Rotax 912 Oil Pressure

[blakemorem]

G"day fellers i was doing the usual taxi out and warm up, maggi checks and fuel pump check and waiting for temps to come up when i noticed if you bring rpm up to about 3000 the pressure will drop to just above yellow(30 psi) and if you go back to idle the pressure comes up to mid green (70 psi). As id recently done an oil change i was worried that i had an air lock in the plumbing. I questioned it with the CFI and it was quite normal as when you get optimum temp the oil pressure regulator valve will allow the oil pressure to jump back to 70 psi. I"m guessing you should wait for it at warm up but its gunna take a while, as i usually wait for carby and oil temp. Does any one know more about this oil pressure range and possible adverse affects or is it ok to blast off and let it do it"s own thing, i"m assuming the pressure changes as the oil thins out. Im just a little concerned i may be risking damage if it"s not in the green when revs are up.Mike.

[birdy]

That was one of the first things i noticed years ago too.The pressure regulation is not just a ball and spring.All iv ever dun is wait for the oil temp needle to lift off the bottom stopper n give it to it, let it sort itself out.Never hada issue.With aircraft situations, theres lots to consider.Warm up at idle, buggerall aorflow over the cooler, not all the oil is warm yet, blast off n suddenly the circulation has sped up n your sucn cold oil, then backoff to cruise rpm with plenty of air pumpn through the cooler n it takes a while for temps n pressures to stabilise.

[RickE]

Sounds pretty normal to me Mike. I had a few oil pressure issues on a new 914 recently. Rotax have a modification for the oil pressure relief valve which I changed but it ended up being a faulty sender which I have been told is pretty common.

[blakemorem]

Yeah thanks fellers i"ve heard the same from another and a little happier. I was just worried i was gunna tear the big end bearing out of it. As ya mentioned Birdy prop pulling air thru the oil cooler it"s gotta regulate flow based on temperature im guessing as the tolerances within may not like sudden changes of temperature. I"m not sure how long ya have to run to get optimum temperature but im guessing it would be close after backtracking up the runway maybe longer in winter i"ll have to pay more attention to it but i"m usually thinking of other things. I generally look at oil and carb temp and blast off.I know the oil level is good and it has a new filter and it"s got the shell aero 2000 oil in it and that"s good stuff as you will drop every tool you pick up it"s that slippery.Mike.

[birdy]

Main thing to watch is that the oil gets to and stays around 80-90c.

[t-bird]

The oil temperature should be between 90 and 110 degrees. The oil level wil increase at lower temps due to condensation that is not burnt off.

[Tsemler]

Glad this come up, as I fired my rotax up for the first time today, it answers one of my questions I"ve got, now I"ve just gotta work out why my rpm is reading 3 times what it actually is on my digital dash, but it"s only on both or left mag, on right mag switch it reads correct. ??????

[blakemorem]

Hey Trent i"m all ECU"d out after Bryce"s innings but its gotta be wiring as the digital readout picks up pulses from CDI. I was gunna suggest the setting on the digital readout but it"s good on right maggi so it"s gotta be the pulses comming from CDI, anyway im guessing you already know all that so i guess i"ll shutup now and let you think about the wiring.Mike.

[Brian]

Anyone who hasnt a oil thermostat fitted to their 912 should seriuosly consider fitting one.

[Tsemler]

Hi Mike,Yep I"m thinking either something to do with ground or switching over the two tach wires for a start, I"ve got the pulse set for 1 per revolution but next time I might just try 3 per rev to just see if it brings the left mag back to normal... If ya have any ideas of what else I could check I"m all ears... Cheers

[blakemorem]

Ahhh, You got me thinking there Trent I remember while i was knuckling out the problem with the Subaru i was looking at the data coming from the cam sensor as it was feeding the fire order, I was surprised to see its a count 1/1,2/1,2,3/1,2,3,4. I"m wondering if the Rotax CDI has the same fire order count although there must be a way to get the right data from both maggis as it"s done with other rotax...just a thought i guess a wiring diagram would be handy for reference i believe you can get this info from Bert Flood or ASRA technical reference. If your taco is working on one maggi it should be set right and functional, its gotta be the wiring yeah and check earthing good old earthing can really cause hassles.Mike.

[JAL]

I was told the 912 uses a pressure pump for oil circulation, so to protect the oil filter, cold oil is bypassed around the filter until it reaches the required temp.