Johnson V6 O-ring dual uses???

[bob johnson]

So i bought some seals for my lower unit along with the water pumps...figured Id try to replace as much wear items as i could .( with out a total rebuild) so im replacing the seals for the driveshaft, and the seal for the prop shaft and the seal for the shift rod, and last night i took the carrier out of the LU and see 2 large O-Rings....one on each end...and thought...heck i should replace them, but now the weekend is here...no time to order parts. the local guy doesnt have them in stock. so im looking at sierra parts # and it shows an O-Ring that also is used as the Cylinder head seal!.... i saw this on a third site as well..... is that right?? the parts diagram actually has a seperate part # for each O-Ring.... but the Sierra and several other aftermarket parts houses show the same part # for both the seal in the Lower Unit and the seal around the combustion chamber in the head....... I think i can go find the sierra locally... plus I think i have some O-Rings for my other motor rebuild project..but they are home and Im looking to stop and check for availability on the way home in a few minutes

 

[bob johnson]

by the way the sierra # is 18-7133-9 the brp # is 0305123......or sometimes they leave the first 0 off and just call it 305123. the cylinder head O-Ring listed on the BRP site is 0335523...

 

[jakedaawg]

Once you get the two new parts from bro use a caliper and let us know if they are truly the same dimension ...an o ring is an o ring.

 

[Scott Danforth]

may be one is EPDM or NBR and the other is viton or another flouroelastomer. you can have 6 different o-rings with the identical dimensions, and each one has a different purpose based on its material.

 

[bob johnson]

i ordered the specific o-rings for the lower unit, but at home i have a rebuild kit for a 60 degree looper V4....which uses the same O-rings on the head as the V6's..... and i compared the O-ring that came off the lower unit and the one in the rebuild kit for the head.... they are different..... they may be the same ID OR OD, not sure, but the thickness is muich different.... the head o-ring is a smaller cross section, the lower unit O-ring is THICKER........so im still waiting on the right parts....sooo dont always believe cross referencing!