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980H No hydraulics on start up

Discussion in 'Wheel Loaders' started by JakeHarrington, Nov 23, 2019.

  1. JakeHarrington

    JakeHarrington Active Member

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    i have a 980h JMS03132. it has 12,000 hours on it. i bought it used 2 months ago. i have the half wheel command steering.
    now in the colder weather when i start her up every morning I can't steer or move the hydraulics. it takes like 20 minutes of idling till i can steer. and then another 10-20 minutes of run time till the steering and hydraulics are smooth.

    i have plenty of oil in the hydraulic tank. i have no codes on Cat ET.

    It sounds like it sucking air almost but i can't find any leaks.
    the hydraulic tank doesn't build up much pressure while running. i have rigged up a test port and a gauge in line with the breaker valve on the tank. i was told that these tanks are supposed to be pressurized.
    when i rig up a fitting and put 10-20psi in the tank on start up the hydraulic start to response much quicker then normal(2-3mins).

    i believe my problem is somewhere in the pilot control system.

    Any help would much appreciated.

    thank you.
     
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  2. Nige

    Nige Senior Member

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    Kudos for posting a Serial Number - most people don't.
    What viscosity of oil do you have in the hydraulic system.? From the symptoms you describe it sounds as though it's too heavy. The clue is that once the machine has warmed up it sounds as though it works fine.
    The breaker relief valve is a 220-0814 (CRB 507-0644) which is specified as 10psi give or take. Thing is when the oil is cold the tank will have little or no pressure in it so the amount of assistance to oil flow into the implement pump suction will be minimal.
    If it was fine when the weather was warm and now it isn't my bet is on the oil viscosity.
     
    Last edited: Nov 23, 2019
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  3. big ben

    big ben Senior Member

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    Pilot pump is air locked sounds like. Confirm by cracking the outlet line on the pump for a few seconds then tightening. It’s the pump closet to the hitch (small aluminum pilot/brake pump). Either the suction tubes or joiner hose or clamps are loose and sucking air. If that’s all good the pump is worn and needs replacement. And yes confirm it’s 10W hyd oil in the tank as mentioned above.
     
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  4. kshansen

    kshansen Senior Member

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    I would also be leaning towards a suction leak or too heavy of oil.

    A lot of time if a pump is sucking air it will sound like it's trying to pump marbles when cold.

    Might pay to put say 10 psi on the hydraulic tank and let it set for a while to see if anything starts dripping oil. Might take sometime with cold oil especially if it is heavier than 10Wt
     
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  5. rmllarue91

    rmllarue91 Senior Member

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    Very common on g's and h's there's big tube for suction line it's kinda hard to get with cab on if it's tighter than a crows foot two foot extension and breaker bar. I usually pull cab change all hoses redo suction line new pilot pump and replace or just remove falling down under cab insulation. Or just show operator the hose on right side above tank to loosen until it pulls prime.
     
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  6. Nige

    Nige Senior Member

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    Just a bit of clarification. Just because I said above that the specification of the breaker valve on the implement system is rated at 10psi doesn't mean you will get 10psi of pressure in the tank. Even hot the pressure may be way lower than that, and TBH it only needs a couple of psi to help the oil into the suction side of the pump provided the seals, joints, etc, in the suction lines are good and that the oil is the correct viscosity. The breaker valves are a service item BTW, should be replaced every 2-4000 hours depending on application. Your is probably original for the machine and long past due for replacement

    What happens if you run the machine all day then when you shut it down you (carefully) release the pressure in the hydraulic tank. Does it release any pressure at all..?
     
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  7. kshansen

    kshansen Senior Member

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    Yes, one of the G's at the quarry had a problem picking up it's prime when you did a hyd. oil change. Found that there was a quick connect for one of the pressure test ports under the right side platform that if you connected a hose to it with the other end open and let machine idle for a few seconds to vent a little air it would be good to go.

    Another G more or less stumbled on to a factory mistake several years after we got it. I was removing the steering and brake pump to fix a leaking mounting seal. Removed the cab for access and when I pulled the suction line off the bottom of the pump found that when installed at the factory someone had used the wrong seal.

    The suction line was machined for a standard o'ring but it had been installed using one of those "D" rings and the ring was smashed out all around the groove. Hard to believe they got lucky and it never caused a problem!
     
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  8. rmllarue91

    rmllarue91 Senior Member

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    That's it amazing oring face orings. Are very small 1/16 ? Maybe d ring maybe 5/16 ? I'd be surprised if a flange seal oring like a 4j-0520 wouldn't push out. a d ring blows my mind
     
  9. rmllarue91

    rmllarue91 Senior Member

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    Ks I had a 980h with a broken cab ground cause me to loose slot of hair in two days... It was intermittent. I know you have quite a bit of loader experience is that a common issue?
     
