CRANKCASE OIL SEALS

[dwhitford]

Who has crankcase oil seals for the Mark-20H and Mark-25?

The original Merc part number for the top seal is 26-20530. Bottom seal number is 26-20948. The top seal has a slightly bigger ID to fit around a 0.935'' crank journal, bottom seaI for a 0.870'' crank journal.

[champhotrod]

You can use a SKF 9243 for the top crank seal.

Cooper Jess

[dwhitford]

Thanks, Cooper, for the good info. -- dave

[ZUL8TR]

I find Google search with part numbers usually works

Here are some jobbers with the top and bottom seal, different prices, check ship rates for best total $

Bottom
http://stores.outboardparadise.com/seal-26-20948/

Top
http://stores.outboardparadise.com/s...rank-mk25-20h/


Bottom
https://www.vintageoutboard.com/prod...kshaft-mark-20

Top
https://www.vintageoutboard.com/search?q=26-20530


Also try David at

http://www.aeroliner-boats.com/11.html

[dwhitford]

Thanks for the good leads. -- dave

[rumleyfips]

Dave : Goggling oil seal 9243 and 8624 will show lots of places to buy including ebay and amazon.
If you google ' .875x1.250x.188' the seal number and availability will pop up. Shopping without having to put your pants on.

[dwhitford]

Thanks, John . . . more good info! -- dave

[rumleyfips]

I should have mentioned: googling the dimentions ( inch or metric ) of a bearing will bring up the number.

[Smitty]

The original bottom seal might have had a hole drilled in the steel ring. This was a common feature in factory engines in pre-emissions years, for the purpose of draining off any build-up of excess oil in the 'case when trolling or idling for long periods. In later, more pollution-conscious years, this feature was eliminated, and excess oil was recirculated in various ways (sometimes causing engines not to troll as smoothly as the earlier models). Anyway, the holey crank seal is not a very desirable feature in a race motor, so look for an undrilled lower seal. (Gads, this is an ancient memory!). I don't have numbers, but you can always take measurements with you to your bearing/seal supplier.