78 J Oil Pressure Gauge problem

[wiseng]

I have a problem with the oil pressure indication.  I have replaced the pressure sending unit twice and have come to realize it must be the gauge.  It sticks close to zero and will suddenly come alive and indicate the correct pressure.  I have taken the glare shield off and all the top row instruments are in a can.  Anyone seen this?

[N201MKTurbo]

There is a circular plastic connector for the gauge cluster. Take it apart and clean the pins and put it back together. If that doesn't fixit then take apart the big cannon plug on the firewall and clean it.

[anthonydesmet]

  On 7/18/2018 at 9:54 PM, wiseng said:

I have a problem with the oil pressure indication.  I have replaced the pressure sending unit twice and have come to realize it must be the gauge.  It sticks close to zero and will suddenly come alive and indicate the correct pressure.  I have taken the glare shield off and all the top row instruments are in a can.  Anyone seen this?

Expand  

Kind of, When I first got my Mooney at the pre-buy the airplane ran up fine on the ground in the morning.  Three days in a row I went to go execute the pre-purchse flight in the afternoon and on start up the oil pressure would not come up.  First time it came off the peg a little then froze, second and third time wouldn't come up at all.  The following two mornings the mech went and troubleshot the transducer, lines, connections, etc and started the engine and oil pressure came up each time but not in the afternoon when I went to start up for the flight.  Finally I told him to swap the gauge with a J in the hangar.  Oil pressure came right up at start later that third afternoon.  Best he could tell was that sitting in the Florida heat in July caused something in the gauge to swell and wouldn't let the needle move.  We took the gauge and put it in his office while I flew then when I came back we swapped it out again.  I started up and the gauge worked after sitting in the A/C for a couple hours.  I called LAZAR and got another gauge the next day.......just throwing out possibilities. 

[wiseng]

Did you buy the complete instrument cluster from Lazar?

 

Thanks

[rrbeck11]

I have a ‘78 J with the same intermittent problem: sometimes on engine start he pressure gauge reads 0.  We have replaced the ‘ducer, checked and cleaned the connectors and terminals, and replaced he wiring.  When the pressure is reading normal it is solid as a rock.  It looks like we’re going to the cluster next.  Any advice on sources for the cluster?  Can you replace a gauge within the cluster, or do you have to replace the whole thing?

 

Randy

[wiseng]

Randy-The plane is in annual at present.  I had them recheck the wiring etc.  Since Lazar no longer sells the instrument cluster for this plane.  I am sending the can off to have the OP gauge rebuilt.  

 

David

[ArtVandelay]

  On 8/18/2018 at 2:27 PM, rrbeck11 said:

I have a ‘78 J with the same intermittent problem: sometimes on engine start he pressure gauge reads 0.  We have replaced the ‘ducer, checked and cleaned the connectors and terminals, and replaced he wiring.  When the pressure is reading normal it is solid as a rock.  It looks like we’re going to the cluster next.  Any advice on sources for the cluster?  Can you replace a gauge within the cluster, or do you have to replace the whole thing?

No, you can replace individual gauges. Occasionally people sell them when they have upgraded to a certified engine monitor as I did a few months ago.

[wiseng]

Looked into replacing the existing edm-700 with certified unit.  Too expensive for my taste.  The can has been sent to Air parts of Lockhaven to repair the OP gauge.