valve cover bolt

by Roger james Larson in General Tech Discussion 6 years ago

I am new to this forum and tried searching this topic but was unsuccessful. Maybe there is a better way to search. My question is: Do valve cover bolts need some kind of Loctite on them on the Rotax 912uls? I have a leak on one and need to re-torque it. So would i pull the bolt completely off and then use Loctite on the bolt?

Or is it possible to just torque the bolt now without pulling the bolt off.

If no loctite is necessary can someone explain why we would not be worried about the valve cases falling off and going into the prop?

Re: valve cover bolt

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 7.97k

According to the manual... No Loctite needed.

If it is leaking there is a problem with the O-Rings.
I would remove the cover and inspect, clean, or replace them.
There is enough give in the cover to act like a giant lock washer.
Tighten to 10Nm (90in-lb) according to the maintenance manual.

There should be the big o-ring at the outer edge and a small one on the inside of the cover sealing the bolt.
There is a flat washer under the bolt head on the outside.

There is no risk of a valve cover falling off and damaging the prop.
Before it ever became so loose that it could fall off, The loose cover would not allow the crankcase to pressurize and none of the Oil would be returned to the Oil Tank and the engine would seize up and stop.
The propeller would be fine! :ohmy:

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: Andrew Dunning

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Re: valve cover bolt

by Roger Lee » 6 years ago

Roger Lee

126 5.14k 4.62k

p.s.
Sometimes you can’t get it to stop. For those that have it it is usually an ooz and not a full blown drip. I have tried on some up tp 4 different sets of “O” rings, slight over tightening, sanding the valve cover face and applying Loctite 598 which is what we use on the gearbox and it still oozed. Sometimes it can be stopped. It is usually more annoying than a problem.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: valve cover bolt

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 7.97k

If you get one that refuses to stop leaking you might try using "Permatex Aviation Form-A-Gasket Liquid Sealant."
Paint a light layer on both surfaces and let it thicken for an hour before assembly.
Don't worry, it won't harden in a year, so there is no rush.
It will still flow under enough pressure.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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Re: valve cover bolt

by Roger Lee » 6 years ago

Roger Lee

126 5.14k 4.62k

The Loctite 598 is used by GM and other motor organizations for high vibration surfaces for sealing metal to metal surfaces. This is one reason we use it. It is the equivalent of Loctite 5910 from Europe.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: valve cover bolt

by Roger james Larson » 6 years ago

Roger james Larson

9 21 0

Well i torqued them to 90 inch pounds and no more leaks in several hours of flying. So hopefully problem solved.

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valve cover bolt

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