Tappet cover screws stuck

·         Rob Turk

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When I need to access my tappets, the cover screws are always incredibly hard to remove and when they release, they do so with a loud snap. I always tighten them to JEM0001-8 torque spec, but even less than an hour later, without running the engine, the screws take a lot more torque to release than they were tightened with. They appear seized. I have just stripped one of the heads and it has taken a lot of effort to remove the damaged screw.

Does Jabiru recommend any anti-seize or lubricant on these screws to avoid this? Other tips or tricks?

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·         Doug Smith

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Hi Rob,
The *snap* noise is typical for those screws. We use high quality Alley key drivers and replace them when they start to look a little worn. I've also always made sure that I use a square-tipped driver for those too, not a ball-tipped driver.

The screws also get replaced if their heads start to wear or feel "soft" when tightened... In my experience they're not something that needs to be replaced often though so a high-quality square-tipped driver might address a good portion of your issues.

You could also try a little Loctite C5-A or equivalent (Copper-Based Anti-Seize Lubricant).

Regards,
Doug.

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·         Rob Turk

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Thanks for the quick reply, Doug.

I am using a square tipped driver from SnapOn and make absolutely sure it is fully inserted before trying to loosen the screws. The amount of force needed just seems excessive.

I'll try some copper-based anti-seize as you mentioned. I also have 24 new screws on their way from the German Jabiru dealer. Perhaps I'm putting this on my annual or 100-hour list to replace them, just in case.

Thanks!
Rob