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3300 - low oil pressure at high RPM

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SteveR

Joined: 10 Jan 2006
Posts: 226
Location: Aledo, TX

Posted: Mon Sep 20, 2010 8:18 pm Post subject: 3300 - low oil pressure at high RPM

A friend of mine just bought an Arion Lightning LSA with the 3300 engine.  At cruise RPM, the oil pressure is fine, maybe 45 PSI.  At idle it is fine, but I'm not sure what PSI he told me.  The problem is at wide open throttle, during takeoff the oil pressure will drop to about 30 PSI, and at WOT in cruise flight the oil pressure drops to about 30 PSI.



What could be the problem?  He added a washer to the pressure relief valve today after changing the oil but experienced the same problem in a ground run.



Any input would be appreciated.

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Mon Sep 20, 2010 9:31 pm Post subject: Re: 3300 - low oil pressure at high RPM

The resistor type senders are very sensitive to partial grounds. We have the same issues on a FD CT. Fix the grounds to be more solid. Oil pressure senders are the first to show this because they are more sensitive than other instruments to poor grounds. Been there and done that on at least 15+ planes.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

matronics(at)rtist.nl
Guest

Posted: Mon Sep 20, 2010 9:36 pm Post subject: 3300 - low oil pressure at high RPM

Steve,



I am translating your message and replacing the values you gave with the 

range on the oil pressure gauge:



"A friend of mine just bought an Arion Lightning LSA with the 3300 engine. 

At cruise RPM, the oil pressure is fine, in the green.  At idle it is fine, 

but I'm not sure what PSI he told me.  The problem is at wide open throttle, 

during takeoff the oil pressure will drop a bit but stays in the green, and 

at WOT in cruise flight the oil pressure drops but stays in the green".



Unless your engine is an older one where the oil pump plate has not been 

modified for cavitation, there is no problem.



Oh, and the washer does nothing. The relief valve opens at a high pressure 

which you do not reach. Adding a washer will only raise the pressure at 

which the relief valve opens, it does nothing for normal range operation.



Rob



---

flyadive(at)gmail.com
Guest

Posted: Tue Sep 21, 2010 4:12 am Post subject: 3300 - low oil pressure at high RPM

Roger:



Your statement - Is that true of all electrical oil pressure sending units?

I fly mostly Lycoming engines, NOT because I want to just because that is what is on the planes.  When I see LOW oil pressure or HIGH oil temps in flight I do two things:

 1 - Get my hart back under control.

2 - CROSSCHECK - Crosscheck Oil Temp against Oil Pressure and Oil Pressure against Oil Temp.

If you have High Oil Temps AND Low Oil Pressure - YOU GOT A PROBLEM

 If you have High Oil Temps and Normal Oil Pressure - You should expect to see the Oil Temp come DOWN with the nose S&L and cruse power.

If you have Low Oil Temps and Normal Oil Pressure  - You have a bad Gage - More than likely

 If you have Low Oil Pressure and Normal Oil Temps - You have a bad Gage - More than likely

If you have High Oil Pressure and Normal Oil Temps - JUST SMILE - I like that

On GA aircraft it has been the airframe manufacture that set the Oil Pressure requirements on the gage.  BIG FAA MISTAKE.  Cessna wanted to increase the Red Line on oil pressure from 100 PSI to 125 PSI... The FAA would not let them do that.  SOooooo what did Cessna do?  They moved the oil pressure pick up from the rear of the engine to the front AND increased the Oil Pressure..  That increased the Oil Pressure through out the engine whill STILL keeping the Gage Reading at 100 PSI Red Line    Smart Cookies!

 Roger, is there REALLY a reason why you can't increase the Oil Pressure, 45 PSI sure sounds low?  I'm learning your engines, I'm not too bad on Lycoming - Rebuilt a few.

Barry

 



On Tue, Sep 21, 2010 at 1:31 AM, Roger Lee <ssadiver1(at)yahoo.com (ssadiver1(at)yahoo.com)> wrote:

[quote] --> JabiruEngine-List message posted by: "Roger Lee" <ssadiver1(at)yahoo.com (ssadiver1(at)yahoo.com)>

 

 The resistor type senders are very sensitive to partial grounds. We have the same issues on a FD CT. Fix the grounds to be more solid. Oil pressure senders are the first to show this because they are more sensitive than other instruments to poor grounds. Been there and done that on at least 15+ planes.

