BrendAn Posted July 30, 2022 Posted July 30, 2022 Can you run a 912 at fast idle without a prop. I imagine the gearbox would put a bit of load on it anyway. The reason I ask is I want to warm the motor up in my shed to check it over and change the oil. Being a 4 stroke I can't see a problem but thought I better ask first
Thruster88 Posted July 30, 2022 Posted July 30, 2022 Rotax don't recommend it. All the oil will be in the tank after burping the engine and it will drain out without being hot. 1
facthunter Posted July 30, 2022 Posted July 30, 2022 You'd be better to drain it after a longish flight. A lot of aero engines take about 45 minutes to reach equilibrium temp. Nev 1
Thruster88 Posted July 30, 2022 Posted July 30, 2022 Bit hard to have a longish flight with no propeller 😂
BrendAn Posted July 30, 2022 Author Posted July 30, 2022 1 hour ago, Thruster88 said: Bit hard to have a longish flight with no propeller 😂 It's fully optioned with propeller. I just didn't want to run it in my shed although it would blow the cobwebs out. It's an apartment complex. Can't push it out into the yard and run because shed opens onto street. Why wouldn't the oil warm up . Does it not circulate from tank to engine and back to tank. I can just leave it till after a flight but I was hoping to give it a good service first.
BrendAn Posted July 30, 2022 Author Posted July 30, 2022 1 hour ago, Garfly said: (That was a joke, Joyce. ;- ) What's your problem
Garfly Posted July 30, 2022 Posted July 30, 2022 2 hours ago, Thruster88 said: Bit hard to have a longish flight with no propeller 😂 1 hour ago, facthunter said: That's fairly obvious. Nev. 1 hour ago, Garfly said: (That was a joke, Joyce. ;- ) 8 minutes ago, BrendAn said: What's your problem No problem. We like a good joke on this site. 2 1
BrendAn Posted July 30, 2022 Author Posted July 30, 2022 4 minutes ago, Garfly said: No problem. We like a good joke on this site. No worries. I won't bother asking questions. I will look up the rotax manual.
Thruster88 Posted July 30, 2022 Posted July 30, 2022 18 minutes ago, BrendAn said: It's fully optioned with propeller. I just didn't want to run it in my shed although it would blow the cobwebs out. It's an apartment complex. Can't push it out into the yard and run because shed opens onto street. Why wouldn't the oil warm up . Does it not circulate from tank to engine and back to tank. I can just leave it till after a flight but I was hoping to give it a good service first. 1 minute ago, BrendAn said: No worries. I won't bother asking questions. I will look up the rotax manual. Rotax say not to run the engine without a prop. It probably has more to do with lawyers and arse covering than actual engine damage. There really is no advantage in hot oil for an oil change. 1 1
Garfly Posted July 30, 2022 Posted July 30, 2022 13 minutes ago, BrendAn said: No worries. I won't bother asking questions. I will look up the rotax manual. Lots of crossed wires here. Never mind. 1
Old Koreelah Posted July 30, 2022 Posted July 30, 2022 Brendan, I presume being hot ensures more of the oil drains out and carries more of the gunk with it. Thinking outside the box: who says running the engine is the only way to warm up the oil? During WWII the Swedes kept the oil hot and added it to their fighter planes just before they scrambled. 2 1
pmccarthy Posted July 30, 2022 Posted July 30, 2022 I would change the oil cold rather than try it. 3
BrendAn Posted July 30, 2022 Author Posted July 30, 2022 19 minutes ago, Thruster88 said: Rotax say not to run the engine without a prop. It probably has more to do with lawyers and arse covering than actual engine damage. There really is no advantage in hot oil for an oil change. I will change it cold then. It has a Ryco z134 on it. Should I be fitting a genuine rotax oil filter. I read they have a different bypass setup in them. 1
BrendAn Posted July 30, 2022 Author Posted July 30, 2022 11 minutes ago, Garfly said: Lots of crossed wires here. Never mind. No stress. 1
Thruster88 Posted July 30, 2022 Posted July 30, 2022 1 hour ago, Old Koreelah said: Brendan, I presume being hot ensures more of the oil drains out and carries more of the gunk with it. Thinking outside the box: who says running the engine is the only way to warm up the oil? During WWII the Swedes kept the oil hot and added it to their fighter planes just before they scrambled. With the 912 all the gunk gets returned to the tank and some will settle to the bottom. The top of the tank is removable if one is wanting to clean the bottom. 2 1 1
facthunter Posted July 30, 2022 Posted July 30, 2022 Disconnect the oil pipes carefully and cover the ends and clean out the tank with a pressure gun and long brush. Be careful with volatiles and flame and use lint free brush or rags. All I was trying to do was answer a proper question. It's not easy to purge all the oil from this system and if you do I would suggest you prime the delivery side of things before starting the engine. Nev 1 1
Old Koreelah Posted July 30, 2022 Posted July 30, 2022 3 minutes ago, facthunter said: It's not easy to purge all the oil from this system and if you do I would suggest you prime the delivery side of things before starting the engine. Nev Beats me why engines don’t have an electric pump to get oil flowing before startup. 1
IBob Posted July 30, 2022 Posted July 30, 2022 I recommend downloading the Rotax Line and Heavy Maintenance manuals: they're free. It tells you how to do an oil change, including important details like DONT turn over the engine once you have begun to empty the oil out. The idea is to keep the lifters flooded and so avoid getting air in them............. 1 2 2
facthunter Posted July 30, 2022 Posted July 30, 2022 (edited) Good idea, OK, but something else to go wrong in the big scheme of things. I always prime a new engine fully before starting it. You can hear the air getting out of the lifters and filling the pushrods. I was going to add that getting all the oil out need not be the aim here for the reasons I bob has mentioned but if there's sediment in the tank it's worth cleaning out Nev Edited July 30, 2022 by facthunter 1
IBob Posted July 30, 2022 Posted July 30, 2022 Yes, Facthunter, that's why I'm recommending the manuals: they also contain the routine for priming a new 912, which is done with compressed air...... 2 1 1
IBob Posted July 30, 2022 Posted July 30, 2022 It's a $30,000+ engine. I would be following the manufacturer's recommendations, including when it comes to oil and filter. 2 2
Thruster88 Posted July 30, 2022 Posted July 30, 2022 4 minutes ago, IBob said: I recommend downloading the Rotax Line and Heavy Maintenance manuals: they're free. It tells you how to do an oil change, including important details like DONT turn over the engine once you have begun to empty the oil out. The idea is to keep the lifters flooded and so avoid getting air in them............. I agree it is a good idea to keep the external oil lines full however all new Rotax 912 and those getting a five year rubber replacement are assembled with empty lines (have just done one). The lifter thing I think is an old wives tale, yes air could get in there but it will sort itself out. Yes follow the procedure to purge air out and get oil pressure before starting. The fact that oil remains in the external lines and cooler when changing oil shows that getting a maximum drain with hot oil is pointless. 2 1
IBob Posted July 30, 2022 Posted July 30, 2022 With respect, Thruster, I'll be an old wife and take the manufacturer's advice, rather than yours....) 4
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