450 Pump O-Rings

MeanGene1 · Sep 5, 2010

My "new" 450 gas was leaking at the flange between the live pump and the steel hyd lines, so I pulled it apart this morning, the o-rings seemed in good shape, replaced them with standard o-rings which matched what came out. Still leaks just as bad, definitely leaking out between the flanges, not a cracked line, Are they standard o-rings, or a special size or type? I've run into quad rings and such before, and the flanges seemed in good shape and flat, seems like it should be sealing up if the rings are correct. I haven't found any kits for this application, does it just use standard rings? Hate to take it apart again to straightedge it, it's a booger to get lined back up with the solid steel lines

CNKS · Sep 5, 2010

Get the part# off www.caseih.com and get them from the dealer, will cost 5X what they are worth, but will be correct. Matching orings without a number is sometimes difficult. The ones in there when you bought it could be wrong also.

MeanGene1 · Sep 5, 2010

Thanks, but you're telling me what I already know, not what I asked LOL. The ones that came out may be the wrong ones that someone else installed at some point, and they are standard size rings, matching the ones in my o-ring kit. Does anyone know if the standard size ring is correct, or does it call for a special size? They don't protrude below the surface much, but their inner diameter fits in the groove snugly, a slightly larger cross-section ring would probably cure it- it didn't leak after the switch until the oil got warm. If there is such a ring, I'd like to try it before resorting to pulling off the steel lines and truing the flange surface on the Bridgeport, flushing the lines, etc. Didn't want to buy overpriced dealership rings and then find out they're the same ones that are in my kit

CNKS · Sep 6, 2010

My answer is the same -- get the IH rings, they don't cost that much -- before you start trying to modify things. The orings are the wear part, not the grooves. Or try one size up in size -- that never has worked for me. The parts book sometimes gives the ring dimensions, sometimes not, you can look that up.

Janicholson · Sep 6, 2010

The IH rings (as Below) or take the old rings to a good hydraulic shop, or Motion industries/Grangers and get slightly thicker rings. Teflon based rings are tough. Jim

MeanGene1 · Sep 6, 2010

Thanks again, but really, that's not what I asked- if anybody knows if they're non-standard rings. Checking and trueing a flange if necessary on the Bridgeport isn't exactly "trying to modify" a part. Never mentioned any problem with the grooves, not sure where that came from. The old and replacement rings fit the ID of the groove correctly, larger ring will not fit the OD, and I agree, that solution rarely works. Of course I could "look it up", but with the number of these tractors/pumps out there, I would assume that someone would know from actual experience, and not mind sharing their knowledge, which would save me a lot of running around and /or ordering parts that might not solve the problem. There are a couple good hyd shops in town, neither of which are open this weekend, a larger cross-section ring should indeed fix it if the flanges are true
Wish I still had that huge box of leftover o-rings and quad rings I gave to the young CAT mechanic a few years ago LOL

Janicholson · Sep 6, 2010

I believe they are non standard rings. Jim

MeanGene1 · Sep 6, 2010

Thanks, Jim, makes sense as they don't seem to protrude below the surface as much as they should to seal correctly. As the ones that came out are identical to the plain 'ol generic rings in my kit, seems like someone installed incorrect "standard" rings in the past, now I know for sure what needs to be done.
Thanks again for sharing your knowledge and experience, saved me a lot of running around & "looking up"

Janicholson · Sep 6, 2010

Orings and grooves need to be able to compress ~1/4 of their section diameter to seal correctly.
This provides contact on 4 surfaces but not quite groove filling. If they aren't fat enough they will expand outward and collapse inward every pressure cycle and leak. (see Challenger disaster) Jim

MeanGene1 · Sep 6, 2010

Yep-that's what made me suspicious, as the rings were barely below the flange surface, didn't look like enough to seal correctly. Looks like someone just popped in a set of standards in the past- I need some with a larger non-standard cross-section, as apparently was used originally. Seems funny, all the places that list new pumps for sale, and I've never seen the o-rings needed for the installation listed?

IH fan · Sep 6, 2010

Go to a hydraulic repair place and ask for [u:2797be3fc7]"JIC" O-rings[/u:2797be3fc7]. They should have a [u:2797be3fc7]yellow dot[/u:2797be3fc7] on them to indicate their cross-section and hardness. without seeing the fittings, I wouldn't know what size to ask for, but most gear pumps I have seen on tractors have -8, -10 or -12 JIC fittings on the pressure side.... usually -12 or -16 on the suction (inlet) side.

450 Pump O-Rings

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