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Bobcat  > Excavators  > 328 Hyd pump sucking air  
 
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 Author Thread: 328 Hyd pump sucking air
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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328 Hyd pump sucking air
Posted: 04/13/2012 07:30 PM

I have a customers 328 here for some work, has @ 2800 hours, needs some pin work and tlc, but I'm more concerned about something he never really wanted fixed, but after discussing with him its clear it needs it. The hydraulic jerk on all joystick function, and the oil in the res gets foam in a heart beat after start up.

I can't see any leaks in the suction side of the system and it should leak as the pump is below the fluid lever. How common is it for the sear around the pump shaft to fail, is it usually a seal only or time for a new pump?

I have yet to dig into the manual, just wondering if anyone has any thoughts on this.

Ken


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
7LBSSMALLIE is not online. Last active: 8/20/2014 8:52:10 PM 7LBSSMALLIE
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Re: 328 Hyd pump sucking air
Posted: 04/13/2012 08:42 PM
not to many folks rember how to find a suction leak i bet old m knows i posted this on tip and tricks good old fashioned shaving cream place on suction lines , find dimple there is youre leak. seems stupid but eaisley discernable,
Tazza is not online. Last active: 8/26/2014 2:14:24 PM Tazza
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Re: 328 Hyd pump sucking air
Posted: 04/15/2012 05:42 PM

Keep in mind that a restriction in the suction line can cause bubbles. My 731 with a blocked suction line filter had this problem when i first bought it.

Just another thing to look out for.

I like the idea of shaving cream for finding a leak, simple, yet effective.


Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 04/16/2012 03:02 PM

A couple thought to try, guess I'll just have to dig into it. Routing of the suction line is a major pita, getting the pump off does not look any better.

Oh well have to get this bleeding 743 out of the shop then the X is next


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
Fishfiles is not online. Last active: 2/23/2014 3:44:14 AM Fishfiles
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Re: 328 Hyd pump sucking air
Posted: 04/16/2012 03:38 PM
Maybe it is not sucking air , maybe it is creating air , cavatation produced from wear on the  plate of the pump  a flow and working pressure test might  show you something
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 04/24/2012 06:09 AM

Well picked up a flow meter from a friend, so see ho that goes, but cant see it passing the test when the supply gets all airated. Going to try running it low rpm and with no pressure (just sitting still) to see if it foam or not like this.

They have been running it like this for awhile, even had to low the res level as it was boiling out. Thinking the pump is likely dead.

Ken 


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
Fishfiles is not online. Last active: 2/23/2014 3:44:14 AM Fishfiles
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Re: 328 Hyd pump sucking air
Posted: 04/24/2012 06:13 PM
you saying it was bubbling out the tank made me think back on something I seen really freaky happen once ,   it was on a 7 seried Bobcat and the screen in the hydraulic tank fill neck was gone and they had dropped a piece of hose from the bottom of a funnel into the tank and just forgot about it , it was in the supply hose and sticking up in the tank I'd guess above the fluid level and sucked in air  I found while taking out the gear pump when I pulled the hose off the bottom of the tank to get it out the way -----------I doubt you'll see that , I think the pump is really trashed  to boil it over with air bubbles
7LBSSMALLIE is not online. Last active: 8/20/2014 8:52:10 PM 7LBSSMALLIE
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Re: 328 Hyd pump sucking air
Posted: 04/24/2012 08:31 PM
i concur have seen this once ,on a 7 serrieries but still applicable drain and clean tank. look for obsttructions. exv dont normally suck air ,Note they are apressurizied tank for a reason . there is an air bleeding procdure if you need ill get it to you but normally youre basic work the functions will get itt out in extremes take load sense line loose at control valvve hose to tank, and run at idle till clears up tech licanily you are supposed to filter , as in part number who gives a sh*t. dude run a hose from load sense back to tank .run for 15 cycling all ffunctions air should bleed,
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 04/25/2012 03:38 PM

#2 and # 3 section would both push 2250 psi when I bottomed the function.

