843 hyro pump noise

[Mahere]

I have an older bobcat 843, I have gone through and done a total rebuild of the engine. When I wend to put it back in I also put in a new u-joint connection between the pump and the engine "per a recommendation from bobcat that no one ever greases the joint". The engine runs great but I started to use the machine and I am getting the high pitched low fluid squeal, and shortly after that turned into a knocking and clunking. The machine looses power and sounds so horrible I am trying not to run it much. I thought the joint went bad but it did not. In the process of rebuilding parts of this machine I drained and cleaned the hydraulic tank, installed new fluid and filters. From a few things I read on here I am leading to a need a new pump does any one have any thoughts?

 

[Tazza]

I'd like to confirm where the knocking and clunking noise is coming from, it is the engine or the pump? Ideally run the engine when it's not hooked up to the pump.and with the coupler removed.
I don't believe these pumps are cheap as the wear parts inside can't simply be replaced, they need building up, hardening and grinding. Loader parts source will have the parts you need or even get your parts repaired.
You need to confirm where the issue is though, enging or pump. If it's the pump, you should crack it open and see if you can find the issue.

 

[Mahere]

I'd like to confirm where the knocking and clunking noise is coming from, it is the engine or the pump? Ideally run the engine when it's not hooked up to the pump.and with the coupler removed.
I don't believe these pumps are cheap as the wear parts inside can't simply be replaced, they need building up, hardening and grinding. Loader parts source will have the parts you need or even get your parts repaired.
You need to confirm where the issue is though, enging or pump. If it's the pump, you should crack it open and see if you can find the issue.

The clunking and knocking is coming from the pump its self. I have yet to remove the pump, a few people told me to do a pressure test but I do not know where on the machine to tap in for that test. Can you tap in any where? I looked into the new drive pump from bobcat and it comes in at a scary $6,800 if they can even get it for the older machine, plus $1,100 for the pump that does the boom and bucket. Does any one know a reliable place that I can send the pump to for rebuilding once I take it out? A friend suggested Fluidpowerservice.com in up sate NY.

 

[Tazza]

The clunking and knocking is coming from the pump its self. I have yet to remove the pump, a few people told me to do a pressure test but I do not know where on the machine to tap in for that test. Can you tap in any where? I looked into the new drive pump from bobcat and it comes in at a scary $6,800 if they can even get it for the older machine, plus $1,100 for the pump that does the boom and bucket. Does any one know a reliable place that I can send the pump to for rebuilding once I take it out? A friend suggested Fluidpowerservice.com in up sate NY.

www.loaderpartsscource.com can do it too.
Parts are still available, i just don't know what could be causing the knock. It is possible that the universal joint between the pump and motor is damaged, this could make noise.
To test pressure/flow you need special gear. To just test pressure, you tap into the aux hydraulic connector and install a 3,000 PSI gauge and operate the hydraulics. This is the main hydraulic circuit, not the drive system. The drive system can be checked by removing the lines to the motors and installing a 5,000 psi gauge you can then operate the drive system and see what pressure you get.

 

[Mahere]

www.loaderpartsscource.com can do it too.
Parts are still available, i just don't know what could be causing the knock. It is possible that the universal joint between the pump and motor is damaged, this could make noise.
To test pressure/flow you need special gear. To just test pressure, you tap into the aux hydraulic connector and install a 3,000 PSI gauge and operate the hydraulics. This is the main hydraulic circuit, not the drive system. The drive system can be checked by removing the lines to the motors and installing a 5,000 psi gauge you can then operate the drive system and see what pressure you get.

When I rebuilt the engine, after talking to bobcat parts guy I replaced that entire universal coupler set up. How ever some one told me that maybe a bolt came out and it was not installed with lock tight. I will have to check that tonight and see if maybe that is part of the problem. Even if that is the cause of the knocking noise then maybe there are still other problems with the pump that cause the squealing and power loose. I do not have the gauges to do that so I may need to check into the universal and then see about getting my machine to a shop and see if they can run those test and see what other issues are there.

 

[Tazza]

When I rebuilt the engine, after talking to bobcat parts guy I replaced that entire universal coupler set up. How ever some one told me that maybe a bolt came out and it was not installed with lock tight. I will have to check that tonight and see if maybe that is part of the problem. Even if that is the cause of the knocking noise then maybe there are still other problems with the pump that cause the squealing and power loose. I do not have the gauges to do that so I may need to check into the universal and then see about getting my machine to a shop and see if they can run those test and see what other issues are there.

I'd like to think the universal is good if you replaced it, but it can happen. I had one that i did and the bolts were a bit tight, this caused vibration as it was holding the spider a little funny causing it to not move in one way correctly. Took a skim off the bolts in my lathe and it was good as new.