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Oil Pressure IGSO 540 B1A

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Jerry Sprayberry

Joined: 10 Jan 2006
Posts: 15
Location: Summerville, GA

Posted: Wed Aug 08, 2007 5:18 am Post subject: Oil Pressure IGSO 540 B1A

Moe, and all Commander  Folks, 

Thanks for your reply  on the Oil Pressure, Input's from the other AC 680 Owners and Drivers will be  appreciated. 

I was not aware that  the Oil Pump had a history of being weak, (Morris) said it was capable of up to  400 PSI. 

     1.    I have not checked my O/P Gage, It was ok on  the    old Engine 

     2.    Columbia Aircraft Services has checked the Pressure at four  different places and it is the same. 

     3.    NO. The Pressure drop's to around 63 PSI in flight, Green  Band is 70-80. 

     4.    The O/P is OK for Ground OPS with a lot of power, 1500  Plus. 

Jerry,<?xml:namespace  prefix = o ns = "urn:schemas-microsoft-com:office:office"  /> 

 Thanks for the tip, I  will contact <?xml:namespace prefix = st1 ns =  "urn:schemas-microsoft-com:office:smarttags" />Gary. 

 Regarding the oil  pressure problem.  It is generally accepted that the oil pumps on the IGSO  540 series are too small.  I can’t remember the GPM (gallons per minute),  however, this has been, as I understand it, a long standing problem.  Once  the pump has in-adequate volume, no amount of spring shimming will raise the oil  pressure.  Some suggestions:    Have you checked the accuracy of    your oil pressure gage?  (Laugh, but I have heard some real horror    stories)    
Screw an oil pressure gage into    the oil galley at the front of the engine and compare the oil pressure on the    two gages.  Lycoming has a maximum differential that is acceptable,    again, I can’t remember what it is, but will look it up for you if    necessary.    
Will the oil pressure stay in the    green while in flight?    
Will the engine maintain a minimum    of 35 PSI at hot idle and about 1,500 RPM (minimum for the fuel pump computer    to work)?  

 

Regards, 

 

Moe 

N680RR 

680F(p)

 Jerry Sprayberry

706  506-3167

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kamala(at)MSN.COM
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Posted: Wed Aug 08, 2007 6:25 am Post subject: Oil Pressure IGSO 540 B1A

js,  there is a ball/socket on the io 720 that when worn or corrosion will cause a lower o/p reading.  interestingly enough it will decrease w/ altitude and increase on the way back down.  there is a factory fix but suspect at overhaul is most cost efficient time to do it.  mason

 [quote]  From: capnspray_611(at)hotmail.com

To: commander-list(at)matronics.com

Subject: Oil Pressure IGSO 540 B1A

Date: Wed, 8 Aug 2007 09:16:29 -0400

Moe, and all Commander Folks, 

Thanks for your reply on the Oil Pressure, Input's from the other AC 680 Owners and Drivers will be appreciated. 

I was not aware that the Oil Pump had a history of being weak, (Morris) said it was capable of up to 400 PSI. 

    1.    I have not checked my O/P Gage, It was ok on the    old Engine 

    2.    Columbia Aircraft Services has checked the Pressure at four different places and it is the same. 

    3.    NO. The Pressure drop's to around 63 PSI in flight, Green Band is 70-80. 

    4.    The O/P is OK for Ground OPS with a lot of power, 1500 Plus. 

Jerry, 

 Thanks for the tip, I will contact Gary. 

 Regarding the oil pressure problem.  It is generally accepted that the oil pumps on the IGSO 540 series are too small.  I can’t remember the GPM (gallons per minute), however, this has been, as I understand it, a long standing problem.  Once the pump has in-adequate volume, no amount of spring shimming will raise the oil pressure.  Some suggestions:  Have you checked the accuracy of your oil pressure gage?  (Laugh, but I have heard some real horror stories)  
Screw an oil pressure gage into the oil galley at the front of the engine and compare the oil pressure on the two gages.  Lycoming has a maximum differential that is acceptable, again, I can’t remember what it is, but will look it up for you if necessary.  
Will the oil pressure stay in the green while in flight?  
Will the engine maintain a minimum of 35 PSI at hot idle and about 1,500 RPM (minimum for the fuel pump computer to work)?  

Regards, 

Moe 

N680RR 

680F(p)

 Jerry Sprayberry

706 506-3167

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mashley2(at)kc.rr.com
Guest

Posted: Wed Aug 08, 2007 7:13 am Post subject: Oil Pressure IGSO 540 B1A

Hello Jerry,

 I am not an engine expert but I have a  little hydraulic experience. Here is a viewpoint from a hydraulic  perspective. 

  

 Pumps - Oil pressure is the measurement of  resistance to flow. A pump does not produce pressure, it produces flow. The pump  has a pressure rating that is the pressure that it can withstand before failure.  With that being said, low oil pressure means that the pump is not producing the  same flow as before (defective or worn pump), or the oil has found an alternate  path of least resistance (a crack or a missing internal plug in an oil  galley).

