StevenL757 Posted June 29, 2017 Report Share Posted June 29, 2017 On 5/21/2017 at 10:06 PM, wpbarnar said: '97 Encore with electric standby vacuum pump located in the avionics bay. The standby pump recently failed during preflight run up checks. Disassembled the pump and found oil in the pump which had caused stuck vanes in the rotor. The inside of the pump was oil wet. Where did the oil come from? The primary engine driven is a dry vacuum pump. Apparently there is enough oil in the line from the manifold where the two pumps connect to the standby pump to cause problems. Any ideas on the source of the oil? I typically only operate the standby pump during preflight run up checks only. How could engine oil get past the primary pump, not foul it and contaminate the standby vacuum system? Bill Bill, good guidance here from many so far, so can't add much more. If you want or need to replace your standby vac pump, I will offer you mine from my cockpit upgrade last year. It was tested successfully, and had been bagged up since, and is in pristine condition. Same model as yours. Let me know if interested and we can work it out. Steve Quote Link to comment Share on other sites More sharing options...
wpbarnar Posted June 29, 2017 Author Report Share Posted June 29, 2017 9 hours ago, Greg_D said: Thanks for the follow up Bill. It looks like I'm going to have to do the same procedure. How long do you estimate it would take without moving the seat and side panels? If I did it again, 3 to 4 hrs. Doing it for the first time 4+ hrs. Probably the most difficult part was removing the old hose from the manifold under the glare shield. It is difficult to reach and see. Practice on the spring clamp with your tool of choice on the standby vacuum pump end before tackling the hard to get to one. Remove the left rear seat back and screws holding the side panel so it can pulled away at its top and back edge. Remove the carpeted side panel in the baggage compartment. It comes out easy with the side panel loose. From that point I could kneel in the baggage area and reach and see the two difficult spots when pulling the new hose in place. There is a vertical piece of the fuselage tube frame located at the end of the passenger compartment and beginning of the baggage area. The hose is routed between that piece of tubing and fuselage skin which is a tight fit. The other tricky spot is just forward of that area. The hose transitions down and forward through a hole in a flange of the fuselage. As I feed the new hose through that hole, my helper pulled on the old hose over the top of the panel. That is a long pull, but we did not encounter any resistance from that point forward. Bill 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted June 30, 2017 Report Share Posted June 30, 2017 Great follow-up, Bill! best regards, -a- Quote Link to comment Share on other sites More sharing options...
Turbo KG Posted November 1, 2019 Report Share Posted November 1, 2019 while this is an older thread...having found this problem on a m20R and talking to mooney about it. there is a service bulletin out- M20-317 the hose is in fact deteriorating and causing the oil type fluid to ruin the pump. the bulletin has you replace the yellow tube from the firewall to the pump in the tail hope this helps others searching for help with this problem KG Quote Link to comment Share on other sites More sharing options...
carusoam Posted November 2, 2019 Report Share Posted November 2, 2019 Welcome aboard KG. That PVC tube challenge affected a bunch of Mooneys... Anytime PVC gets used in planes... it has a limited life, and finds a way to fail... In this case it killed a few vac pumps... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
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