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Bobcat 753 no steering

Discussion in 'Skid Steers' started by birchwood, Mar 18, 2017.

  1. birchwood

    birchwood Member

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    Hey guys I am new to the forum and new to skid steers, I recently purchased a 753 with problems It will not steer to the left or right. Forward and Reverse seems to be good but when you try to turn it acts as though it wants to turn but will not. I have replaced a leaking drive motor hose and I replaced the control valve seals for the bucket I purchased the case drain filters and plan on checking them tomorrow. This machine has been neglected and is in need of alot of attention. I just dont know where to start with this steering problem. Any help and suggestions will be greatly appreciated.
     
  2. willie59

    willie59 Super Moderator

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    No where near getting to a solution for your problem, but some more questions to help with figuring it out. 1), seems to go fwd/rev fine, well, how much power does it have when you drive straight into a pile of material? Does it push the material or does the drive stall out? 2) does the bucket lift just fine with a full load of material?
     
  3. colson04

    colson04 Well-Known Member

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    Have you checked the linkages under the seat? Our 753 had a spring loaded bolt break on the return to center plate. This caused the plate to vibrate out of position. Without that plate, both sticks wanted to move together and made the machine erratic to drive. We got lucky and all that of the parts were found in the machine, just had to replace that special bolt.
     
  4. birchwood

    birchwood Member

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    I was able to run into a pile gravel and did seem to lack power. I was able to get about a third of a bucket of gravel and the bucket traveled slow thats when i found the control valve seals were leaking. I just finished replacing them so I havent had a chance to check out anything yet I was planning on checking case drain filters today and servicing the engine. I know the middle control valve or top valve seals were really deterioated the one that is controlled by the right pedal.
     
  5. crewchief888

    crewchief888 Senior Member

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    i'd check the drive belt, it's probably loose..


    :eek:
     
  6. willie59

    willie59 Super Moderator

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    My thoughts as well crewchief, I'd check that before I went into the case drain filters
     
  7. birchwood

    birchwood Member

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    I just signed on so I will check the drive belt tomorrow, but I did get everything together today. The case drain filters I did check and someone has removed the bronze filters out of both so I will have to get some springs next week because I have already purchased the bronze filters. I filled it with Hydraulic fluid and let it idle for awhile to purge the air and fill the hydro lines I still had no steering, I wanted to take the bucket off because the pins were seized up finally got the bucket to release and now it will turn with the right stick but only tries with the left stick if you play with it you can inch it around. With the right stick it will turn forward and reverse with the left it just barley moves. If I put the bucket on it just barely moves right and left wont move very good. I will check the belt tomorrow and report back.
    Thanks for the responses
    cause Im a lost ball in high weeds with this thing.
     
  8. birchwood

    birchwood Member

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    I know this may be a dumb question Where is the drive belt?
     
  9. willie59

    willie59 Super Moderator

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    Not a dumb question. If you're new to Bobcat machines the only way you're going to understand them is ask questions. The drive belt connects the engine flywheel to the drive/work pumps. The belt has a spring loaded tensioner to keep proper tension on the belt, and it's rather tight tension. The machine would originally have had a rather large plastic cover over the flywheel housing. If it's still there you need to remove that cover to get a clean view of the drive belt.
     
  10. birchwood

    birchwood Member

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    I found and tried to adjust the drive belt today according to the decal on the back door there should be a pointer that should be pointing at 3:00 when properly adjusted, but I cant see a pointer, I tried to tighten but I think its in the same position as before, I am not sure how tight it should be but the belt is cracked and probably be replaced so I will pick up a new one and try again this week.
    Thanks again for the responses
    I am sure I will have more questions
     
  11. willie59

    willie59 Super Moderator

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    It's not unusual for the sheet metal plate that has the pointer to come loose over the years which causes the pointer plate to simply spin around on the shaft, no longer points to 12 to 3 o'clock positions. One can still tension the belt with the pointer messed up, but it helps to have some experience with doing that. The belt tensioner is spring loaded when it has the belt under tension and it takes a good amount of prying pressure pushing down on the tensioner mounting plate to crank the tensioner around on its nautilus cam to load the belt. Basically what you have to do it crank down on the tensioner mounting plate until the tensioner idler bottoms out on the internal nautilus cam, then let it back off just a tad bit.
     
