sandpiper Posted October 19, 2011 Report Share Posted October 19, 2011 Yesterday evening, about half way through a pleasant sunset flight, my oil pressure started acting up. I have analog, not Dynon, and the pressure usually runs around 45 psi with some fluctuations but now it was on 70, then it whipped on up past 100 (redline) then came back down to normal. Then up again and down again. By the time I landed it was going over 130 which is the top reading. On the ground idling back to the hangar at 2000 RPM it was normal again. I've had issues twice before. The first was about a year ago when the pressure dropped to zero. Replacing the sender solved that. Shortly afterwards it started acting like it did last night and that was the wire hanging on the sender by a thread. Replacing the connector solved that. This time no such luck. Nothing obvious but I am suspecting a ground issue, not the sender. Before I start tearing everything apart I thought I would post here to see if any good ideas came up. Link to comment Share on other sites More sharing options...
Roger Lee Posted October 19, 2011 Report Share Posted October 19, 2011 Hi John, When they swing around and go real high or peg out then it is a ground or connection issue. Check the ground wires first. Link to comment Share on other sites More sharing options...
mocfly Posted October 19, 2011 Report Share Posted October 19, 2011 I would put money on the ground. If you read this forum long enough most electrical issue, at least when dealing woth analog gauges are due to geounding isaues. What I did to finally correct the grpunding issues on pur aircraft was to run a seperate ground wire 20ga from the back of the vdo directly to the engine. This was done on cht, oil temp and oil pressire. Bypassed the interior bus. Which performs marginal at best. The next was to replace the crimp connector at the sender. Scotchbrite the sender before re attatching the crimp connector. In order to do this you will need to remove and replace the pins on the db9 connector at the sender on each. I assure you if done right this grounding issue will not come back Link to comment Share on other sites More sharing options...
mocfly Posted October 19, 2011 Report Share Posted October 19, 2011 Sorry for the spelling, I rely to much on spell check and a keyboard larger than my iPhone Link to comment Share on other sites More sharing options...
sandpiper Posted October 20, 2011 Author Report Share Posted October 20, 2011 Thank you. I figured the grounding would be the issue. I'll post if I find anything. It might be that, after cleaning/tightening connections, that the problem will have gone away. Link to comment Share on other sites More sharing options...
sandpiper Posted October 22, 2011 Author Report Share Posted October 22, 2011 Cleaned up the connector at the sender and thought the problem was solved. However, on the test flight I had one excursion from the steady 48 psi it was showing up to 70 psi then it settled back down and stayed steady for the rest of the flight at about 48. I don't know about the Dynon set up but with analog there is such a jumble of wires behind the panel that I don't know where to start. Maybe mocfly has the right idea. Link to comment Share on other sites More sharing options...
Roger Lee Posted October 22, 2011 Report Share Posted October 22, 2011 Hi John, Might be time to just replace the sender. About $40 Link to comment Share on other sites More sharing options...
sandpiper Posted October 22, 2011 Author Report Share Posted October 22, 2011 Roger - I'm tempted since I have a spare. I ordered two last time. I think I will fly it a couple more times but that probably is just putting off doing what really needs to be done. These things don't get better by themselves Link to comment Share on other sites More sharing options...
Roger Lee Posted October 22, 2011 Report Share Posted October 22, 2011 Replacing the sender may be the only way to check things out. Might as well just do it and put that frustration to bed. Link to comment Share on other sites More sharing options...
Tom Baker Posted October 22, 2011 Report Share Posted October 22, 2011 You can test the sender on the bench with a compression tester and a couple fittings from the hardware store. Link to comment Share on other sites More sharing options...
mocfly Posted October 23, 2011 Report Share Posted October 23, 2011 Tom, You have a picture or a line schematic of your test rig? Chris Link to comment Share on other sites More sharing options...
Tom Baker Posted October 23, 2011 Report Share Posted October 23, 2011 Tom, You have a picture or a line schematic of your test rig? Chris It's just a female quick disconnect that plugs into the compression tester with a 1/4" to 1/8" pipe bushing. Screw the sender into the fitting and plug into the compression tester and you can dial the pressure up and down. I check the resistance per the attached chart. I have found bad spots in the middle of the normal range. Oil Pressure.doc Link to comment Share on other sites More sharing options...
Tad Olmsted Posted October 23, 2011 Report Share Posted October 23, 2011 Don't forget... The sender uses the oil pump housing as a ground. Don't use thread tape of any kind ever!!! This is a NPT thread and a small amount of Loctite 222 or 242 on the sender will do the trick. I highly recommend putting the sender on the fire wall. The vibrations from the engine causes these things to go out. If this is done, make D@&* sure the fitting that goes into the oil pump has the restrictor in it. If there is a falure from the pump to the remote sending unit, only a small amount of oil will be allowed to come out of the restrictor. As we all know, it only take 30-45 seconds for the oil pump to evacuate the entire oil capacity if there is a line falure. Heads up!!! Link to comment Share on other sites More sharing options...
mocfly Posted October 24, 2011 Report Share Posted October 24, 2011 Guys, When the sensor goes bad is it a binary failure? Reason for the question is that I took the plane out on Thursday and all was well with oil pressure. Went out Saturday morning to do about an hour of touch and goes and the pressure goes to the bottom peg then up slightly. I keep the oil level between 40% and full at all times. Temps were all in the green. I was waiting to get a replacement sender when one of the guys took the plane out today and reported that the gauges for his entire flight were steady and in the green the entire flight. Any thoughts? Link to comment Share on other sites More sharing options...