#1 1500psi at idle, 2050 reved up. This is with oil @ 90f

The E seal was gone inside the pump at the back side of the first section. All sections have a ridge where the gears run in the inside outer body, but #1 is the worst.

Further this is a throw away pump, nothing but seals available as parts. $1275 will get me a fresh one at the dealer. LPS can't get them.

Doubt there is any other source?

 


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
7LBSSMALLIE is not online. Last active: 8/20/2014 8:52:10 PM 7LBSSMALLIE
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Re: 328 Hyd pump sucking air
Posted: 04/26/2012 06:58 PM
good job fininding issue, after install of new pump dial in pressures to hi side of spec. you will be happy with change in performance 1 or 2 hundred psi world of differance at sticks.
Tazza is not online. Last active: 8/26/2014 2:14:24 PM Tazza
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Re: 328 Hyd pump sucking air
Posted: 04/26/2012 08:39 PM

That's the worst thing about gear pumps. As the bearings wear they start to chew the pump housing. The more they wear the more they eat it. You replace the bearings, your pressure drops of as the clearance between the gears and housing are wrong. Vane pumps compensate for this with the vanes just extending slightly further.

I guess its the nature of the beast. Just a shame its such an expensive repair....


Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 05/02/2012 06:41 PM

After a few phone call I found a dealer that threw me a bone on some Bocat promotion coming up that offers 15% off, so got a new one for $1083

Still spendy but better.

If you need genuine parts now might be the time to hit your dealer up. Its still coming as they can't bill me tll the 11th I believe.

Still waiting for it, wlled up a slack pin hole in the main swing pivot today.

Going into the crowd pivot point next.

Ken


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 05/17/2012 06:27 AM

Update

Finally got the new pump a week ago and they changed the outlet ports from orb to flange. So finally got the flanges and installed it yesterday. Had to let the trapped air out at the suction of the pump, then the pump circullated oil in the tank. Naturally full of air at first, but getting better with each run/sit cycle.

Problem is some functions have no pressure, so where is the bleeding to be done from 7lbsmallie?

Right now the tracks won't turn, even in the air, the bucket and thumb are lazy and the boom seems to lift ok (at least makes the motor labour a bit when hitting the end) but won't begin to lift the machine on the down side. Blade and crowd boom have good pressure.

I'll start looking through the manual for bleeding procedures....

Thanks

Ken


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
Bobcatdan is not online. Last active: 6/1/2014 11:45:49 AM Bobcatdan
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Re: 328 Hyd pump sucking air
Posted: 05/17/2012 08:23 AM
What is the serial number?
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 05/17/2012 10:48 AM

516612xxx

Wondering if i swapped a #8 hose, but there are just the 3 pump outputs and the one to the block between #2 and #3 pump. I should have labeled them, but they where all sitting in order, the outputs with elbows pointing up and the 4th line sideways.

Ken


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 05/17/2012 06:28 PM

Well I hooked in a pressure guage to #3 section and I got nothing, not even 50 psi. It will pump oil out the open line but appears to have minimal pressure.

Never dawned on me at the time, but while connecting the guage to the fitting oil was flowing through the pump. A gear pump should not free flow?????????

Something must be assembled wrong between section 2 and 3. This is the pump that has the check valve port block between section 2 and 3. Also 2 and 3 share a common suction hose through a port iside the pump. Where as #1 has its own inlet.