  

 The function of a relief valve is to protect the  hydraulic system from going over a certain pressure setting. A relief  valve is a normally closed valve that only opens when oil pressure exceeds the  spring setting. A faulty relief valve (weak spring or valve does not completely  reseat therefore it is leaking) will also cause low oil pressure because it is  opening before the desired pressure setting.

  

 The most likely cause of low oil pressure would be  a pump not producing correct flow (faulty or worn pump) or relief valve opening  before desired system pressure (spring setting) is achieved (faulty spring or  valve seat).

  

 I hope this helps!

 Myron Ashley

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CloudCraft(at)aol.com
Guest

Posted: Wed Aug 08, 2007 7:28 am Post subject: Oil Pressure IGSO 540 B1A

Jerry,

  

 In my days of IGSO-540 flying, it was suggested that an oil pressure drop that could not be adjusted at pump output was a sign of a main bearing going bad.

  

 Hard to imagine that with a recent o/h engine but stranger things have happened.

  

 Wing Commander Gordon



AOL.com.

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moe(at)rosspistons.com
Guest

Posted: Wed Aug 08, 2007 8:57 am Post subject: Oil Pressure IGSO 540 B1A

Jerry,  

The oil pump on these engines seems to be capable of lots of pressure, but not much volume.  It is entirely possible to have a pump which will put out lots of PSI pressure at a very low volume, but as the volume demand increases (too much clearance between the rod and/or main bearings and the crankshaft, a missing oil spray nozzle for the underside of the pistons, ect.) the pressure goes down dramatically. Myron and Wing Commander Gordon are correct. Generally, if the engine is very worn with lots of clearance between the worn parts, which allows the oil to escape back into the sump using the path of least resistance, your biggest problem will be at hot idle (low oil pump speed and lots of clearance for the oil to squirt out at).  When I had two very worn engines in my bird the oil pressure would barely stay in the green in the air, however, on the ground and hot there was not enough oil pressure (below 35PSI) to make the fuel metering system work, so it would run so rich that it was hard to keep it lit when landing, and you had to manually lean it out on the roll out.  

   

  Since you can maintain pressure at high idle (1,500 RPM) on the ground, but not at higher RPM, based on my old race car experience, be sure that the inlet oil line from the tank to the pump does not have a “flapper” in it that is reducing the amount of oil that is available for the pump.  Check all of the fittings on the inlet side for restrictions.  In short be sure that the line from the dry sump tank to the oil pump is not restricted.  Did you say that the pump relief spring was already shimmed with seven washers when it came from Perf. Aero, or did someone else add these at a later time?   

   

Regards,  

   

Moe   

         

  

From: owner-commander-list-server(at)matronics.com [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Jerry Sprayberry

 Sent: Wednesday, August 08, 2007 6:16 AM

 To: commander-list(at)matronics.com

 Subject: Oil Pressure IGSO 540 B1A  

  

     

Moe, and all Commander Folks,  

Thanks for your reply on the Oil Pressure, Input's from the other AC 680 Owners and Drivers will be appreciated.  

I was not aware that the Oil Pump had a history of being weak, (Morris) said it was capable of up to 400 PSI.  

    1.    I have not checked my O/P Gage, It was ok on the    old Engine  

    2.    Columbia Aircraft Services has checked the Pressure at four different places and it is the same.  

    3.    NO. The Pressure drop's to around 63 PSI in flight, Green Band is 70-80.  

    4.    The O/P is OK for Ground OPS with a lot of power, 1500 Plus.  

Jerry,  

Thanks for the tip, I will contact Gary.  

Regarding the oil pressure problem.  It is generally accepted that the oil pumps on the IGSO 540 series are too small.  I can’t remember the GPM (gallons per minute), however, this has been, as I understand it, a long standing problem.  Once the pump has in-adequate volume, no amount of spring shimming will raise the oil pressure.  Some suggestions:    Have you checked the accuracy      of your oil pressure gage?  (Laugh, but I have heard some real horror      stories)   
Screw an oil pressure gage into      the oil galley at the front of the engine and compare the oil pressure on      the two gages.  Lycoming has a maximum differential that is      acceptable, again, I can’t remember what it is, but will look it up      for you if necessary.   
Will the oil pressure stay in      the green while in flight?   
Will the engine maintain a      minimum of 35 PSI at hot idle and about 1,500 RPM (minimum for the fuel      pump computer to work)?    

   

Regards,  

   

Moe  

N680RR  

680F(p)  

    

Jerry Sprayberry

 706 506-3167  

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Jerry Sprayberry

Joined: 10 Jan 2006
Posts: 15
Location: Summerville, GA

Posted: Wed Aug 08, 2007 1:22 pm Post subject: Oil Pressure IGSO 540 B1A

Moe,

  

 The Engine was delivered in a crate with  Performance Engines written on all sides.

 I unpacked the engine and removed the clear plastic  wrapping myself, The washers were in the regulator.   

  

 We found the washers when we tried to adjust the  pressure to 75 PSI at 2200 RPM.

  

 JS

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