ken66770 Posted July 2, 2017 Report Share Posted July 2, 2017 During a local flight we discovered oil running down the front of the instrument panel of our 1974 Mooney M20C. There is enough to be obvious and to drip on the carpet. It appears to be coming from the front of the Tach/RPM gauge. I have pulled the cowling and can clearly see the back of the gauges but I can't really identify the source of the leak.The vacuum source inoperative light also just came on, which I assume indicates a bad Vacuum pump. Can the Vacuum pump and the oil leaking from the panel be connected? I can't get into an A&P for at least a week. Does anyone have any ideas about what could be happening from the symptoms I have described? Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted July 2, 2017 Report Share Posted July 2, 2017 A bad seal on the tach drive can force oil down the tach cable. It could be slinging it out onto the vacuum pump drive and ruin the pump. Or it could be something else. Quote Link to comment Share on other sites More sharing options...
neilpilot Posted July 2, 2017 Report Share Posted July 2, 2017 Do you have a mechanical oil pressure gauge? I had a leak in that area once on my 64E. Turns out the tubing connector behind the oil pressure gauge was left loose after an avionics tech worked on my transponder. Quote Link to comment Share on other sites More sharing options...
Guest Posted July 2, 2017 Report Share Posted July 2, 2017 Through the oil door you may be able to see the vacuum pump drive coupling. If you can see it, turn the prop by hand to see if the coupling is turning the pump. If it's sheared the engine end will turn but the pump end will not. Your oil leak from the tachometer be the drive seal in the engine as noted. You can un do the cable nut on the tachometer and see if oil pours from the cable. It is normally greased so nothing should come out of it. Clarence Quote Link to comment Share on other sites More sharing options...
ken66770 Posted July 2, 2017 Author Report Share Posted July 2, 2017 3 hours ago, neilpilot said: Do you have a mechanical oil pressure gauge? I had a leak in that area once on my 64E. Turns out the tubing connector behind the oil pressure gauge was left loose after an avionics tech worked on my transponder. Indeed, a mechanical gauge AND a new transponder just installed. It looks like the leak has stopped after I tightened the connector. The Tach is located directly under the oil pressure gauge the oil dripping from above evidently made it appear that oil was coming from the tach. It looks like the vacuum pump failure is just a coincidence. Thanks to all that responded. 3 Quote Link to comment Share on other sites More sharing options...
cliffy Posted July 4, 2017 Report Share Posted July 4, 2017 MGB=Lucas=work work work work work (ref: Blazing Saddles :-) Quote Link to comment Share on other sites More sharing options...
Cyril Gibb Posted July 4, 2017 Report Share Posted July 4, 2017 12 hours ago, cliffy said: MGB=Lucas=work work work work work (ref: Blazing Saddles :-) Lucas "Prince of Darkness" could usually be vanquished by familiarity under the bonnet (hood) with a simple set of spanners (wrenches) in the boot (trunk) with the aid of a torch (flashlight) at night. Quote Link to comment Share on other sites More sharing options...
cliffy Posted July 4, 2017 Report Share Posted July 4, 2017 And a large box of spare parts with a lifetime of 30 mins from a dilapidated building somewhere in the deep forest of the north country, or, maybe the bogs. I hear the hounds coming :-) Quote Link to comment Share on other sites More sharing options...
DonMuncy Posted July 4, 2017 Report Share Posted July 4, 2017 1 hour ago, Cyril Gibb said: Lucas "Prince of Darkness" could usually be vanquished by familiarity under the bonnet (hood) with a simple set of spanners (wrenches) in the boot (trunk) with the aid of a torch (flashlight) at night. I especially liked Lucas starters. They jammed in the flywheel frequently, but Lucas recognized the problem and extended the starter shaft out the rear with a squared end, so you could turn it and "unjam" it. I carried an appropriate sized spanner in the trunk of my Lotus Elan. When it jammed, I could lay on the ground, reach up by feel and fix it in about 15 seconds. Quote Link to comment Share on other sites More sharing options...
Jerry 5TJ Posted July 4, 2017 Report Share Posted July 4, 2017 Just as well Lucas did not make magnetos for Lycomings. Quote Link to comment Share on other sites More sharing options...
Oldguy Posted July 4, 2017 Report Share Posted July 4, 2017 Experienced with the Lucas electrics - '56 Austin Healey 100-4, '56 MGA, '66 AH Sprite, '76 MGB, and currently '67 MGB (1/3 done). Lucas refrigerators - the reason behind warm beer. Quote Link to comment Share on other sites More sharing options...
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