Engine Squeak

by Stuart Johnson in 912 / 914 Technical Questions 13 years ago

When I turn my engine over by hand (usually after flight to check the oil level) I sometimes get a squeak that seems to come from the gearbox near the propeller hub. It seems to be more pronounced when the engine is warm. Any ideas if this is a problem, or what causes it?

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Re: Engine Squeak

by Roger Lee » 13 years ago

Roger Lee

125 5.12k 4.53k

Hi Stuart,

I can tell you exactly what this is and you may be skeptical, but we can fix it. It may be a combo of two things, but possibly just one.
First out of curiosity what oil are you using? This is one of the issues. It will be the low ZDDP (a zinc phosphorous compound) additive. This is why motorcycle oil and the better oils are important.

The second issue that adds to this is usually, but not always, a low slipper clutch friction torque.

What causes the squeak is actually a metal to metal rub from lack of ZDDP metal protection and sometimes coupled with low slipper clutch torque from the gearbox.

Let me know on the oil type and we can get you fixed. If you have your slipper clutch torque I would like to know that too.

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

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Re: Engine Squeak

by Stuart Johnson » 13 years ago

Stuart Johnson

2 4 0

The oil I use is Pennzoil 20-50 motorcycle oil (not a synthetic). The friction torque has been running about 300 in-lbs for the last several years.

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Re: Engine Squeak

by Roger Lee » 13 years ago

Roger Lee

125 5.12k 4.53k

Hi Stuart,

There is both problems. Get rid of the Pennzoil before you cause any damage. It is a long term issue not one you will see today. The gearbox is your is trying to tell you something. You should not be using a straight mineral based oil. It does not have the protection between metal parts in a highly mechanical close tolerance environment that you need. You are also loosing your shear protection which basically means your are loosing some viscosity. Most of the big touring motorcycles and most of the real hard riders won't use straight mineral based Pennzoil. Use a good semi or full synthetic and with the proper levels of ZDDP the squeak will go away, but first you need to get that gearbox re-shimmed. The normal torque I usually see is anywhere from 440-490 in/lbs with the average at 465 in/lbs. Too low a slipper torque will cause damage too.

You do those two things and you will have one happy gearbox and you will be too.

I'll see if we can't get something in a blog on oil soon for everyone so they know what's in an oil and why we can't use car oils and why we need a good motorcycle additive package. There are not so good motorcycle additive packaged oil.

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

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Re: Engine Squeak

by Stuart Johnson » 13 years ago

Stuart Johnson

2 4 0

I hope I haven't done too much damage. I've been using the pennzoil since I bought the engine in 2005. That was the recommended oil then and I never questioned it. I will replace with a synthetic. Any recommendations? Also, is the shim procedure in the maintenance manual. I haven't found it so far.

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Re: Engine Squeak

by Roger Lee » 13 years ago

Roger Lee

125 5.12k 4.53k

You need to make up your own mind on oils, but here are a few of my favorites from solid research and field experience.

Oil topics can be a very hot topic to say the least. I might have to sleep with one eye open tonight. :lol:

Full Synthetic: (not in any order) Use with auto fuel only.

Mobile One Racing 4T 10-40W, Mobile 1 V-Twin 20-50W, Amsoil 10-40W or 20-50W
All these full synthetics are good oils and have a good additive package and base stock oil.

Use with 100LL or auto fuel.
Semi Synthetic: Aero Shell Sport Plus 4 10-40W, Golden Spectro 4 10-40W or 20-50W

As of this writing Golden Spectro 4 semi synthetic 10-40W or 20-50W may be a better choice because I believe it has the advantage over Aero Shell Sport Plus 4. Aero Shell Sport Plus 4 was developed in England and it is Mfg. there. I haven't found anyone in the US that knows diddly about its properties. Aero Shell's base stock and low 800 ppm ZDDP additive amongst a few other items cause this not to be as good a choice.
ZDDP (Zinc Dialkyl-Dithio-Phosphate) :woohoo: is a sacrificial coating on metal parts to keep parts from going metal to metal. If it is of a too low a ppm then that protection is very poor at best.
I have been told they are going to reformulate next year with a new base stock and up the ZDDP level to around 1500ppm.

From all the research I have done, these oils contain good, high quality base stock oils and sufficient additives to support the engine.

I hope this helps and doesn't throw more mud into your decision. :whistle:

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

Thank you said by: Stuart Johnson

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