How close is "close enough" for hydraulic O-rings?

[gw@swmo]

I just received a new Boss 27-ton log splitter from Costco. When Costco assembled my unit, they left out a rubber O-ring where a hydraulic hose attaches to the oil reservoir. Costco is trying to contact Boss to obtain a replacement, but they are not answering their phone. The email I sent to Boss was returned as undeliverable, and for the past two days, I can't get their webpage to load. So I may need to get the O-ring elsewhere.

The missing O-ring is described as 15mm x 1.9; it's outer diameter is 15mm and the rubber material is 1.9mm in cross section, so the inner diameter is 11.2mm. So far, I have not been able to locate this exact size online from any US source. But there are plenty of online sources selling nitrile O-rings which are 15mm OD x 11mm ID x 2.0mm cross section. Is it unrealistic to think the extra 0.1mm in cross section might still work?

There is another souce in the US selling an O-ring with the correct 1.9mm cross section, but ID of 11mm and therefore OD of 14.8mm. So the O-ring would have to stretch 0.2mm in diameter. Close enough, or not?

I have found a source of the correct size from Hong Kong, so maybe that is my best option?

 

[salecker]

Find a Oring kit from locktite and make your own

 

[gw@swmo]

Find a Oring kit from locktite and make your own

Thanks for the suggestion. That O-ring kit looks like an interesting idea which might be really helpful in some situations.

However, the smallest cross section rubber in the kit is 3/32" which I believe converts to 2.4mm, where I need 1.9mm. I think I might be able to fudge a little bit on the diameter of the O-ring, but I'd like to keep the cross section as close to specifications as possible.

 

[Pinesmoke]

For a no pressure connection it should be fine, I assume it's the return line to the tank. If you are running normal hyd oil there is no need for nitrile, buna will be good.

Poke around, I would think there will be a hydraulic store close to you. You can check McMaster.com if all else fails, they have anything you could need.

WARNING
Mcmaster-carr is a black hole of aallllll kinds of goodies and can suck you in. 😂

 

[gw@swmo]

For a no pressure connection it should be fine, I assume it's the return line to the tank. If you are running normal hyd oil there is no need for nitrile, buna will be good.

Poke around, I would think there will be a hydraulic store close to you. You can check McMaster.com if all else fails, they have anything you could need.

WARNING
Mcmaster-carr is a black hole of aallllll kinds of goodies and can suck you in. 😂

The fitting is of the O-Ring Face Seal type, and it is for a hose described as the "oil return hose."

No doubt, McMaster-Carr is an awesome resource! So when I discovered they do not carry the exact size I need, I knew I was looking for something out of the ordinary.

McMaster-Carr does have several offerings with 15mm OD, but with a cross section of 2.0mm. I'm guessing that's close enough to 1.9mm, but I don't really know, which is why I'm asking.

Thanks for the tip about looking for a hydraulic store. I found two in my home town which I will try to contact tomorrow.

 

[Turbo89]

The fitting is of the O-Ring Face Seal type, and it is for a hose described as the "oil return hose."

No doubt, McMaster-Carr is an awesome resource! So when I discovered they do not carry the exact size I need, I knew I was looking for something out of the ordinary.

McMaster-Carr does have several offerings with 15mm OD, but with a cross section of 2.0mm. I'm guessing that's close enough to 1.9mm, but I don't really know, which is why I'm asking.

Thanks for the tip about looking for a hydraulic store. I found two in my home town which I will try to contact tomorrow.

If you know the fitting p/n, the Parker fitting manual has really good guidance on o-ring fits.

Generally speaking, bigger is better… it it’s too big it’ll get cut at assembly. Since it’s a face seal, that small of difference probably won’t be noticeable. Put some o-ring lube on it at assembly, if you don’t have any use oil or Vaseline.

If you post up the fitting p/ns and manufacturers, I’ll dig through my old Parker books and see if I can find the allowable o-ring tolerances, next week when I’m back in the office.

 

[Pinesmoke]

A face seal fitting on the return you are good. I would give it a try it should be fine.

 

[brenndatomu]

McMaster-Carr does have several offerings with 15mm OD, but with a cross section of 2.0mm. I'm guessing that's close enough to 1.9mm

Yup, that'll work fine...send it!

 

[gw@swmo]

If you post up the fitting p/ns and manufacturers, I’ll dig through my old Parker books and see if I can find the allowable o-ring tolerances, next week when I’m back in the office.

Thanks for the offer, but I don't see any markings on it, and the log splitter parts diagram does not even show it. Not sure it's replaceable -- looks like it might be welded in?

I have high hopes that I can find an o-ring in the more common size (2mm cross section) somewhere in my home town, population 170k. So if I'm successful, I will know soon enough!

 

[John Mc]

If you are running normal hyd oil there is no need for nitrile, buna will be good.

Nitrile and Buna-N are two different names for the same thing. Perhaps you were thinking of Viton?

 

[Pinesmoke]

Yes, blew right past that.

 

[Whitenuckler]

Thanks for the offer, but I don't see any markings on it, and the log splitter parts diagram does not even show it. Not sure it's replaceable -- looks like it might be welded in?

I have high hopes that I can find an o-ring in the more common size (2mm cross section) somewhere in my home town, population 170k. So if I'm successful, I will know soon enough!

