How to Vacuum Test an Outdrive

[rybad]

(89' OMC Cobra 5.7)<br /><br />I had one of my outdrives in the shop for some work, and they pressre and vac tested it. They mechanic told me to do the other drive by pumping in 15lbs. for two minutes (check for leaks), then he said to vac. 15lbs. for two minutes and check for leaks.<br /><br />My question is, what can I use to create the vacuum to 15lbs. I have a small hand pump, but it reads in INCHES. I dont see anything that reads vacuum in pounds. I'm not sure if there is a conversion for inches to pounds.<br /><br />Any help/advice is appreciated.

 

[Don S]

Re: How to Vacuum Test an Outdrive

He was talking about 15 "Inches" not lbs of vacuum. In reallity, you will be lucky to hold 8 or 9 inches of vac due to the input shaft seal. It's only designed to hold oil in the drive and they will usually leak vac over 8 or 9 inches.

 

[rybad]

Re: How to Vacuum Test an Outdrive

Don;<br /><br />So, I have a "Mityvac" hand vacuum pump. It will vac up to about 25". If I vac to 15" as the mechanic said, will I damage that input shaft seal, or are you saying it will simply start to suck air in. I think the drive is in good shape, I'm just tyring to make sure, but I don't want to damage anything just to verify.<br /><br />(or it 8" vac sufficient to verify all seals?)<br /><br />Thanks.