looking for a P337 Rear vacuum relief valve

weebyf15 · #1 12-06-19, 04:50 PM

Hello guys, I have a 79 P337 that is not holding suction on the aft engine. On start up its fine but decays away after a few minutes of running. I suspect its the relief valve as the pump has been replaced. I was thinking someone may have removed all their vacuum gauges and may have the old aft relief valve they don't need. You can PM me or let me know if you have any ideas you wish to share.
Thanks Brad

frank.oconnor19 · #2 01-02-20, 12:42 PM

Did you get this figured out? Have you adjusted the relief valve?

weebyf15 · #3 02-03-20, 02:04 PM

Still not figured out but I have made multiple adjustments attempts and actually my mechanic tried two cleanings. I am having a used serviceable one shipped this week. I'll let you know.

frank.oconnor19 · #4 04-30-20, 03:40 PM

just curious, have you settled this? how?

weebyf15 · #5 05-16-20, 06:44 PM

Yes it is fixed; I had a faulty check valve in the vacuum manifold up under the co pilots feet area. Replaced manifold and fixed, but after burning about a grand with a new rear pump and regulator.

hharney · #6 05-16-20, 11:13 PM

Wow, is the maintenance shop just changing parts to see if that works? That can get really expensive, do they know Skymasters?

weebyf15 · #7 08-17-20, 06:29 PM

Nope; Skymaster experience up here in the Florida Panhandle is hard to find. I am open to any and all suggestions. Been through three Mechanics, all were frustrated with the complexity of the P337. I don't push them, I'm pretty laid back. They all just want to work on something that does not get a write up every time It flies (which is getting very uncommon). I'm trying to view this as a marathon not a sprint, but....... Frustrating.