  

 --------

 Roger Lee

 Tucson, Az.

 Light Sport Repairman - Maintenance Rated

 Rotax Repair Center

 520-574-1080

 

 

 

 

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SteveR

Joined: 10 Jan 2006
Posts: 226
Location: Aledo, TX

Posted: Tue Sep 21, 2010 7:51 pm Post subject: Re: 3300 - low oil pressure at high RPM

Rob,



According to my friend, it was actually below the green at high RPM (indicating 30psi, low redline is 32psi).  The warning light on the panel illuminated, so I think it is probably lower than it should be.  The gauge is an EIS, maybe the model 4000.  My first guess was a bad ground.  Is this gauge a resistor type?  I assume so, being electronic.



My primary question is should a Jabiru exhibit such a large oil pressure drop when RPM is increased (from 45+psi down to 30psi)?  Is that typical?  If not, there is some type of problem, even if it is just instrumentation.



Thanks for the help so far!



Steve Ruse

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Wed Sep 22, 2010 6:42 am Post subject: Re: 3300 - low oil pressure at high RPM

Having a low oil level will cause this because many oils will foam, then you start pump in some air and this reeks havoc on a sender and your internal parts. Some are more prone to foaming than others. If you use an electrical oil pressure sender then yes a poor ground can cause this. These are a resister type and very sensitive to poor grounding. I deal with this a lot in Flight Design CT's. If it were a mechanical type gauge with actual oil in it then no it wouldn't be the cause. Oil pressure senders are notorious for going bad. Like the Rotax, it uses a VDO oil pressure sender and they do go bad. If the pressure goes down on throttling up and then back up when throttle is reduced look definitely at the ground. If the gauge pegs out at the max look at the ground. If it drops to very low like 15-20 psi then most likely a sender or gauge, but I agree that in flight a quick cross checking to make sure it really is a sender and not a real low pressure issue is extremely prudent and I wouldn't fly it until I had a handle on the problem. The only sure way to check these is on the ground. Tie the plane down so you can run up the rpm. Put a mechanical gauge setup in line with the electronic sender and run the engine. Make sure that they read the same. 98% of the time when I do it this way the real engine oil pressure is ok and I find it is just the sender or the ground. So use good diagnostics on the ground and find the problem in an a to b to c to d logical diagnostic pattern. 

p.s.

The sender or the gauge may have the poor ground.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Kayberg(at)aol.com
Guest

Posted: Wed Sep 22, 2010 11:44 am Post subject: 3300 - low oil pressure at high RPM

A Jabiru is not a Rotax by any stretch.  Hence Rotax experience has  little value here.

  

 A Jabiru will run on half a cup of oil, the Rotax will not.

  

 Actually, the Jabiru will do the oil pressure and temperature dance if it  has too MUCH oil!   They do not like being even slightly  overfilled.

  

 That being said, I do not have a  lot of faith in VDO senders.   So I would agree with your suggestion of a temporary mechanical guage!!

  

 Doug Koenigsberg

  

  

  

  

 In a message dated 9/22/2010 10:45:51 A.M. Eastern Daylight Time,  ssadiver1(at)yahoo.com writes:

  	  Quote: 	
		  

Having a low oil level will cause this because many oils will foam,    then you start pump in some air and this reeks havoc on a sender and your    internal parts. Some are more prone to foaming than others. If you use an    electrical oil pressure sender then yes a poor ground can cause this. These    are a resister type and very sensitive to poor grounding. I deal with this a    lot in Flight Design CT's. If it were a mechanical type gauge with actual oil    in it then no it wouldn't be the cause. Oil pressure senders are notorious for    going bad. Like the Rotax, it uses a VDO oil pressure sender and they do go    bad. If the pressure goes down on throttling up and then back up when throttle    is reduced look definitely at the ground. If the gauge pegs out at the max    look at the ground. If it drops to very low like 15-20 psi then most likely a    sender or gauge, but I agree that in flight a quick cross checking to make    sure it really is a sender and not a real low pressure issue is extremely    pruden!

t and I wouldn't fly it until I had a handle on the problem. The    only sure way to check these is on the ground. Tie the plane down so you can    run up the rpm. Put a mechanical gauge setup in line with the electronic    sender and run the engine. Make sure that they read the same. 98% of the time    when I do it this way the real engine oil pressure is ok and I find it is just    the sender or the ground. So use good diagnostics on the ground and find the    problem in an a to b to c to d logical diagnostic pattern.    

p.s.

