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Oil change small drama!


Buckaroo

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I went to do my first oil change on my 2007 CTSW and quickly found my first obstacle. The fricken oil filter wouldn't clear the exhaust pipe. Then figuring I'd have to loosen the exhaust pipe found I was missing the wrench for that.

 

All in all it took me 30 to 40 minutes with tank empty and filter unscrewed but stuck by the exhaust pipe. I finally got things sorted and burped the motor.

 

Question: with that long time with empty tank and dislodged filter how can I tell if the oil system didn't get air in the lines? It gurgled fine after new oil.

 

 

Thanks

Dave

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I was told to pull 4 plugs out after refill oil and rotate prop until you see oil pressure on the gauge, then

install plugs, recheck oil and fire it up.Someone correct me if I am wrong?

 

I've never heard of any such thing.  Yes, the filter its tight around the exhaust, but you can get a strap wrench in there.  If you are strong you don't even need a wrench though the first turn will be hard.  

 

My procedure is:

 

- Burp engine

 

- Drain oil from tank

 

- Remove filter

 

- Install new filter

 

- Remove and check mag plug, then replace and safety wire

 

- Close drain plug on oil tank

 

- Add oil

 

DONE.  I've never heard of anybody removing plugs or checking the oil pressure gauge for an oil change.  If there is oil in the tank, you will see pressure on start up.  You can pull the prop through a couple of times if it makes you feel better, but I don't think it serves any real purpose.  There is oil in the engine, there is oil in the tank.  Pressure is assured unless your oil pump chose that exact moment to quit.  You are basically doing the same thing on your first start after the change, without removing any plugs.  Also, you won't see pressure on the gauge unless the master is on, and if the master is on I am NOT pulling the prop through.  Sounds like a recipe for trouble.

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Hi Dave,

 

Loosen the front two exhaust pipes and push the muffler to the left side. Then tighten the exhaust stud nuts back up to 135 in/lbs. make sure the exhaust nuts or protruding studs are equal so there is not one or the other cocking the flange in one direction.

 

 

Procharger,

 

Your info was given to you wrong. After the oil and filter change we need to "Vent" the system. You MUST leave all the plugs in otherwise you will not have any crankcase pressure to return oil Just fill and rotate the prop 15-20 times to fill the oil filter. In venting you don't care about oil pressure.

What your method id is a halfway attempt to "PURGE" the system without any air pressure hook up or return oil tank hose off.

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Hi Andy,

 

You should at least rotate the prop and that will prefill the oil filter before start.

 

I do that, but didn't think of it as a requirement, since the starter does the same thing when you first start it.  The first few turns of the prop will be on a "dry" filter, whether you do it by hand following the change or let the starter/engine do it for you on first start, correct?  Am I missing something?

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In Figure 79-3 of the 912 Heavy Maintenance Manual, it appears that the oil pump's output passes through the oil filter before pressurizing the main oil gallery.

 

So, if the filter is filled with air after a filter change, it may be possible that the engine starts without pressure in the main oil gallery. If the filter is full with oil, there would be no delay in pressure buildup in critical bearing locations.

 

So, in theory, a full filter reduces the potential for the loading of bearing with forces that occur when the engine runs while the bearings are not fully pressurized with oil (obviously for a short period of time).

 

Whether this matters at all to engine longevity or reliability, I have no idea.  But, given the oil system design, I will always pull the prop through many blades before starting the engine after a filter change.  

 

The 912 Maintenance Manual recommends that the engine be cranked by hand "approximately 20 turns" after an oil change.  It makes no mention of doing so after an oil filter change (?) but also appears to make the assumption that both are done at the same time.  

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All you do is pull switch to turn on battery, which then turns on Dynon, the key is not turned on so no

danger there, I turn prop with plugs out so the engine will turn freely and quickly until I see

pressure on the gauge,which can take about 30 to 45 seconds by hand, no harm no foul.

