648g3 Hydraulic pump

CX3 · May 01, 2018, 06:47:39 PM

The pump in my JD 648g3 is making a severe whining noise. I have checked the pressure it is good. Not jumping around or anything. The pump is making a noise that you can't tolerate it will drive you crazy.

The hyd oil is running really warm. Hoses have been busting.

Can I rebuild this pump??? JD wants $4,000 for a new one! Help lol

mike_belben · May 01, 2018, 10:18:44 PM

The noise is likely to be cavitation. A high pitched whiny squeel. When the pump is pulling for more fluid than the inlet pipe is supplying for whatever reason, you get suction on the inlet side. This produced air/gas bubbles which then go into the pump gears and are pressurized, causing them to violently detonate and wear down the pump internals in the process. The sound is the harmonic of these little micro booms being dampened by the surrounding mass, which vibrate and create that noise.

Look for clogged suction screen or filter, trash stuck in a pipe, elbow or pump inlet. Collapse or folded hoses, ballvalves that need to be open etc etc.

If all this stuff checks out i guess you could have a relief valve issue but theyre usually silent. A temp gun will find the hotspot. When pressurized fluid is flowing over a leaky valve, it mskes extra heat right in that spot so probe around all over your piping and hardparts to see which area is hottest.

mike_belben · May 01, 2018, 10:19:55 PM

Any chance it is a stripped pump coupling or gear mesh failure? Gear slid on ankey and grinding into a cover or something like that?

Firewoodjoe · May 02, 2018, 08:08:19 AM

I'd get it off and have it looked at before it cracks. Got a glll right now that the hydraulic guy says we can retro fit a $1500 pump in place. Hopefully we have the details soon.

newstick · May 02, 2018, 08:45:31 PM

I would like to see that retro fit pump too. Please share if you get it figured out.

CX3 · May 02, 2018, 10:37:17 PM

Yes we are pulling the pump in a day or so and gonna have a looksy

kiko · May 02, 2018, 10:54:41 PM

Does the tone of the pump change while the boom(for example)is moving. 3000psi at rest, pressure should drop when cylinders are moving and settle back to 3000 at end of travel holding engaged.

CX3 · May 03, 2018, 11:10:02 AM

Yes when I use the blade at full capacity the noise goes away. Can't exactly remember if the grapple makes the noise go away. My mechanic said the pressures are not jumping around even under load

mike_belben · May 03, 2018, 11:17:37 AM

That is interesting. Will be paying attention to this one. Hopefully you can post pics of any carnage when you find it. Good luck

CX3 · May 03, 2018, 09:43:10 PM

I will post a pic up if we find anything. We are still trying to figure if it is rebuildable

kiko · May 03, 2018, 11:29:42 PM

If the hydraulic pressure is s remaining constant the whole time, the pump is not destroking . That problem is often found in the controller or a broken t- pin that connects the controller to the swash plate. Those pumps are repairable sometimes. The pump does not have a valve plate instead using the casting on the head as the valve plate . I have had success having a machine shop faces the head and the cylinder block if the damage is not to deep.

mike_belben · May 04, 2018, 07:33:38 AM

Ahhhh... Its a piston pump with load sensing swash plate angle to vary the flow volume output based upon flow demand by the circuit downstream.

Makes perfect sense now. The noise and heat come from all the excess oil flow going over the relief valve. Put an IR gun there and youll see the relief or just past it in the return line is hottest spot. When you call for blade the fluid demand is sufficient enough to stop going over the relief for a moment which lets it seat and quiet down.

CX3 · May 04, 2018, 08:10:30 PM

Well the mechanic said the pump is bad. There is an oil "dump" on the pump and it is draining oil quite a bit. He said this is basically a bypass and the internals of the pump are shot.

$4087 for a new pump. He said he wouldn't bother with a reman.

Who do I call for a little better price than that? Would a reman fit my need?

mike_belben · May 04, 2018, 09:44:53 PM

Can you post up some pics of the innards? Are we talking about a case drain?

You should be able to see the evidence of this shot pump with the naked eye. And for that kinda coin id insist on it.

kiko · May 04, 2018, 10:12:11 PM

Either way you go with the pump, I would want to see the innards of current pump as well, because that would let you know how much contamination has come out of the pump. Not addressing a contamination issue can get your new pump in short order and there is no warranty on a pump failure because of oil contamination. As far as your mechanic goes , sounds like he is dead on. This pump has a relief valve in the case drain that when open from excessive pressure from to much case leakage will open and allow case oil to return directly to tank with out going through the cooler. That valve also serves as a cold temp oil cooler bypass.

CX3 · May 05, 2018, 06:26:55 PM

Yes I will insist on seeing the bad part. Now where to buy one ??? Surely someone can beat a 4k dollar price for a pump I can lift over my head left handed !

kiko · May 05, 2018, 10:04:52 PM

Maybe time has changed things, but unfortunately even with the Oilgear model code John Deere could still own the rights to that particular pump. I am sure there are people that have figured an optional pump but do not know who.

CX3 · May 06, 2018, 08:15:51 AM

Well it is what it is.

Do you guys recommend JD oil for my machine or is other folks premium grade good enough?

Firewoodjoe · May 14, 2018, 07:31:05 PM

The pump we tried did not work. Everything was the same but where it went into the house. Getting a new one from Deere. $4500 I believe. Deere cat and such make it hard to get parts so u have to buy there's. Sucks.

CX3 · May 14, 2018, 10:36:43 PM

Ya I ordered one today. $4200. I called every place in America and 2 in Canada. All within about 300 bucks of each other.

Skeans1 · May 14, 2018, 10:49:10 PM

The fun of any of the big manufacturers is they can have a part locked up for them, on our 653 we were able to source one of the places Deere had sold off their stock of parts to in Ohio. If you have the part number sometimes you can source the parts of machinery trader they have a parts finder section.

mike_belben · May 15, 2018, 07:52:49 AM

Quite the racket they got there eh?

CX3 · May 19, 2018, 03:53:31 PM

Well my buggy is all fixed up. 6 new hoses. A new solenoid or 2. New heart. $9800 worth of damage. Whew. The check has been written. The sweat has dried. And I have good timber to put it on. Whew.

luvmexfood · May 19, 2018, 06:49:50 PM

Having to buy OEM parts can sometimes make you feel like your being robbed. Sort of like buying printer ink cartridges. I have bought a complete new printer, fax, copier, scanner with new full ink cartridges cheaper than I could buy replacement cartridges for the exact same model.