First Time Coolant Fill 915iS

Do you have a thermostat? If not just fill the coolant at the expansion tank and it will find its way through the system. Then run it a while and then check the level in the expansion tank. Fill the reservoir tank about 2/3 full and then after the run just check the levels. I do a ton of Rotax five year rubber changes. I just fill the expansion tank and have never had an issue.

Thanks Roger.

Where would I find quantities and mixing ratios for coolant / distilled water?

Use something like Dex Cool 50/50. Depending on your coolant system it takes aroughly 3/4 gallon. Dex Cool 50/50 with the orange cap is extended life coolant. Almost everyone i know uses it.

You will find these instructions in the Rotax 915iS Line Maintenance Manual, Section 12-10-00, page 4, under Coolant Check/Replenish.

The process for filling the coolant system is not as involved as the oil system. We have included this section of the manual in the attachment.

SI 915 i 001R8, Selection of Suitable Operating Fluids for All ROTAX 4 Stroke Aircraft Engines, is also included in the attachment for reference regarding the type of coolant required for your 915 engine.

Dex Cool 50/50 is listed in the Rotax fluids