Roger Lee Posted October 24, 2011 Report Share Posted October 24, 2011 Hi Mocfly, If the oil level was full and the sender went to zero or really low then 99 times out of 100 it's a bad sender. Just replace it. Sandpiper, You already have a new sender and it's just as easy to pop that in and check it against the old one verses a bunch of testing as far as time goes. Link to comment Share on other sites More sharing options...
mocfly Posted October 24, 2011 Report Share Posted October 24, 2011 Roger, I'll call and get on on the road in the am. Who is a good source? I don't have it remotely installed and think this would be a good time to do the changeover. Would you happen to have a list of items and maybe install pictures to make this remote mount change? Link to comment Share on other sites More sharing options...
Roger Lee Posted October 24, 2011 Report Share Posted October 24, 2011 Mocfly, Lockwood has a little remote oil or fuel kit put together. Call them and get a kit sent out. It is an easy install. It is more or less two brass fittings, one for the sender and one to put in the case where the sender came out. Then hose and fire sleeve. An Adel clamp to mount it on the firewall. that's all. It is an approved FD mod. Link to comment Share on other sites More sharing options...
Tom Baker Posted October 24, 2011 Report Share Posted October 24, 2011 Sandpiper, You already have a new sender and it's just as easy to pop that in and check it against the old one verses a bunch of testing as far as time goes. Roger, I agree that replacing if you have one is quicker, because likely your going to need to replace it anyway. I like to put them on the tester to show the customer that there was a bad spot to ease their mind. Tom Link to comment Share on other sites More sharing options...
airhound Posted September 21, 2012 Report Share Posted September 21, 2012 Roger, I agree that replacing if you have one is quicker, because likely your going to need to replace it anyway. I like to put them on the tester to show the customer that there was a bad spot to ease their mind. Tom Tom, what kind and how do you test.........are you measuring ohms, or what? Link to comment Share on other sites More sharing options...
Tom Baker Posted September 21, 2012 Report Share Posted September 21, 2012 Tom, what kind and how do you test.........are you measuring ohms, or what? I use a compression tester to check it. You can run the pressure up and down while checking the resistance. Here is a chart for the VDO oil pressure sender. VDO 0 - 10 bar oil pressure sensor. Bar psi Resistance (Ohm's) 0 = 0 = 7.2 0.5 = 7 = 18.2 1 = 14.5 = 28.2 1.5 = 21.75 = 39.2 2 = 29 = 49.2 3 = 43.5 = 68.2 4 = 58 = 87.2 5 = 72.5 = 104.2 6 = 87 = 121.2 7 = 101.5 = 137.2 8 = 116 = 153.2 8.5 = 123 = 160.2 9 = 130.5 = 167.2 10 = 145 = 181.2 Link to comment Share on other sites More sharing options...
BMcCand - N248CT Posted October 10, 2012 Report Share Posted October 10, 2012 I have had another VDO sender fail at about 300hrs (600 TT now) That seems to be the MTBF for these things. This time, I had a spare in the airplane, and was able to replace it in the field. I just need to add a 17mm wrench to my portable tool kit. I already carry a 13mm to adjust throttle tension. If I put in the new Honeywell, do I need a new 1" gauge too? Link to comment Share on other sites More sharing options...
westcoastoz Posted October 25, 2012 Report Share Posted October 25, 2012 I have just completed a trip of about 15 hours and on the last sector, the oil pressure that has been consistantly sitting at about 3.8 bar, went up to around 5.2 bar and stayed there or close to it for the rest of the flight. After landing when I shut down the engine, the oil pressure indicated 1.7 bar instead of zero as per normal. Has anyone else had a similar experience and can anyone tell me whether this is an earthing problem or is the oil pressure sender on the way out? The oil pressure is not fluctuating wildly, it is just indicating higher than normal. (I have the Dynon D120 EMS) Thanks. Dave Link to comment Share on other sites More sharing options...
Roger Lee Posted October 25, 2012 Report Share Posted October 25, 2012 The sender is most likely on the way out. Give it another flight or two to make sure. If it goes real high it may be a ground wire issues. (earthing issue for the down under friends ) Link to comment Share on other sites More sharing options...
westcoastoz Posted October 25, 2012 Report Share Posted October 25, 2012 Thanks Roger...will check it out. Regards, Dave Link to comment Share on other sites More sharing options...
airhound Posted October 25, 2012 Report Share Posted October 25, 2012 Overhere Earthing is what happens when you touch that red thingy..... Link to comment Share on other sites More sharing options...
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