 


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
7LBSSMALLIE is not online. Last active: 8/20/2014 8:52:10 PM 7LBSSMALLIE
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Re: 328 Hyd pump sucking air
Posted: 05/17/2012 07:20 PM
back up and pump referance the s/m for checks .(punt) start from scratch. identify what pump does what? trace youre hoses as per hyd schmetaict referance the parts man for con firmation. you sound completley lost as a pro nothing is worse than a unit that is not factory. NIGHTMARE., IN THE MAKING , with history first i would have to confirm that plumbing is correct,(hopefully you went with oem hoses that have part #s stamped in fittings,. if not well . back to scratch it can be done. . jimmy joe blow hack jobs, are not in youre favour, at 9745 an hr fixing hacks gets expensive.. oem parts hoses etc have # stamped on fitting. can be traced this way. if one hose outa 45 is wrongly plumbed (easliy done) world of hurt.
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 05/18/2012 05:10 AM

The brand new pump I have makes no pressure on sections 2 and 3. I removed the guage from the from the line conected to the test port on #3. On the starter it won't even lift the oil up to run out the open hose back into the top of the hyd fill. With the engine runniing I can hold back the flow coming out of this hose with my thumb, maybe 5 psi. (not flying out the line like its going to empty the tank in 60 seconds) No wonder my guage with the 1st graduation at 100 psi won't even wiggle the neeedle.

Guess its time for another new pump. Haldex must not test these??

Smallie, I hear you, but I drove this thing in the shop and it basically worked other then foaming the oil. The only hoses that have been off are the 6 on the pump. 2 suctions you can't screw up, 3 outputs, #8 jic F with 90's up from below, and the check valve line that comes in from the top, also #8 90. But if the pump makes no flow it does not matter what line you hook to it.

Ken


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
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Re: 328 Hyd pump sucking air
Posted: 05/18/2012 11:23 AM
My two cents: even if I did not work for a dealer, something as major as a pump I would only get a factory replacement. A lot of this stuff is built to OEM spec and even thought the basic same pump is used on brand A and B, there are likly differenc one can't see. Bobcat is veray good at using say size 5, 4 and 6 are common as dirt and 5 just don't exist outside of Bobcat.
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 05/20/2012 08:01 AM
It is a Bobcat oem pump, made for them by Haldex. I did check with LPS initially but they were unable to source. They are oem only.

NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
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Re: 328 Hyd pump sucking air
Posted: 05/20/2012 09:04 AM
It sucks when something brand new doesn't work. Apples to oragnes, it one took bobcat four tries to get me the right knuckle for a toolcat. It was back order for three months to begin with, then it shows up, right number on the box, wrong side. This happen two more times before I got the right one.
Fishfiles is not online. Last active: 2/23/2014 3:44:14 AM Fishfiles
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Re: 328 Hyd pump sucking air
Posted: 05/20/2012 11:01 AM
you saying that it is free flowing oil thru the outlet port would suggest to me that seals are blown or excessive wear inside the pump , could have been  a bad build , I think I would open the pump to determine what caused the failure ----------- to get another pump and install it then it does the same thing again from a cause that has yet to be found wouldn't be nice
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Re: 328 Hyd pump sucking air
Posted: 05/24/2012 10:19 PM

Fishfiles

Its not even a rebuild, it is brand new, so I'm not going to give them any excuse to hang it on me.

It took 10 minutes for that one 8 gpm section to pump the 6 gallon reservoir dry, through a 3/8 hose on the test port. Though the machine was at a idle.

It makes no pressure, guessing @ 5 psi Like they forgot to install one of the gears.  


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
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Re: 328 Hyd pump sucking air
Posted: 05/25/2012 03:13 AM
I never used the word ( re ) build , the word was build , that new pump was assemblied  ( built ) by some one some where , during that assembly ( which may have been in Medico for all I know , it could have be improper built ------------ something else that could have fried it was that it was not primed up or trash was still in the system from the first failure -------what I was saying is make sure it's all right before you trash another pump as they will probally warranty this one but if it happens again it could become  a mess
7LBSSMALLIE is not online. Last active: 8/20/2014 8:52:10 PM 7LBSSMALLIE
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Re: 328 Hyd pump sucking air
Posted: 05/25/2012 09:32 PM
looking over posts what we neglected was the brass filler screen in hyd tank. is it thhere pull tank and dump it. i did not read all posts at this time.having a beer in garage, let us start again we have a three section hyd pump one or more is introducing air into hyd sys cauising cavatition. as edvinced by foamy oil, is this correct
7LBSSMALLIE is not online. Last active: 8/20/2014 8:52:10 PM 7LBSSMALLIE
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Re: 328 Hyd pump sucking air
Posted: 05/25/2012 09:40 PM
now lets isolate, start by identi. function of eaach pump. let cool and un foam, you follow? is it travel .work group or charge, this may aid in identifactioj of problem. isolate
7LBSSMALLIE is not online. Last active: 8/20/2014 8:52:10 PM 7LBSSMALLIE
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Re: 328 Hyd pump sucking air
Posted: 05/25/2012 09:45 PM
if this landed in my lap i would do a direct pump test on all three. i would dial in all pressures to high side of spec. and than check operation.
skidsteer.ca is not online. Last active: 7/21/2014 8:31:40 PM skidsteer.ca
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Re: 328 Hyd pump sucking air
Posted: 05/30/2012 08:05 AM