This is the way I have done it since owning the plane3 years. :D

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Hi Procharger,

 

"This is the way I have done it since owning the plane3 years.  :D"

I mean no disrespect, but,,

 

You may have done it this way for a long time, but isn't the right way and isn't taught in any class this way. The one big reason is all you're doing with the plugs out is filling the bottom of the crankcase full of oil and it has no way to get returned to the oil tank which also may cause the removal of air in the oil system to be poorly done. Having oil pressure does nothing about telling you how much oil or air there is in the filter.

 

The whole idea for rotating the prop after the oil change with the plugs in is to vent air out of the filter and pre fill it with oil all the while pumping oil back to the tank to prevent rising oil levels in the crankcase. This is why Rotax calls this VENTING and not purging.

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Hi dave,

 

Nothing magical or hard to do in maint. or flying. It's just something new and different to learn.  All this info is out there. There is no one way to land. Find something that works for you. For examples some like idle only landings some leave some rpm into touch. Some like 30 flaps, but most may favor 15 flaps for a normal landing. You should learn them all and be comfortable with them all. Then pick something that you prefer. Doing things like your neighbor isn't always best. Be flexible and open minded. Only having one tool in your mental toolbox isn't your best preparation for your flying career.

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Hi dave,

 

Nothing magical or hard to do in maint. or flying. It's just something new and different to learn. All this info is out there. There is no one way to land. Find something that works for you. For examples some like idle only landings some leave some rpm into touch. Some like 30 flaps, but most may favor 15 flaps for a normal landing. You should learn them all and be comfortable with them all. Then pick something that you prefer. Doing things like your neighbor isn't always best. Be flexible and open minded. Only having one tool in your mental toolbox isn't your best preparation for your flying career.

I agree Roger I think this is the fun part of owning this bird. It is full of personality and is really fun to fly. I can grease the landings but am struggling a bit with rudder coordination. I am very cautious when it comes to pattern work and rudder control. Thoughts of the Sheriffs mishap are on my mind while in the pattern.

 

All said about the oil situation do you think I'm ok with mine? Any easy way to test the system? I would think the gurgle would tell one the system is pumping with no air!????

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Roger, whether you are spinning it with the plugs installed or not doesn't matter you are still pumping oil through the system and filling the oil filter. If you are worried about the small amount of oil that accumulates in the bottom of the crankcase you can reinstall the spark plugs and burp the engine. Personally if the oil is on the flat of the dipstick I wouldn't worry about it.

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Hi Tom,

 

 

I agree oil still moves it just isn't the way taught. No good reason to just pump oil into the crankcase and then have to rotate it all over again just to remove it and get an read on the level.  This is why they teach to leave the plugs in and then you can check the oil level after you quit turning the first time instead of doing it twice.

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After cleaning the oil tank, the manual calls for purging the system (SI-912-018), which includes removing one plug per cylinder and rotating the prop. Maybe this is where the confusion comes from. But my question is, why is pulling the top off of the oil tank any different from draining all the oil out? It seems you'd be draining some from the lines either way.

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My question was not answered, let me re-phrase:  Why is it better to turn the engine by hand with a dry filter than by the starter and engine turning it by starting the engine during those first 20 or so turns?  After all, any surfaces that are dry are going to be dry for the same number of rotations, one would think the wear caused would be the same.  

 

I'm sure there must be a reason this is recommended, I just don't know what it is.

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I'll try to answer your question, because your engine may start after 2 rotations when starting so

you will not get the 20 turns or more  that may or may not be required before starting.

 

Old saying from where I used to work," I've been doing it that way for 20 years" my reply

is maybe you have been doing it wrong for 20 years? There's always more than one way

to skin that cat. No disrespect to anyone here.

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I used the proper filter wrench Roger Lee recommended awhile back. The filter was off the threads but would not rotate out and off. I had two AP mechanics with me that scratched their heads over the situation. I didn't have the proper wrench with me so ended up using a small crescent wrench on the exhaust pipe bolts. The AP's happened to be there flying their planes that day.

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I'll try to answer your question, because your engine may start after 2 rotations when starting so

you will not get the 20 turns or more  that may or may not be required before starting.

 

 

The engine will still be turning the same number of revolutions "dry" before oil gets to all the parts.  My question is why is it any worse for it to happen when running than by hand?

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