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Cat 235 hydaulic swivel again...

Discussion in 'Excavators' started by cheddarbob56, Aug 4, 2014.

  1. cheddarbob56

    cheddarbob56 Well-Known Member

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    Guys - I posted a while back about my hydraulic swivel leaking in our Cat 235 excavator. With help from you guys here we put new seals in it and hoped it didn't need re-chromed(from the pictures I posted a few guys thought it didn't look to bad, and I as well thought it looked fine). Put it all back together and still leaked. We had jobs to do so we thought we better just hang a bucket underneath to catch the oil and get our jobs done and keep the oil full. Well it actually almost stopped leaking for a few days just to where it would drip a little here and there. We got done with things and it's been sitting for about 3 weeks now and went to use it this weekend at my place digging some holes and it was really leaking a lot again. Worse than before even I think. Any ideas what's going on? Do I need to get a rebuilt... send it off to get re-chromed? Something else going on that's blowing seals out? Also we went to top the oil off after running in an hour or so and there was pressure in the hydraulic tank... is this normal? I didn't think it should be pressurized at all... when I loosen the oil fill cap it would exhaust a lot of air and some oil residue out the breather hole in the cap. I need some advice.

    Thanks guys.

    Chris
     
  2. Nige

    Nige Senior Member

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    To set your mind at rest about the tank. It is designed to pressurize when the oil gets hot to assist the suction of the implement pump(s). You should be very careful loosening the cap when the oil is hot, you could get a face full of hot hydraulic oil.

    I was one of those who didn't think it looked bad enough to require re-chroming when it was torn down the first time. However it's sometimes difficult to judge from a photo, maybe it does need it.
     
  3. cheddarbob56

    cheddarbob56 Well-Known Member

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    OK that's good to know. I'm glad to hear that it is designed that way... and yes I haven't taken the lid off with it hot just started to loosen it and noticed it was pressurized so I quit.

    I remember that, but I thought the same thing, it sure looked fine to me too. Is there any other issues that could be causing it to blow seals or is it just that it needs rechromed? We are fine doing that as long as we are pretty sure that is the problem.

    Thanks.
    Chris
     
  4. big ben

    big ben Senior Member

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    I have never worked on a 200 series Cat but I assume a swivel is the same on them. You definitely have to look close the second time. Carefully take it apart to see which seals are blown and what they are for. I would check pressures for the travel, and case drain. It strange the leak would come and go.....Maybe you damaged a seal on reassembly. Could be several reasons for the leak.
     
  5. overworked

    overworked Senior Member

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    I have done quite a few , make sure you don't have a leaking oring on one of the pipes on top, the tank uses manifold pressure from the engine to pressurize it. Best to open when cold or when running. SLOWLY, when you hear a hiss, stop opening and wait till it stops or it will siphon the oil.
     
  6. cheddarbob56

    cheddarbob56 Well-Known Member

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    I got back to working on the excavator again this weekend. Put both new hydraulic filters in and still have a terrible leak from the top of the swivel. The oil seems to be coming out of the front and rear of the unit just under the big center plate that it bolts to. I was pretty sure I needed a new rotor. I found a place that re-chromes them and can have me one in a couple weeks however he wanted a number off the rotor which I didn't have because I don't have the swivel off the unit yet. I took the bottom plate off of the swivel because the company thought there might be a number there but there wasn't, anyways with the machine not running (haven't started it since Sunday afternoon) it drained off about 15-20 gallons of oil. When I took the bottom cap off it was running quite a bit of oil out of the center of the spool. Is this normal to have that much oil without even running the machine in the last 24 hours? Or do I have something else going on. Just want to make double sure that it is the swivel spool before we spend for a new one. Thanks guys.

    Chris
     
  7. Bob/Ont

    Bob/Ont Senior Member

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    The only way to stop the hyd oil from dribbling out all the time is to separate and cap the case drain line from the swivel to the filter, let pressure out of tank first. Those swivel cores always need chroming, dirt gets in the top and wears the core at the top seal area.
    Later Bob
     
  8. cheddarbob56

    cheddarbob56 Well-Known Member

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    Alrighty. Thanks Bob. We will be getting it re-chromed and re-sealed. Thanks for everyone's help on here.

    Chris
     
  9. cheddarbob56

    cheddarbob56 Well-Known Member

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    Quick question on this again guys. We have parts on order, have a re-chromed rotor spool on it's way. What I'm wondering is if I should take the housing to get a little bit taken off the face so that it's a nice smooth surface. Apparently they updated the spool to have an inner and outer lip seal to keep dirt out better, my housing already had the internal lip seal but it sounds like the new rotor spool we are getting will have the external lip seal also. So if this is the case I'm guessing that I would want a nice smooth surface for it to ride on correct? Will it hurt to take a few thousandths off the face of the housing? I'm guessing we can't take much off or the seal won't contact the face at all correct? Or do I just leave it as is. Here's a picture to show what it looks like.

    swivel housing.jpg swivel housing_2.jpg

    Edit to get pictures out of body of text.
     
  10. Nige

    Nige Senior Member

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    A little touch up to give a smoother surface would not go amiss. The trade-off is removing as little thickness as possible while still achieving the correct surface texture.
     
  11. overworked

    overworked Senior Member

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    I would not take anything off that surface, those marks are from dirt getting between that housing and square top piece, if you have it machined you will only make the gap larger for more dirt to get in there, nothing seals on the face.
     
  12. cheddarbob56

    cheddarbob56 Well-Known Member

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    Am I looking at this right when I look at this update that it should have a little smooth area for the seal of the inner spool to ride on?

    housing.JPG
     
  13. overworked

    overworked Senior Member

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    Now in that picture , I would say yes, that's the update, new seal added.
     
  14. Nige

    Nige Senior Member

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    If you don't smooth that top surface off, at least where the seal rides, you're going to tear the new seal to pieces PDQ.
    If you have access to a machine shop that can do metal spraying the surface could be built up with arc spray and machined back to original size.
     
  15. castirondude

    castirondude Member

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    Reading old threads here. I also have a Cat 235 and so far it has not leaked from this spot. Is there a preventive measure I can take to prevent dirt from getting in this seal? Like pressure washing/etc.
     
  16. Nige

    Nige Senior Member

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    Keeping it clean isn't going to hurt any. Dirt + oil always makes an extremely good grinding compound which is no problem until you have the slightest oil leak and it turns into something extremely abrasive.