rhanson Posted August 9, 2016 Report Share Posted August 9, 2016 My 912ULS oil pressure Guage sometimes is pegged, 100%. For takeoff it is normal, 30 - 70 psi. The A/P thinks that a sensor( horiz. Barrel) on the front of the engine can be easily replaced to correct the problem. Any ideas on cost, and correct diagnosis ? RH FYI SEZ AD Closed for 10 days; resurfacing. Link to comment Share on other sites More sharing options...
Roger Lee Posted August 9, 2016 Report Share Posted August 9, 2016 What causes the oil pressure sender to read excessively high is a poor ground and a bad sensor. The sensor is a fairly common cause. Tighten the 5 main grounding points and if it isn't fixed replace the sender for $40. Link to comment Share on other sites More sharing options...
Tom Baker Posted August 9, 2016 Report Share Posted August 9, 2016 My 912ULS oil pressure Guage sometimes is pegged, 100%. For takeoff it is normal, 30 - 70 psi. The A/P thinks that a sensor( horiz. Barrel) on the front of the engine can be easily replaced to correct the problem. Any ideas on cost, and correct diagnosis ? RH FYI SEZ AD Closed for 10 days; resurfacing. The VDO sensors work by varying the resistance from low resistance for low pressure to high resistance for high pressure. 180 ohms = about 145 PSI. Link to comment Share on other sites More sharing options...
Roger Lee Posted August 10, 2016 Report Share Posted August 10, 2016 "The VDO sensors work by varying the resistance" This is why a good solid ground is so important. As throttle and rpm change so does the resistance through the electrical system.. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted August 10, 2016 Report Share Posted August 10, 2016 My gauge has recently started wild swings (70psi to 10psi) again, and seems based on engine rpm. Last time I tightened the grounds and it was fixed. I will have to do that again, and if that doesn't do it I will get another sender. I was hoping I was done replacing senders when I moved it to the firewall...time will tell. Link to comment Share on other sites More sharing options...
Roger Lee Posted August 10, 2016 Report Share Posted August 10, 2016 Hi Andy, Big swings tend to be bad wire connections or a poor ground. Not usually the sensor. I had a fuel pressure swing a while back that would set the alarm off. Took me a while to find it. I knew it wasn't the real fuel pressure. I had done everything. What it finally was the spade connectors on the sender itself. They felt like they were on there nice and firm. I had pulled them off and slid them back on, but out of desperation I squeezed them with some pliers and problem solved. Sometimes it's the smallest thing. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted August 10, 2016 Report Share Posted August 10, 2016 Hi Andy, Big swings tend to be bad wire connections or a poor ground. Not usually the sensor. I had a fuel pressure swing a while back that would set the alarm off. Took me a while to find it. I knew it wasn't the real fuel pressure. I had done everything. What it finally was the spade connectors on the sender itself. They felt like they were on there nice and firm. I had pulled them off and slid them back on, but out of desperation I squeezed them with some pliers and problem solved. Sometimes it's the smallest thing. One of the things I did was pull the spade connectors off and re-seated them last time. I might need to use some pliers. It's hard to see in there which wire is the oil pressure sender wire though...any advice on picking the right wire so I don't have to just put the piers to them all? Link to comment Share on other sites More sharing options...
Anticept Posted August 10, 2016 Report Share Posted August 10, 2016 Put a dielectric on those connectors. Reduces oxidation quite a bit and doesn't risk shorting. DC-4 is a good one. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted August 10, 2016 Report Share Posted August 10, 2016 Put a dielectric on those connectors. Reduces oxidation quite a bit and doesn't risk shorting. DC-4 is a good one. Wilco, thanks. Link to comment Share on other sites More sharing options...
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