some help with.

If i leave the loader sit the hydraulics loose their prime. IE the arms wont move buck doesnt move then they kick in.

Arms are slow and i think getting weak. takes mmm 15-20 secons to full extension and seems to have issues with bucket breakout or even tipping the machine ( im trying to remove a walnut stump)

after the machine is ran and oil is hot ( im not sure how hot it is but its warm) it almost wont pick up at all.

if i leave the boom up over night it might sink a few inchs but nothing that i would be worried about especially with its age.

I changed the filter thinkin it might be restricted. the feed comes from two seperate tanks ( feeds from chain case) so i dont think there is a restricted flow.

Im stuck between a bad relief valve or bad pump. i dont THINK the spool valve is bypassing being the bucket stays up over night. and its also not consistent. Yesterday
the arms were so worthless that i just quit. today they always worked enought to get work done.

I havnt put on a meter or anything, I dont have one nor am i sure where i want to install it.

Thanks Guys

 

[DLTTrekkers]

Normally bad pump

 

[J_J]

I would recommend a pump flow and pressure test.

A hyd shop can do this.

A flow meter is not something the average person would have, but a pressure gage could be installed and would help you troubleshoot the hyd system.

The 3000 psi hyd gage can be installed in a tee at the IN port of the first valve after the pump.

 

[Egon]

After the hydraulic oil is hot check some of the lines downstream from cylinders and PSV's and check how hot they are. Might give you an indication of flow?

 

[J_J]

Check the loader relief valve and see if there is any debris keeping the valve open.

Check all the QD's.

Check any sump filters and all filters.

If you have no or little power, and the cylinders and reliefs are good, then the pump is probably the cause from lack of pressure potential.

 

[dodgeking7131]

j_j what is a qd? there is a auxilary single spool valve before the main bank. but i dont see any relief build int ( atleast not adjustable") Ill install a pressure gauge into that and see what we can find. The hydraulic pump is a Borg Werner ( obsolete) with a part number s30s17ah11r, trying to find a replacement has been hectic haha

Can you just remove the pressure regularor usually without any harm? ive never bene in one and i dont want some ball bearing rolling down into the system.

 

[dodgeking7131]

also, can i install a pressure gauge in one side of the auxilary line? it would be dead headed but i ive hit the pedal many of times and never blew anything * maybe thats my problem* so i would think the dead head would not be a problem

 

[J_J]

QD = Quick Disconnect A hyd fitting that will block fluid when disconnected.

The pump might have a relief valve built in.

All hyd components need to be under a relief valve, as the pump will keep on trying to build pressure.

You can plug a pressure gage in a QD to check the pressure momentarily.

 

[dodgeking7131]

One more symptom to throw out there. If I am trying to lift the weight and it struggles. I can work it like a jack if that makes sense. I mean if I center the spook valve and the. Move it back to into the working direction the cylinder will raise a few inches then stop again. Then i re center and do it again. Sounds like a real valve eh?

 

[J_J]

When you have a load in the bucket, the cyl could be leaking some, and when you move the lever for more, then the pump tries to develop the pressure up to the relief pressure.

You can also tilt your bucket up and gain some lift as you change the balance point.