lower unit - water in oil

sailor bob

Recruit
Joined
Nov 12, 2008
Messages
4
I have a '99, Yamaha T9.9 EXHX outboard.

At the end of the '07 season, I noticed a slight amount of water in the lower unit oil. I had a mechanic replace all the seals before the beginning of the season. The mechanic that helped me last year talked of a tool to pressurize the lower unit and determine the source of the water leak into the lower unit. He didn't use this tool to confirm that the repair was successful. Is anyone familiar with this tool? Does anyone know what pressures are safe to test at with such an tool? There's nothing mentioned in my Clymer Yamaha Outboard Shop Manual.

Last week I pulled the boat and discovered that I had water and about a teaspoon of oil in the lower unit.
I've drained the water and oil, flushed the lower unit with oil, and removed the lower unit for repair. Does anyone know where I might find this seal pressure tester tool or a good Yamaha mechanic in the Kansas City area?

Thanks for your assistance.
Bob
 

BaileysBoat

Senior Chief Petty Officer
Joined
Sep 29, 2008
Messages
716
Re: lower unit - water in oil

Bob,

Yamaha wants the lower unit to hold 10 psi. Yamaha service tool YB-35956-A.
 

sailor bob

Recruit
Joined
Nov 12, 2008
Messages
4
Re: lower unit - water in oil

Thanks for the information.

I did find the following information in the Troubleshooting and Testing section of my Clymer Manual for the engine.

Slowly apply pressure with the pressure tester. Push, pull and turn all shafts while observing the pressure gauge. Stop increasing pressure when it reaches approximately 14.5 psi.

If the gearcase does not hold this pressure for at least 10 seconds, remove the gearcase. Submerge the gearcase, with pressure applied, to locate the leak . Replace the seal and/or seal surface at the location where bubbles appear.

Where can I purchase the pressure test tool you identified? Or do I need to try and fab something on my own with parts from the local hardware store?

Thanks in advance for any and all help in this matter.

Bob
 

triumphrick

Lieutenant Commander
Joined
Jun 26, 2008
Messages
1,737
Re: lower unit - water in oil

I have used a rented radiator pressure tester and made an adapter aftrer removing the lu oil drain plug to match the thread pattern. Most Advance and Auto zones have these tools.
 

mike64

Lieutenant Junior Grade
Joined
Apr 10, 2008
Messages
1,042
Re: lower unit - water in oil

I asked about changing oil and testing my LU a couple months ago and got some good replies, including HighTest describing how he built a pressure tester for around $10 (store bought will run you about $100).

http://forums.iboats.com/showthread.php?t=273386
 

sailor bob

Recruit
Joined
Nov 12, 2008
Messages
4
Re: lower unit - water in oil

Thanks again to everyone who replied. I read through the above referenced thread and found the information extremely helpful.

I have one of the pressure pumps that are used to fill the lower unit with oil. I wasn't sure this would pressurize enough. I'll use the fitting with my tire pump and incorporate a tee so I can use my old refrigeration gauges to measure the pressure. I'm looking forward to identifying the source of the leak and replacing the failed seal and sealing surface in lieu of replacing all the seals.

Cheers,
Bob
 
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