Info provided by Jerrytex.

This is a list of o-rings for a 912 UL that I compiled when putting my 912 back together from it's partially disassembled state when I got it. These are NOT all the o-rings in the engine but it is the majority needed and the ones that are the hardest to get to when the engine is assembled. If other o-rings are needed, I attached links to the parts pages and a link to Maryland Metrics so you could find the one needed, cross reference it to Maryland Metric's part number and order it. Like I mentioned earlier, you will have to triple or quadruple your order to get to their minimum order amount. These are NOT rotax parts, but they worked in my engine and thus far, no leaks.

Quantity p/n size brand name description Location Rotax #

> 4 R398-20744 34x2 N/A O-ring Intake to Head 230-910
> 4 R398-20660 19x2 N/A O-ring Coolant socket flange 950-180
> 2 R398-20559 5x1.5 N/A O-ring Starter bolts 950-420
> 1 R398-20736 32x2 N/A O-ring Water pump 90 230-020
> 1 R398-20724 30x2.5 N/A O-ring oil pump 950-410
> 2 R398-17597 11x2.7 N/A O-ring oil pump 250-460
> 1 R398-20849 57x3 N/A O-ring oil pump 430-405
> 1 R398-32557 24.4x3.1 N/A O-ring starter to block 250-140
> 2 R398-20811 47x2 N/A O-Ring Carb Socket to intake 230-300

Made from Viton

Link to Lockwood to find the o-rings. The size is in the description.

Link to Maryland Metrics. Find the size and their part number.

****Following updated additional o-ring information provided by DaveS from St. Paul, Minnesota. Thank you Dave for this contribution and to Jerrytex for the original o-ring post.👍
Referencre update for "O-rings that fit"


Thinking this might be a useful update to Jerrytex's original post from 9 years ago as the firm indicated in the post (Maryland Metrics) has been gone for a number of years; and, another firm, McMaster-Carr, which a fair number of people secure parts from has probably the best coverage available for o-rings, complete with documentation. Good idea to keep Jerry's original post right beside it since he had other very useful information in the post.

Update suggestion below:

This is an update to a post by Jerrytex from several years ago regarding "O-rings that fit". Jerry saved my bacon when I needed a specific o-ring some years back.

The company indicated in the original post, Maryland Metrics, has been gone for several years; and, another firm; McMaster-Carr, which builders/maintainers may be familiar with for other items has just about everything in o-rings a person could use including extensive documentation and selection criteria so a person can figure out precisely what they need.

McMaster-Carr has a lot of mechanical stuff; and, their o-rings are sort of buried under their "sealing" submenu. They have the common o-ring materials which would be used in engines including Buna-N, Viton, Hi temp silicon (like we use on the upper coolant elbows) as well as a long list of exotic materials.

Once a person is in the O-ring section, there is a description of their O-rings and an easy to use O-ring selector which has options for cross section, inch vs metric, ID, OD, width, material, chemical compatibility, min and max temp tolerances and many more parameters if of interest.
They also have Milspec o-rings.

Each package shipped includes the tracking information from the manufacturer on it as well as shelf life info.

Prices on everything has changed in this world; but, the last o-rings I bought from them were about what Rotax charges for one or two but you get 50 in a package (although the quantity may vary depending on type of materials). Mileage can vary.

Dave S
Kitfox 7 Trigear (Flying since 2009)
912ULS Warp Drive

St Paul, MN