View attachment 339762

I would guess if it's a return, then as long as it fits in the rabbit or slot, and is thick enough to be proud, then it should work. If it were on the high pressure side it probably would not be that type anyway.

 

[gw@swmo]

After striking out at the auto parts store, a pretty good hardware store, and an industrial supply house, and I finally found a 15mm x 2.0mm O-ring at a hydraulic specialty store. I was treated like the nuisance customer that I was, but they delivered. They said it was too much trouble to take my money, so it was free. Not wanting to push my luck by looking a gift horse in the mouth, I was afraid to ask if their O-ring is oil-resistant, but being a hydraulic specialty store, I assume they would not stock anything else?

Too late in the day to install it now, so it will be tomorrow before I can try it out.

 

[salecker]

I would guess if it's a return, then as long as it fits in the rabbit or slot, and is thick enough to be proud, then it should work. If it were on the high pressure side it probably would not be that type anyway.

That type is used for high preasure
My Hitachi EX200 has them on the lift cylinder lines, probably more. I just changed one line this spring so i know for sure that one is like it.
Same as the lines on my 426 Cat backhoe

 

[gw@swmo]

Yeah! Today I filled the hydraulic tank, fired it up to prime the system, and no leaks!

I am a little confused about the hydraulic tank fill level. The manufacturer's instructions for checking the oil level say to "push the dipstick all the way in" -- does that mean I should screw the filler cap down all the way, then unscrew it to check the oil? Or should the filler cap be resting on the top of the threads (not screwed in) when I take a reading?

 

[Whitenuckler]

Yeah! Today I filled the hydraulic tank, fired it up to prime the system, and no leaks!

I am a little confused about the hydraulic tank fill level. The manufacturer's instructions for checking the oil level say to "push the dipstick all the way in" -- does that mean I should screw the filler cap down all the way, then unscrew it to check the oil? Or should the filler cap be resting on the top of the threads (not screwed in) when I take a reading?

[td width="561.044px"]Oil Capacity[/td]

[td]

3.5 gal​

[/td]​

If you put 3.5 gallons in, then try it each way. I know what you mean though. My lawn mower with a honda engine is just touching, but my snowblower is treaded in, or maybe the other way around. I wish they has never changed it. It was always threaded in before.

 

[gw@swmo]

@Whitenuckler, so true. The Kawasaki engine on my John Deere mower says to check the dipstick without screwing it in.

The owner's manual for my Boss log splitter says I should put in 3.5 gallons, prime the system, then check the level again. First problem, I had with those intstructions was, the oil started overflowing the fill spout before all of the 3.5 gallon was in. I was measuring the oil with a half-gallon container. After putting in 3 gallons, I had just started to pour in the final one-half gallon when it started to overflow. After priming the system, it took the remainder of the final half-gallon plus about another quart.

Right now, the dipstick shows I have the correct level if I take a reading with the hydraulic cap/dipstick screwed all the way in. But if I take a reading without screwing the cap down, the level is too low. The instructions warn about not over filling, so I am half-afraid to add any more until I understand how the dipstick is supposed to work. The drawing in the manual looks like they are showing the filler cap screwed down when illustrating the correct fill level, but it seems like the instructions should say so, if that is the approved method.

 

[Jags]

That half inch difference between the two methods probably will not make a nickel's worth of difference. The difference of a quart in a 3 1/2 gallon simple hydraulic system is miniscule

 

[brenndatomu]

Basically as full as it can be and not barf out the vent when hot... oil level in a engine is more critical

 

[Whitenuckler]

@Whitenuckler, so true. The Kawasaki engine on my John Deere mower says to check the dipstick without screwing it in.

The owner's manual for my Boss log splitter says I should put in 3.5 gallons, prime the system, then check the level again. First problem, I had with those intstructions was, the oil started overflowing the fill spout before all of the 3.5 gallon was in. I was measuring the oil with a half-gallon container. After putting in 3 gallons, I had just started to pour in the final one-half gallon when it started to overflow. After priming the system, it took the remainder of the final half-gallon plus about another quart.

Right now, the dipstick shows I have the correct level if I take a reading with the hydraulic cap/dipstick screwed all the way in. But if I take a reading without screwing the cap down, the level is too low. The instructions warn about not over filling, so I am half-afraid to add any more until I understand how the dipstick is supposed to work. The drawing in the manual looks like they are showing the filler cap screwed down when illustrating the correct fill level, but it seems like the instructions should say so, if that is the approved method.

View attachment 339771

Yes, that make sense as the system has no oil in it when new. I'd go with what you used, minus any spillage. When they say not to thread in the dipstick, they would usually be very specific, and sometimes emboss the dipstick. As long as you are close you should be OK.
It shows in screwed down like you say, and the you have a min max.

Hey how does it work?

 

[gw@swmo]

Hey how does it work?

It works pretty good. I started out working on some rounds of ash, hackberry, elm, and sycamore that I cross cut a couple of months ago. Some of the twisty-grain sycamore was a struggle, but the rest split OK.

It was hot today -- I quit about noon when the temp hit 90F. I did notice maybe 6 or 8 ounces of hydraulic fluid came out of the fill spout, so now I know to cut back a little on the oil fill.

 

[Turbo89]

Nice size splits, just the way I like em! It was f’n hot today, I’m waiting for some cooler weather to get back at it.