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  10. kshansen

    kshansen Senior Member

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    Well you made me do some checking and it was actually the suction line for the transmission pump on a 980GII machine. The correct seal should have been a 4J0527, so what ever "D" ring is close to that is what I found in there!

    This machine was new in the fall of 2002 and when I found and corrected the leak it was December of 2013!
     
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  11. kshansen

    kshansen Senior Member

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    Been retired for just short of 5 years but can not recall having that problem. But with the rubber mounted cabs if mounts were getting a little loose and the ground strap/wire was not installed so there was enough slack I could see that happening.

    As I recall when I did remove the cab from that 980GII the rubber mounting parts were a bit worn.

    A bit off topic but while reading my notes on that winter repair I saw that the "boots" around the control levers were bad and letting crap get in to the linkage for the hoist control valve. When I checked with Cat they were asking the outrageous price of $75.00 each for the little vinyl boots with a little piece of shoe lace to tighten them on the levers! Being the cheap SOB I am I mentioned it to the working group leader and he said give me one! He took it home to his wife who repairs seats on snowmobiles and she made a couple for free out of some scrap!

    Just for fun I looked on SIS just now and see they are now asking $79.05 each for those little bits of material! The crazy thing is the levers that the boot goes around are only $34.00!
     
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  12. JakeHarrington

    JakeHarrington Active Member

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    can anyone explain a bit more where the pilot pump is and what lines to try bleeding. I have never worked on a Cat this big so I'm not too familiar with the machine yet.

    I'm goin to try an experiment in a day or two and heat up the tank with one of those blower diesel heater to rule out to heavy of oil.

    once i identify the pilot pump i will check all the suction tubing goin to it from the tank.


    I hardly get any pressure at the breaker at anytime, hot or cold, on or off.
     
  13. Nige

    Nige Senior Member

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    You said it had 12k hours on it when it was bought. Have you ever changed the hydraulic oil & filters since you had the machine.?

    An oil & filter change would give you the chance to open up all the pump suction lines and replace the O-Rings in them while the tank is empty.

    Sound like you don’t have an Operation & Maintenance Manual. That probably ought to be on your shopping list. It’s less than $50 and you can download it from the internet.

    If you’re not getting any pressure from the tank at any time, replace the breaker valve as a first step. I gave you the number up above somewhere.

    One thing you never mentioned. Does it leak hydraulic oil from anywhere.?
     
  14. JakeHarrington

    JakeHarrington Active Member

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    i can't find any hydraulic leaks on the machine.

    i changed the hydraulic filter about 15 hours ago. it gave me a hard time getting the hydraulics to respond after swapping out that filter
     
  15. kshansen

    kshansen Senior Member

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    First question is do you know what oil is in the hydraulics?
    980H Pumps.jpg
    The number in the above picture point to the suction lines for the following pump:
    #1 is for the steering pump.
    #2 Is the transmission pump.
    #3 Is for the small gear pump that supplies oil to the brakes and the pilot system controls.
     
  16. Nige

    Nige Senior Member

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    If things went South after changing the filter, what brand was it.?

    TBH I’d still like to know what oil is in it.
     
    Last edited: Nov 24, 2019
  17. JakeHarrington

    JakeHarrington Active Member

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    I replaced it with a cat filter. I also have a baldwin on the shelf i can try.

    i topped it off with 5 gals komatsu AW46 that i had laying around. i know i used really use 10w hydraulic oil but i didn't have any on hand.
     
  18. JakeHarrington

    JakeHarrington Active Member

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    Also if this is any help the brake warning light. always turns on when i start the machine for like a minute.
    I'm guessing its a low pressure code and I'm also guessing it has something to do with my issues after reading that the pilot pump runs the brakes
     
  19. Nige

    Nige Senior Member

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    Stick with the Cat filter for now. I was more concerned that you had used a parts store brand X or similar.
    No it's not. It's the time it takes the brake accumulator to charge up when you start from cold (it will leak down while the machine is parked overnight). If the light goes off within a minute of so of a cold start it sounds like your brake pump is in reasonable shape. And guess what, that's the same pump that runs the pilot system. Now if you had a manual all this, and much more besides, is explained in it. Do you see a recurring theme here..? (see post #13 above)
     
  20. kshansen

    kshansen Senior Member

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    One thing I'm not understanding is this comment from the first post:
    It sounds like it sucking air almost but i can't find any leaks.

    By saying "sounds" do you mean to say it is making some kind of noise?