Pressure testing

[Wotknot]

Could/would someone explain the proper way to pressure test (in detail) an outdrive? thanks

 

[muc]

Re: Pressure testing

I like to pump up to 4-5 psi and than turn all the shafts and wiggle the shifter while watching the gauge, if it will hold pressure for 3-5 mins. I will than go to 15 psi and turn and wiggle again. Have found some prop shaft seals that will hold at 15 psi but not 5 psi. I think it’s because the 15 psi pressure will push the lip of the seal against the shaft and stop the leak.

 

[Don S]

Re: Pressure testing

Drain the gear lube, put all the plugs back in except for one. Adapt a hand pressure pump to the remaining hole and pump it up to around 15 psi and check for leaks. It should hold pressure without dropping more than 1 psi in 3 minutes.<br />You can check for leaks using soapy water sprayed on all the seals and connections. Then do the same with vacuum. You will only get about 8 or 9 in of vac because of the input shaft seal.<br />If you had said what kind of drive you had, you might have received some better detail.

 

[tommays]

Re: Pressure testing

a seal that may not leak under pressure may be able to leak under suction<br /><br /> when the drive gets hot the oil builds up pressure and when it cools it builds up a vacume and draws in water from any weak seal<br /><br />it is the reason the merc remote tank is so good it allows the oil a place to expand and contract as temp changes<br /><br />tommays

 

[cmyers_uk]

Re: Pressure testing

Don't want to hijack the thread but why is there a difference between pressure testing and vacuum testing. My small brain assumed they would both fail if there was a leak?

 

[Don S]

Re: Pressure testing

Chris<br />Most prop shafts, and some vertical shaft designs (Mercruiser) have 2 seals installed in opposite directions. The inside seal is designed to keep the gear lube in, the outer seal is set to keep the water out.<br />As an example, the input shaft seal on many drives is a single lipped seal set to keep oil in. When water gets in the bellows, water will get pulled into the drive when it cools down as the seal will not stop liquids from the opposite direction.

 

[cmyers_uk]

Re: Pressure testing

Thanks Tommays and Don it makes perfect sense now its amazing how little I know. I had done the vacuum test but now I need to do the pressure test. Its onto ebay to find the right tool!<br /><br />Enjoy Thanksgiving<br /><br />Regards<br />Chris

 

[KaGee]

Re: Pressure testing

This is a rig I made up. I have it set up to pressure check my engine and manifold. Just change the fitting to fit your drive. You can rob a fitting off of a oil pump kit used in filling the drive.<br /><br />

 

[Wotknot]

Re: Pressure testing

I bought a little "Mighty Vac" hand-type vacuum tester at Wally World a year or so ago. I guess I could use that by adapting it to the drive. It's out in my tool box in the garage but I think it'll pump up to about 15 psi or so. I assume you can pressurise and also do the vacuum test at the same place, i.e the vent screw on the side of an Alpha Gen II ?

 

[Bondo]

Re: Pressure testing

I assume you can pressurise and also do the vacuum test at the same place, i.e the vent screw on the side of an Alpha Gen II

Ayuh.......<br />Either the Vent, or Fill screw will work........<br /><br />BTW, It's a 3/8ths X 16tpi.......<br />Either robbing the connector off your oil fill,<br />Or drill a hole through a 3/8ths X 16tpi(standard 3/8s Course Thread) bolt.......

 

[Wotknot]

Re: Pressure testing

Ahhhhhhh, ya done answered my next question even before asking it........thanks Bondo.

 

[Don S]

Re: Pressure testing

Bondo at work. <br /><br />

 

[Wotknot]

Re: Pressure testing

Just came back in from looking for a 3/8 x 16 bolt. Found it. While in the garage I looked at the Wally World vacuum tester I referred to earlier. Gauge only reads in Hg. So guess I'll rig up a contraction like Kagee's.......unless Bondo with his super magical powers can give me a hg/psi conversion chart....

 

[Don S]

Re: Pressure testing

Hg and PSI or 2 completely different things. hg is the measurment in inches of vacuum, psi is the measurement for pressure. <br />When doing the vacuum test, just use the numbers on the vacuum gauge or the vacuum side of a dual purpose gauge.

 

[Bondo]

Re: Pressure testing

Ayuh,<br /><br />My Crystal Ball told me you were going to ask What the threads are in those Holes....................

 

[lakelivin]

Re: Pressure testing

Y'all have shown several hand built pressure testers. What about the vac tester? Is that something that needs to be purchased rather than something that can be easily rigged?

 

[Wotknot]

Re: Pressure testing

I'd think you would just put the fitting that connects to your outdrive on the other end/side of the diaphragm. Then it'll be on the vacuum/sucking side of the diaphragm rather than the pressure/blowing side of it.

 

[Don S]

Re: Pressure testing

Many people use the Mityvac tester found at almost every Auto parts stores, Sears, even Walmart has them.<br /><br />

 

[Wotknot]

Re: Pressure testing

Don seems to have a pic of everything. Rumor has it he's even got a pic of his 124 year old great, great grandmother......

 

[KaGee]

Re: Pressure testing

Lake, <br />Just replace the foot pump with a vaccum pump like Don pictured. I'm using a combo guage on the rig.