Bobcat 632 trans light flickering

[Macguver]

First time poster here. I'm helping a neighbor with his really well kept 632. The machine runs nice all around. The problem he's having is the trans light will flicker on and off if your pushing into a pile of dirt and lifting the booms at the same time it also sounds like it has a brief sound of air when the light comes on.It won't do it unless your working the hydraulics. If you lift the booms up easy while driving into the pile it will not come on. The pressure switch was replaced four years ago. Tonight I took the bronze filter out and cleaned it. It had some stuff on it but not bad. How do you check the charge pressure? Could the vane pump be getting weak? How do you check that? He owned the machine for 15 years and has been trouble free. All other hydraulic functions work great with no issues. Thanks in advance.

 

[Bswwood]

Two things make the trans light come on, low hydrostatic pressure and high hydraulic oil temp. Could be weak pump but not sure what the "air" sound is. Could it be a weak relief in the hystat pumps bypassing? What happens when you hear the air sound, do you loose any functions? Does it only do it in a pile going forward or can you work functions in reverse and get light to come on? Does it dive strait or does one motor feel weak? You can remove the charge pressure sensor and plumb a hose and gauge to run outside cab so you can see it while operating the machine to double check charge pressure. The questions I am asking will help narrow down where to look next like relief or replenishing valves.

 

[Macguver]

Two things make the trans light come on, low hydrostatic pressure and high hydraulic oil temp. Could be weak pump but not sure what the "air" sound is. Could it be a weak relief in the hystat pumps bypassing? What happens when you hear the air sound, do you loose any functions? Does it only do it in a pile going forward or can you work functions in reverse and get light to come on? Does it dive strait or does one motor feel weak? You can remove the charge pressure sensor and plumb a hose and gauge to run outside cab so you can see it while operating the machine to double check charge pressure. The questions I am asking will help narrow down where to look next like relief or replenishing valves.

Ok thanks for the info. Yes it does it in reverse also. Only comes on when you are moving and raise the booms up fast. So there has to be a big hydraulic demand for it to come on. The light might come on for a second when it comes on. It also only comes on 1 out of 5 times raising the booms when your moving. If your sitting still the trans light will not come on while raising the booms up fast.The machine has always favored the right side since he has owned it. Has good power to wheels it will spin down in the dirt.What should charge pressure be? I will get a hose made up and report back. Thanks

 

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Ok thanks for the info. Yes it does it in reverse also. Only comes on when you are moving and raise the booms up fast. So there has to be a big hydraulic demand for it to come on. The light might come on for a second when it comes on. It also only comes on 1 out of 5 times raising the booms when your moving. If your sitting still the trans light will not come on while raising the booms up fast.The machine has always favored the right side since he has owned it. Has good power to wheels it will spin down in the dirt.What should charge pressure be? I will get a hose made up and report back. Thanks

my old 643 used to do this every once in a while. when working it hard into a pile. i asked the question on here and tazza said his machine did it too, and i never paid attention to it again. worked the machine for another 5 years before i traded up to an s130.

 

[Bswwood]

Ok thanks for the info. Yes it does it in reverse also. Only comes on when you are moving and raise the booms up fast. So there has to be a big hydraulic demand for it to come on. The light might come on for a second when it comes on. It also only comes on 1 out of 5 times raising the booms when your moving. If your sitting still the trans light will not come on while raising the booms up fast.The machine has always favored the right side since he has owned it. Has good power to wheels it will spin down in the dirt.What should charge pressure be? I will get a hose made up and report back. Thanks

I agree with the other post, probably be fine for many years to come, however sometimes its nice just to get to the bottom of the issue. The charge relief should be set to 85-90 PSI. If it is low you can remove and inspect the charge relief first. I know the sensor was replaced some time ago but it could still have an issue.