Charge pressure issues

[Mikefromcny]

Has anyone had to replace a charge pump on a bobcat? Reason I ask is I've seen several machines have low charge pressure issues, but never heard of anyone replacing the charge pump. My S250 started acting up last night. For the past 6 months, Occasionally the low charge pressure light would come on, usually when cold. Shut off and restart it and it was good for the rest for the day. Last night, shutting it off and restarting it didnt help, as it kept coming on. Anything I should check? Plan on checking drive belt tension today, along with swapping charge pressure senders.

 

[Mikefromcny]

I forgot to mention drive, boom, curl functions work fine. Occasionally a belt would squeel when it was cold, drive belt seems to be tight.

 

[Tazza]

I forgot to mention drive, boom, curl functions work fine. Occasionally a belt would squeel when it was cold, drive belt seems to be tight.

There is no dedicated charge pump, it is done with the returning oil from the main hydraulic pump. I'd scart with the hydraulic filter, if it keeps happening, hook up a gauge to check what it is, don't fully trust a sender, they do go bad.

 

[Mikefromcny]

There is no dedicated charge pump, it is done with the returning oil from the main hydraulic pump. I'd scart with the hydraulic filter, if it keeps happening, hook up a gauge to check what it is, don't fully trust a sender, they do go bad.

Thanks tazza. Charge pressure sender (the one near the valve block) has been replaced with no difference. Hydraulic filter has 10 hours on it.

 

[Bobcatdan]

Thanks tazza. Charge pressure sender (the one near the valve block) has been replaced with no difference. Hydraulic filter has 10 hours on it.

I put a gauge on it and check actual pressure. If low it can be adjusted. Since you say everything works fine, I'd think your pressure is fine. You may have a fun 5 volt circuit problem. One sensor can throw the system off and controller doesn't know for sure what is going on so it just guesses.

 

[Mikefromcny]

I put a gauge on it and check actual pressure. If low it can be adjusted. Since you say everything works fine, I'd think your pressure is fine. You may have a fun 5 volt circuit problem. One sensor can throw the system off and controller doesn't know for sure what is going on so it just guesses.

Update: the results are in.. Started the machine up tonight, Sat in it and waited until it did its nonsense. I got the following codes in this order...05-09, 05-14, and 05-15. Built an adapter out of a 3/8 x 24 fine thread bolt. I threaded a nut on to it, cut a groove in the threads for the o-ring. Put said bolt in the lathe and drilled a hole through it. Welded a pipe nipple to the bolt, hooked it to a grease gun hose and attached a 1000 psi gauge. I got 395 psi at warm idle and around 420 psi wide open. Does this seem okay for charge pressure?

 

[Bobcatdan]

Update: the results are in.. Started the machine up tonight, Sat in it and waited until it did its nonsense. I got the following codes in this order...05-09, 05-14, and 05-15. Built an adapter out of a 3/8 x 24 fine thread bolt. I threaded a nut on to it, cut a groove in the threads for the o-ring. Put said bolt in the lathe and drilled a hole through it. Welded a pipe nipple to the bolt, hooked it to a grease gun hose and attached a 1000 psi gauge. I got 395 psi at warm idle and around 420 psi wide open. Does this seem okay for charge pressure?

Spec is 410 to 470 at 140° at fast idle. There really isn't a low idle spec. If I remember correctly thou, a code won't trigger until pressure is down near 300 psi. It can be adjusted by shimming the charhe pressure relief vavle. I'll read threw your codes, you may have a 5 volt problem.

 

[Bobcatdan]

Spec is 410 to 470 at 140° at fast idle. There really isn't a low idle spec. If I remember correctly thou, a code won't trigger until pressure is down near 300 psi. It can be adjusted by shimming the charhe pressure relief vavle. I'll read threw your codes, you may have a 5 volt problem.

Codes are all charge pressure, I'd check wiring and swap controllers.