Replace ALL tappets?

Hi Matt,

Since the Sling solution is quiet involved I would do one more oil purge just to make sure and rule out any oops. Maybe a different way than you did. There are two ways. One way with all plugs in and one way with the top ones out. I prefer without plugs and I ALWAYS do it twice just to make sure. It only takes a few extra minutes to spin the prop again. I rotate the prop about 80 times in a minute. The pressure on the instruments is usually around 55 psi during the purge I do. I've never had a soft lifter this way. I've done hundreds of oil purges. Then check it again. Then run the engine a few minutes and check the tappet again. Usually you're successful. 

A couple of things to note:

#1 - The Rotax video Tip #15 states to run the engine at 3500 RPM for 5 minutes and check the lifters again, but doesn't say what to do if they won't pump up even after the 2nd test run. - https://www.rotax-owner.com/en/videos-topmenu/free-videos/685 The Video is supplementary information only and the instructions found in SI-915 i-003 supersedes it.

#2 - The Rotax 915iS Installation manual doesn't state anything in regards to checking If the lifters are "pumped up" by inspecting the gap between the rocker arm and valve, however, the Rotax 912iS Installation manual does - https://www.rotax-owner.com/pdf/IM_912_iSeries_ED2_R1.pdf The Rotax 912iS Installation manual also states the following - Replace hydraulic valve tappet If a hydraulic valve tappet still malfunctions after several engines runs, it must be replaced and the valve spring support must be inspected for wear.

#3 - SI-915 i-003 - section 3.4) Replacement of components states: If a hydraulic valve tappet still malfunctions after several engine runs, it must be replaced and the valve spring support must be inspected for wear. All work has to be performed in accordance with the latest Maintenance Manual for the respective engine type. https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912-018r2.pdf

If Sling in South Africa (Also directly linked to a Rotax Distributor) is wanting you to return the engine, and they will replace it with a new one, I would do exactly that! It clearly states in the Service Instruction that not only does a lifter have to be replaced, but the valve spring support must also be inspected for damage and excessive wear. It's much easier to provide you with a new engine than it is to worry about if an inspection procedure and lifter replacement were done correctly.  

I agree with Rotax Wizard before you just take it off and send it back.

"#1 - The Rotax video Tip #15 states to run the engine at 3500 RPM for 5 minutes and check the lifters again, but doesn't say what to do if they won't pump up even after the 2nd test run."

Rotax Wizard,

Just curious.

How many times have you ever heard of this actually happening?? 

"Rotax 912iS Installation manual also states the following - Replace hydraulic valve tappet If a hydraulic valve tappet still malfunctions after several engines runs, it must be replaced and the valve spring support must be inspected for wear.

"#3 - SI-915 i-003 - section 3.4) Replacement of components states: If a hydraulic valve tappet still malfunctions after several engine runs, it must be replaced and the valve spring support must be inspected for wear. All work has to be performed in accordance with the latest Maintenance Manual"

We (Rotax-Owner) have seen several engines with stubborn lifters that won't pump up and require replacement. The replacement of the lifters and inspection of components should be done by someone who is qualified, with the proper training, tooling, and a proper facility as it is not a simple procedure. 

This is why we agree with Sling to replace the engine with a new one. 

Thank you for the replies.

There is a qualified "heavy" shop a couple hours away.  Since replacing an offending tappet is an acceptable procedure per the Rotax IM I think I would rather have that done by a qualified tech than R&R a whole engine.