950H Fan rotating slowly, Coolant overheating

[GuhanK]

Recently we faced overheating complaint in 950H loader, Radiator was cleaned, thermostat replaced,
Piston pump for brake & hydraulic fan pressure tested, It shows that the pump port pressure & load sensing pressure is 1600psi at low idle(Engine fan bypassed to 100% using CAT ET).The difference is zero(Margin pressure).High pressure cut off is 2100psi with Fan solenoid disconnected & at high idle.
The service brake pressure is 600 psi at high idle. Control manifold(Charging valve) cleaned and fitted. But the problem was not resolved.
So kindly advise.

 

[Nige]

Have you looked in the hydraulic lines connecting the flow control valve to the fan pump for the presence of a filter/screen..? I seem to recall that there was a screen on that particular hydraulic circuit that looked very much like a pipe connector and no-one ever realised what it was. Most of the time slow fan speed (low flow to the pump in other words) was caused by the fact the screen was almost plugged solid with accumulated debris. It was not mentioned in the PM schedule for the machine either.

 

[kshansen]

Have you looked in the hydraulic lines connecting the flow control valve to the fan pump for the presence of a filter/screen..? I seem to recall that there was a screen on that particular hydraulic circuit that looked very much like a pipe connector and no-one ever realised what it was. Most of the time slow fan speed (low flow to the pump in other words) was caused by the fact the screen was almost plugged solid with accumulated debris. It was not mentioned in the PM schedule for the machine either.

I tried to see if I could find this filter in a parts diagram but seems to be a few different S/N prefixes so not sure which one to look at.

 

[Mark250]

hi,the screen is in the control manifold under the fitting for the pump inlet, i think from memory that if that screen blocks up it is an indication of pump failure and it generally affects the brake circuit,
also your brake service pressure is low (600) should be about 1000 psi.if you have a brake circuit pressure loss the priority valve will isolate the fan circuit until the brake circuit is satisfied
mark

 

[GuhanK]

950H Fan rotating slowly

The serial no is JAD00620

 

[jett01]

Hello , trying a goggle search for our 950H turned me to this post as i am having the same problems where the fan is not turning fast enough to cool the engine . I am having trouble finding the screen Nige is talking about . We did replace the pump as the old one was completely gone . I did buy a good used from caterpillar dealer but maybe now it is gone too . the brakes do work fine however the ebrake is eratic where it will come on unexpectedly while just idleing . my thought is that there is swarf from the old pump rolling around somewhere maybe hopefully trapped at the screen . thoughts advice etc

 

[jett01]

Hello here is the serial number

 

[Nige]

See Mark's post #4 above. He describes the exact location of the screen.

 

[jett01]

If this is the manifold I took it all apart and I can’t find a screen, this is the old pump.

 

[ahart]

See below for location of screen. Control valve is referenced by “A” and screen is item # 8
The part you are pointing to in your photo is the compensator for the pump, controls the outlet volume of the pump.

 

[jett01]

Yes I know Exactly where you’re talking about. I will investigate and let you know what I come up with thank you so much ahart