DIY LU pressure tester?

[likitvi]

Any ideas on how to make pressure tester for LU for DIY pressure testing?

I can get an oil fitting for the LU, and maybe demolish a ~30 USD bicycle foot pump with pressure gauge, I think its hose would fit directly with the fitting. Are there any fittings that would allow installing a bike air valve or such into an air hose?

 

[jakedaawg]

Re: DIY LU pressure tester?

You can google search Lower Unit Pressure Tester and there are a couple links for homemade jobs. My question is why not spend the $133 and get a stevens s-34 that will last a lifetime?

 

[matt167]

Re: DIY LU pressure tester?

Yup, bike pump and a gear lube fitting works just fine.

 

[phillnjack2]

Re: DIY LU pressure tester?

What is the pressure you want to test it at ?
plus what are you going to use as a release valve ? tyre type valve and valve key ?
i.e valve left in fitting and then use valve key to release pressure when taking it off.

What exactly are you trying to achieve ?

cycle pumps will put upto around 100psi if you want them to, this would be enough to crack a gearbox, especially if its a Yamaha !!!


phill

 

[matt167]

Re: DIY LU pressure tester?

With my tester ( above ). I test at 12 PSI. The gauge is pretty well marked below 20 PSI. My LU leaked and I just wanted to see what seals needed replacing, so I knew that it was an auto drain. But for the purpose of a pressure test when I know it should hold pressure, a T fitting in the line with a plastic ball valve will work to release pressure... Currently the investment for my tester is around $27. $10 for a new gear lube pump, and $17 for the bike pump, and the bike pump schrader valve fitting unscrews, and the gear lube fitting fits right in that hose

 

[phillnjack2]

Re: DIY LU pressure tester?

I see, all sounds pretty good.
so what pressure would you think the gearbox runs at when on the boat ?
at least you have a gearbox oil pump and a bike pump to use as well as a gearbox pressure tester all for the small sum of money.
sounds good to me, multi purpose and cheap.


phill

 

[matt167]

Re: DIY LU pressure tester?

Doubt the pressure is over 10-15 PSI when on the boat.. I had read to test between 10 and 15 PSI, so that's why I split the difference and test at 12 PSI

 

[phillnjack2]

Re: DIY LU pressure tester?

sounds good.
I would think about 2psi when running on the boat as gearbox would be running very cool if enough of the right oil is also in there.


phill

 

[likitvi]

Re: DIY LU pressure tester?

Yup, just to get a little over pressure into the unit, and hold it there. Certainly should never exceed 30psi. I hope the gauge is accurate enough on those cheap bike pumps to not exceed 30psi actual when it shows 10 or 15, or so.

There is a minor leak in the LU, oil is very thick and milk coffee colored after season. I hope it will reveal is it a shaft seal or just the either of the drain plug fittings leaking.

 

[matt167]

Re: DIY LU pressure tester?

Gauge on mine is accurate. I plugged it into a valve stem on my truck and compared the gauge to a known accurate tire gauge and it was on the money.. If it was not accurate, I'd have split a tee in the line that I could fit my 0-15 PSI fuel pressure gauge line onto. Still not a bad idea

 

[classiccat]

Re: DIY LU pressure tester?

I use a Mityvac...allows you to test both pressure / vacuum.



It doesn't qualify as DIY but it's relatively inexpensive.

 

[clanton]

Re: DIY LU pressure tester?

Should hold 15 psi for a few minutes and 15 psi vacuum for a few minutes.

 

[likitvi]

Re: DIY LU pressure tester?

Something like that Mityvac would work excellently, but so far I haven't found one here for under 100 USD. And ordering from US would quickly cost the same adding freight and tax.

 

[minuteman62-64]

Re: DIY LU pressure tester?

Here's mine - combo for both pressure and vacuum: http://forums.iboats.com/mercury-mariner-outboards/lower-unit-adventures-580305.html

 

[metriccrescentwrench]

Re: DIY LU pressure tester?

Should hold 15 psi for a few minutes and 15 psi vacuum for a few minutes.

You meant to say 15 inches of mercury of vacuum.

Anyway, I finally found the procedure in my OMC service manual. It says to apply 3 - 6 psi and verify that the gearcase is holding pressure. If it's good at that pressure go to 16 - 18 psi. Then if all is good apply 3 - 5 in. of mercury of vacuum and verify that it holds. If so then go up to 15 inches of mercury of vacuum.

 

[kfa4303]

Re: DIY LU pressure tester?

Any ideas on how to make pressure tester for LU for DIY pressure testing?

I can get an oil fitting for the LU, and maybe demolish a ~30 USD bicycle foot pump with pressure gauge, I think its hose would fit directly with the fitting. Are there any fittings that would allow installing a bike air valve or such into an air hose?

+1. That'll work. Several other folks have made similar gizmos. I love anything DIY.