“O” rings used on Mid fifties OMC

[billy-j]

Hello. I have been asking other outboard enthusiasts and have been unsuccessful in getting a clear answer to a question. My question only applies to 1954 to 1958 OMC engines. Johnson and Evinrude. 5 1/2 to 35 horse engines. Are the rubber “o” rings used in these engines a standard size or did OMC make them a little different dimension as to make them ( proprietary ) so you have to buy ” o” rings from them to be guaranteed a correct fit ? I am talking about crank seal, shift shaft, lower unit , drive shaft spline where it fits into crank shaft etc. I have been buying the ” o” rings from my OMC parts supplier using the original pat numbers and have had no problems but they are a couple of dollars each. I do not mind spending the money but when you have a lot of engines to do the cost adds up quickly.I know the fuel connector “o” rings are a weird size but what about all the others? Thank You Bill,

[labrador-guy]

billy-j all I can tell you is what I do! I have three assortments of O rings that I bought at harbor freight. Metric and USE a couple other draws of o rings that came in gasket sets that I have saved over the years. Sometimes I still can’t find the size that I need. I have an ACE hardware close to me that usually will find what I want. OE parts are very expensive and when ya put on some shipping charges I can’t stand paying 20 bucks for a 10 cent part! Yes those o rings that go in the fuel connectors might be the exception.

dale

[bobw]

I’m with Dale on this. I can usually find a correct O-ring at my local Ace Hardware that carries a huge assortment of pieces. Here’s a couple reference tables I often use to find the corret size. If you have the original OMC part number, you can find it here and either buy a Sierra or GLM equivalent O-ring or use the listed dimensions to find one at a hardware store.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

• This reply was modified 3 years ago by Mumbles.

2 users thanked author for this post.

billy-j, Rusted Junk

[frankr]

O-rings are commercially sold as “dash” numbers. With perhaps an exception or two, OMC used standard sizes. 70 Durometer, Buna Nitrile. Cost= pennies each

https://www.mcmaster.com/o-rings/oil-resistant-buna-n-o-rings-8/

• This reply was modified 3 years ago by frankr.

1 user thanked author for this post.

billy-j

[billy-j]

What does GLM stand for on the 2nd. “O” ring chart from the earlier post from bobw?

[bobw]

GLM is GLM Marine Products. Lots of aftermarket parts for both vintage and modern day outboards.

https://glmmarine.com/

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[joecb]

Of all the O rings on OMC that seem to cause a problem in correct fitting are the small ones used in the twin-hose pressure tank fuel connector. There have been several proposed standard replacements for the originals, some seem too skinny some too fat. I’m not sure where we are on this one, at this point in time.

Joe B

[outboardnut]

Boy talk about a sore subject with me.
I got sick and tried of paying high prices for O-rings
So I have been finding alternative places to buy them.
I used the size chart listed above
Quad rings-A fellow member gave me enough for a life time
drive shaft seal (upper) 339543- Tractor Supply or I believe Dan in TN bought a bag of 100
shift lever o-ring 303191-ace hardware
surrounds bottom crank bearing 302537-I bought a bag of 100 and have been selling on Ebay-If you want some contact me via private message
https://www.ebay.com/itm/294614912270

[Buccaneer]

I bought a “buna” o-ring kit online a couple of years ago, for around $20,
and it’s saved me quite a few times. Every once in a while though,
I’m lacking in finding one just the right size or thickness.

Prepare to be boarded!

[Geer Pyron]

I buy cord stock from Grainger and make my own.
Innapinch.
Cut the ends square!!
G

JMGP

[Author]

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