Cat 312 every function SLOWS when hot

[CatKC]

A purchased 312B -
When cool/cold hydraulics are strong. After working and heating up the hydraulics get weaker. Travel is slower and will not pull out of a steep area. Swivel is slower, hydraulic pump 'noise' sounds 'noisier'. Digging is less 'strong'.

As a -purchased- Cat I was wondering if 'old' hydraulic OIL might be the cause. Lower VISCOSITY under heat ?
Or . . . is the PUMP not putting out the VOLUME at higher temperatures.

45 gallons of hydraulic oil is -expensive-. . . . . as is a pump.

 

[DEMLONE70]

How many hours on ?
Serial number ?
How are filters ?
How old is the oil ?
Last know maintenace ?

 

[CatKC]

SN-9GR00434
All filters and engine oil are 2 months old.
As it was -purchased- I cannot say how old the hydraulic oil is or when it was changed.
The hour meter - shows - approx 3900 hrs. I have put about 100 on it.

 

[squidrig]

Hydraulic tank could have crud in it that's getting pulled up against the in tank strainer/ filter or suction line from tank to the pump may be collapsing or drawing in air because of the restricted filter either situation would cause the pump noise to change and a new filter in the tank with an autopsy on the old one is good peace of mind.

 

[CatKC]

Hydraulic tank could have crud in it that's getting pulled up against the in tank strainer/ filter or suction line from tank to the pump may be collapsing or drawing in air because of the restricted filter either situation would cause the pump noise to change and a new filter in the tank with an autopsy on the old one is good peace of mind.

Filter was replaced. I cleaned the removable strainer. The suction line doesn't show signs of collapsing or excessive suction.
I always do a post mortem on filters to see if there are any possible problems I should look for. None were seen.

 

[squidrig]

Does the machine gradually slow down or is it sudden?

 

[CatKC]

Does the machine gradually slow down or is it sudden?

Just seems to -gradually slow down- as it gradually warms up. I was wondering if it was low viscosity with the hydraulic oil. 45 gallons of Cat oil is expensive for a -guess-.
After it gets warmed up (it never shows HOT on the gauges) it will barely crawl up a hill and seems to lose digging pressure as well as the swivel slows.
Cold/cool it's easy to lift a track and rotate the cab, warm it will barely lift it and rotate.

 

[squidrig]

Does the machine have different work modes? If so can u hear the pump change when u switch it cold and also when it's hot?

 

[mikebramel]

Whats the pilot pressure

 

[CatKC]

Does the machine have different work modes? If so can u hear the pump change when u switch it cold and also when it's hot?

Yes it has different work modes. Yes they change speeds/pressures when hot or cold, just everything slower when hotter.

 

[CatKC]

Whats the pilot pressure

I checked the pump pressure while in Service Mode -21.
It is in the 32xx-34xx range hot or cold, which is a normal reading. I watched it while traveling hot/cold but it fluctuates too much to tell if there is much difference.

I would guess if the oil got 'thinner' as it got 'hotter' the pressure would go down as the 'volume' increased.
But if the 'pump' couldn't keep up with the increased 'flow' it would indicate the same.

I was hoping someone could tell me if it has the symptoms of a worn pump or just an oil change.

 

[DEMLONE70]

Block the tracks to check pressure
What oil is in the tank ?
What about the rmp of the engine ?

 

[GregsHD]

45 gallons of Cat oil is expensive for a -guess-.

No need to buy that fancy CAT barrel, any quality brand ISO32 or ISO46 (depending on your climate) hyd oil will be fine. This is a Catsubishi after all.

I would say since you don't know when the hyd oil was last changed it would be money well spent, and piece of mind.

 

[DEMLONE70]

Cat don't use ISO32 or ISO46

 

[CatKC]

Block the tracks to check pressure
What oil is in the tank ?
What about the rmp of the engine ?

Someone checked the pressure with tracks blocked a while back for a slow/fast travel problem (which turned out to be the pressure sensor) and said it was good but didn't say what it was. I'll have to see if I can read the RPM from the console, but it -increments- each throttle position 1-10 and doesn't 'sound' slow or bog down.

 

[CatKC]

No need to buy that fancy CAT barrel, any quality brand ISO32 or ISO46 (depending on your climate) hyd oil will be fine. This is a Catsubishi after all.

I would say since you don't know when the hyd oil was last changed it would be money well spent, and piece of mind.

I had an oil analysis done after I purchased it to see if I might have some 'impending doom'. The particles were good and the cSt at 100degC was 7.1 which would indicate a 20w viscosity. The 40degC was 47 which would also indicate a 20w.

I have heard and read so many things about hydraulic oils. Some hydraulic equipment uses engine oil, some transmission oil. I understand unlike engine oil, hydraulic is in a 'sealed and contained' environment (unless you have external connections) and needs to 1-lubricate 2-not foam 3-disperse moisture. I'm not convinced Cat oil would work better than a good quality oil of another brand.

 

[DEMLONE70]

Your problem has nothing to do with oil

 

[CatKC]

Your problem has nothing to do with oil

Thank you- I was thinking it may not be oil after finding a specification of Cat oil online. Their HYDO Advance 10 has less viscosity. ( 42cSt at 40gegC - 6.7cSt at 100degcSt)

I need to check one thing you asked earlier, the engine RPM hot and cold. It sounds the same cold/hot but sounds are sometimes deceiving.

 

[92U 3406]

Is it possible to check pump case drain volume? If pump has excessive internal leakage you'll lose speed on all hydraulic functions. Pressure reading isn't the be all end all factor of pump condition. If you don't have adequate oil flow, you'll have slower speed. I'm not near my laptop for the next couple days unfortunately, so I can't check SIS.

 

[CatKC]

Your problem has nothing to do with oil

Yesterday I checked the engine RPM. The maximum was 1800 RPM. Just for grins I went into service mode and did a Governor Actuator Auto Calibration (70) and a PS Signal Calibration (71) . The maximum is now a little over 2100 RPM.
I did some work with the Cat and it did not loose power or slow down. I don't know if it is fixed or not but so far it looks good.