The original pump was foaming from a bad E seal, but had some wear. However system was not contaminated and the was plenty of flow to the pumps suction. Customer decided on a new pump over reseal job on 2800 hour pump. No hard parts are available.

New pump foamy oil problem gone, but only made pressure on 1 section. The other 2 had none. I could stop the flow with my thumb over the output line,(so pointless to flow test) basically the oil was running via gravity  from the tank through the pump on section 2 and three, starting the engine just sped this process up a bit.

Unfortunately I had to leave it in the hand of a mechanic friend, as I have taken a new job 1100 miles away, 2 weeks out, 1 back home.

So I just called him so I could update you all. Drum roll.... when you turn the input shaft on the pump, sections 2 and 3 do not rotate.

Between the pump sections (I pulled the old pump down) are short splined drive shafts to continue the drive to the next section, one must have be left out in assembly.

So Fish you hit the nail on the head. My apologies for mis reading what you said earlier.

Dave does not have the unit up yet, because when I crossed the engine lube filter from Baldwin to Wix they gave me the wrong part (bad wix! Screams “why me“, can't catch a break, and I even double check the # because the filter was a bit smaller, the cross reference is wrong) so he is just waiting on a lube filter and has to put the counter weight back on.  Pretty sure it will be all good now.

This “may” be why I won't miss being a mechanic at my new job as a operator.. only a operator, dont even touch the dip stick!!! (Union)

Although I gave the fuel/lube guys a heads up on low hyd oil on my loader and the prick had the nerve to say “just stand back and let us do our job”

I just about told him to STFU and pay attention, your talking to a licensed mechanic “pumpboy”, but I'm new there , so I though I had better behave myself. (and I have a few weeks to go b4 I write the goverment test)

I got to meet the equipment manager the next day, he is a great guy and we hit it off. In a few minutes of talking he was glad to have me and we are on the same page.

And I'm sure the mechanic thing is like a disease, and I'll be back at it at some point, hopefully with this new company.


NH LS 160, S150, S185 Hoe Brusher Grapple Auger, Mixer Tiller Soil Conditioner Trencher Tracks Snow Blade Wood Splitter Stump Grinder Land Plane. Dealer Virnig Erskine Componets Plus Wallenstein Bauma Lite
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Re: 328 Hyd pump sucking air
Posted: 05/30/2012 08:37 PM
Congradulations on the new job Ken , I am a member of The International Brotherhood of Operating Engineers Local 406 since 1976 , my Dad was a member for 53 years , I was lucky enough to have been an apprentice as a mechanical  engineer , I have not work thru the union for quite some time as I am self employed but learned alot and made good money doing it  and enjoyed my job ---------  good luck ------ever figure out where that pump was built (assemblied) probally Bangcock
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Re: 328 Hyd pump sucking air
Posted: 05/30/2012 10:10 PM
glad you got it squared away. but you shame us all when you state that as an operator you dont have check the dip stick. first line of defense ,operator shame on you unless lube truck is there prior to work day. start. walk around fluid check or walk away id fire youre a$ the first time i watched you,
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