The sender or the gauge may have the poor    ground.



--------

Roger Lee

Tucson, Az.

Light Sport Repairman -    Maintenance Rated

Rotax Repair  Center

520-574-1080



	


 

  

  [quote][b]

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Wed Sep 22, 2010 9:19 pm Post subject: Re: 3300 - low oil pressure at high RPM

Hi Doug, 



I agree whole heartedly, a Jabiru is not a Rotax, but the gauges, sensors, senders and wire hook ups share many commonalities in wiring and they  are the same company in many cases and have the same issues. The specific engine doesn't really matter. Wiring principles and all the above listed parts share a lot of commonalities.



The exact same rational can be used in different make cars. They are very different, but share electrical needs and wiring with the same principles.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Kayberg(at)aol.com
Guest

Posted: Thu Sep 23, 2010 4:44 am Post subject: 3300 - low oil pressure at high RPM

Hi Roger,

  

 Good point that wiring is shared.   Yes, there is a commonality  in that regard.

  

 However, Jabiru requires CHT's on each cylinder to warrantee the  engine.   Also recomends EGT's on each. Neither are necessary on a  Rotax 912-S.

  

 Conversely a water temp  and water pressure is not needed on a  Jabiru!   They can be quite handy on a Rotax.

  

 I think my real point is that using association as a troubleshooting  technique can be misleading.   The two have totally different oil  systems and components.  No need to "burp" a Jabiru.  Oil cooler lines  are a lower pressure with Rotax.    Rotax engines turn nearly  twice as fast as a Jabiru.  Too much oil in a Jabiru can result in low  oil pressure and high oil temps.  Too much oil in a Rotax doesn't make much  difference....it will just run out the tank overflow.

  

 I know I am preaching to the choir, but just wanted to comment.

  

  

 Doug

  

  

 In a message dated 9/23/2010 1:22:27 A.M. Eastern Daylight Time,  ssadiver1(at)yahoo.com writes:

  	  Quote: 	
		  

Hi    Doug, 



I agree whole heartedly, a Jabiru is not a Rotax, but the    gauges, sensors, senders and wire hook ups share many commonalities in wiring    and they  are the same company in many cases and have the same issues.    The specific engine doesn't really matter.



The exact same rational can    be used in different make cars. They are very different, but share electrical    needs and wiring with the same principles.



--------

Roger    Lee

Tucson, Az.

Light Sport Repairman - Maintenance Rated

Rotax    Repair Center

	


 

  

  [quote][b]

rpf(at)wi.rr.com
Guest

Posted: Thu Sep 23, 2010 8:41 am Post subject: 3300 - low oil pressure at high RPM

Does anyone happen to know the thread type (size) for the oil pressure 

sender on a Jabiru 3300 (1/8-27npt or 1/4-18npt)?



Thanks,

Randy

---

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Thu Sep 23, 2010 11:45 am Post subject: 3300 - low oil pressure at high RPM

As mentioned by Pete here, the thread is metric, but the 1/8 NPT fits  

it. I can verify that I ordered the 1/8 NPT, installed it and it does  

work....on a 2200. This is the case with both of the useable oil  

pressure ports.

Frankly, I don't understand why Jabiru would have tapped this to a  

metric thread, when all (most all, as I've found) of the other  

threads in the engine are good ol' USA threads, that is, either USC  

or USF.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062

Sensenich 62"x46" Wood (summer)

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying...1054 hrs (since 3-27-2006)



On Sep 23, 2010, at 12:30 PM, Randy wrote:



 	  Quote: 	
		   



 Does anyone happen to know the thread type (size) for the oil  

 pressure sender on a Jabiru 3300 (1/8-27npt or 1/4-18npt)?



 Thanks,

 Randy

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

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