Pressurizing the Crank Case

[cchildr84]

I have an 81 25 HP Evinrude, and I'm in the process of changing out all the lower unit seals and water pump, etc. I now have it all back together and look to re-attach to exhuast housing. I read some things stating to check the pressure or to pressurize the seals to check for leaks. My questions is this, should the pressure check be done before placing gear lube in the crankcase or after? Also, I've seen differing reports as to how much pressure to introduce. Any particular procedure to follow to check pressure, and how much pressure is to much.

 

[AlTn]

Re: Pressurizing the Crank Case

no lube in gearcase for test...manual calls for 3-6 psi..no leaks...16-18 psi..no leaks passes..then vacuum test 3-5 " of mercury..holds..15" of mercury..holds..all is well..fill with lube and bolt it on. That's what the book says, real world experience experience may differ.

 

[cchildr84]

Re: Pressurizing the Crank Case

no lube in gearcase for test...manual calls for 3-6 psi..no leaks...16-18 psi..no leaks passes..then vacuum test 3-5 " of mercury..holds..15" of mercury..holds..all is well..fill with lube and bolt it on. That's what the book says, real world experience experience may differ.

Ok, that sounds simple enough. I figured I'd get a cheap bycycle pump for the pressure test, but what to I use for the vacuum test, and where can I get it.

 

[GA_Boater]

Re: Pressurizing the Crank Case

You can pick up a vacuum pump at an auto parts store. Sometimes called a vacuum brake bleeder. AutoZone carries this one for example: OEM/Vacuum pump (25136) | Vacuum Pump Brake Bleed Kit | AutoZone.com

 

[boobie]

Re: Pressurizing the Crank Case

When you pressure and vacuum test the lower unit make sure you run the moving parts through their cycles. Drive shaft, prop shaft and shift rod.

 

[cchildr84]

Re: Pressurizing the Crank Case

When you pressure and vacuum test the lower unit make sure you run the moving parts through their cycles. Drive shaft, prop shaft and shift rod.

I didn't get your message in time prior to filling the unit with lube and remounting. But both pressure and vacuum tests were successful; no loss of pressure or vacuum in either test. And now that lube is in the unit and it's conected back to the rest of the motor everything is shifting fine and appears to be in working order. I have a few more parts I want to replace under the cowling hood before I start it, but hopefully it works out. Likely, I'll change the thermostat as well. This is a used motor, so I'm going through and replacing typical wear items. Thanks all for your help.