  12. crewchief888

    crewchief888 Senior Member

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    since you alrady know the drive belt ist in the best condition, i'd recommend replacing the tensioner assy while you are there.
    many time those old worn out tensioners just wont move. and on older the machine the pulley is usually worn, and the bearings are loose


    :eek:
     
  13. birchwood

    birchwood Member

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    hey guys I"m back, well my new belt came in and I picked up a couple of torsion bushings for the steering arms because they were very loose. I installed the new belt, still could not find the pointer I got it as tight as possible, it seems pretty tight. I installed the bushings someone had installed aluminum spacers instead of the correct bushings, I still have no steering with the bucket on with bucket off it will steer to the left and right and try's to back up with the left stick but not much there. I did notice its slow going up a grade and if pointing down hill it doesn't want to turn. I loaded a bucket of gravel the lift worked and forward and reverse worked but no steering, drop the bucket off and on level ground it turns. you do have to run the rpm's up about 1/2 to 3/4 to get it to turn. I'm open to any ideas at this point. Another thing I just found out, the boss system has been impossible to see outside but when I brought it inside the shop I could see it displays a HP 3 code and looks like a gear or tire with 2 arrows pointing at it was flashing according to the boss HP 3 means the hydraulic pressure sensor is disconnected but I have no idea on the flashing symbol.
     
  14. crewchief888

    crewchief888 Senior Member

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    you're running at less than 1/2 throttle?
    bobcats are designed to be at full throttle all the time...
    it's possible the sender is disconnected, it should be in the engine compartment on the RH side around the hyd oil filter.
    if you disconnect the harness plug and it has oil in it, replace the sender the fault should go away. if not, the fitting that the sender screws into is a filtered "snubber" it may have some crap in it, ive drilled ou the internal filter and faults have gone away. if not, the last thing that may be going on is you have low charge pressure. install a guage in that posrt and check the charge pressure. i believe on that model warm (130 degree oil temp) charge pressure should be in the 150PSI range, but dont take my word for it, get the spec from your dealer.


    :eek:
     
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  15. birchwood

    birchwood Member

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    OK I am back I had to find a gauge to check pressure, dealer said the book says 200 psi at 128 degree operating temp. ( he mentioned he thought that was a little high) I checked at idle after warm up it was about 80 psi and at full throttle it was about 130 psi. I had to order a new pressure switch they were out of stock, may be in friday but I doubt it. I ran the machine at full throttle and it responded a little faster but left handle is still weak moving forward and barely moves in reverse, also with left handle at reverse and the right forward it groans loud like its not getting fluid. and thats with the bucket off, with the bucket on its worse. One of the mechanics suggested checking the replenishing and relief valve on the pump, do you have to remove the pump for that? I am going to keep after it till I find the solution I was just hoping it would be a fast cheap fix. That's not looking to promising at this point.
    Thanks again for the help
    I really need it,
     
  16. crewchief888

    crewchief888 Senior Member

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    spec is 200 psi, and you have 130psi, you're loosing charge pressure somewhere.
    you can remove the hoses from the hydrostatic pump, cap off the fittings on the pump, and recheck your charge pressure.
    reconnect the hoses, then do the same to the other side. see what happens to the charge pressure during both tests.
    if one side is a lot higher than the other, the (low side) motor is probably leaking internally.


    :eek:
     
  17. birchwood

    birchwood Member

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    sorry I have taken so long to get back I have been trying to find some caps to put on the pump, yesterday I went to the hydraulic store and told them what I was doing and they gave me 1 inch caps I told them I thought they were to big and opted to buy 3/4. Well as my luck goes they were to small so I went back today and purchased 1 inch and they are to big so now I have to try again tomorrow. And yesterday I forgot to tighten the hose back and came in today to hydraulic fluid all over the shop floor. Maybe I will just try the bobcat dealer. But I am trying, I will get back as soon as I can get this pump tested.
     
  18. willie59

    willie59 Super Moderator

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    Are you trying to fit pipe thread caps to those fittings? If yes, the put outlet lines to the motors should have JIC fittings, not NPT, I'm thinking maybe -12 JIC. If a 1 1/4" wrench fits the hose fittings it's a -12 JIC cap for the fitting.
     
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  19. birchwood

    birchwood Member

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    Thanks willie, I think your right on the threads but im using a 1 3/8 service wrench on the fitting. but I checked the invoice where I bought the hose and there is a lot of JC-12 in the description, but he did add a adapter to the end because he didnt have the correct crimp on fitting but I think it is a -12 JIC. I will carry this invoice with me and make sure this time.
     
  20. willie59

    willie59 Super Moderator

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    Could be one of two things being an 1 3/8 hex size, could be an oversize hex, I've seen it before, or it could be a -14 JIC, don't see them that often. But I'm quite certain that should be a JIC fitting on the outlet lines of the drive pump for the hoses going to the drive motors. -16 JIC takes a 1 1/2" wrench to fit the fitting hex.