question about pressure testing lower unit

[55evinrude]

Hello everyone! I am going to pressure test my lower unit tomorrow on my 1955 evinrude fastwin. how much psi should i test to 15? and how long should i leave it under pressure?
and one more question is if the pressure does drop how can I find out which seal is leaking, My guess is soapy water? thanks

Nathan

 

[AlTn]

Re: question about pressure testing lower unit

I don't know the shop procedure, but here's what I did....pumped it to 6 psi...10 minute wait..ok...pumped to 12 psi..wouldn't hold..used oatley fluid for air testing plumbing installs < HD has it, soapy water should work as well >...found leaks at 3 screws at the gearcase halves seam as well as the vent screw...tightened those...pumped up to 12 psi...let it sit for an hour, no change in pressure...mounted the LU and no water entry in ~ 1 hour of use...1971 25 hp. Evinrude

 

[55evinrude]

Re: question about pressure testing lower unit

ok thanks AlTn!

Nathan

 

[Daviet]

Re: question about pressure testing lower unit

I usually pump them up to 12-15 PSI and submerge in water.
Make sure to rotate the drive/prop shaft while it is submerged.

 

[boobie]

Re: question about pressure testing lower unit

Also shift it, as it could be a shift rod seal.

 

[55evinrude]

Re: question about pressure testing lower unit

I did everything you guys said. and it held pressure and didn't leak! thank god. thanks for the help guys

Nathan

 

[HighTrim]

Re: question about pressure testing lower unit

Just so you know the more pressure you put on the seals the more you help them. Be sure to run a low psi test as well.

On these older gearcases, I dont pressure test them. If they;re leaking, they all get re sealed.

 

[55evinrude]

Re: question about pressure testing lower unit

Just so you know the more pressure you put on the seals the more you help them. Be sure to run a low psi test as well.

On these older gearcases, I dont pressure test them. If they;re leaking, they all get re sealed.

after I pressure tested it I filled it with gear oil and put it in a bucket of water left it for a couple days, turned the drive shaft no leaks. only way to 100% know if there leaking is to use it i guess.

Nathan

 

[AlTn]

Re: question about pressure testing lower unit

yeah....just crack the drain screw the first few times you use it to check for water intrusion

 

[Cap'n Chaos]

Re: question about pressure testing lower unit

Not trying to hijack, just trying to learn... what are you guys using for testing?

 

[55evinrude]

Re: question about pressure testing lower unit

Not trying to hijack, just trying to learn... what are you guys using for testing?

What i use is a gauge with a "T" fitting, one end goes to the gauge, one to the piece of clear hose (i believe it's 1/4") which goes into a metal fitting that screws into the lower unit drain plug. and on the side of the "T" fitting is any attachment for a bicycle pump...... so you pump it up to 15psi and check to see if pressure drops on the gauge.

Nathan

 

[HighTrim]

Re: question about pressure testing lower unit

Yeah I made my own out of a bicycle tire pump and the fitting from a gearcase oil pump.

You can buy the tool, but it's not cheap.

http://www.stevensinstrument.com/gearcase.htm

 

[AlTn]

Re: question about pressure testing lower unit

fatz posted one made from a mityvac mv8255 and the hose from a lower unit fill pump from wally world..the 8255 you can use to pump up pressure or vaccum...it's in the $55 range and the lu fill pump to rob the hose and fitting from is ~ $10