1986 yamaha gearbox issue

Joined
Dec 26, 2016
Messages
6
I have a 40 HP, 1986 Yamaha ELJ (2 cycle, 3 cylinder) motor. In fall, found water in gear case oil. After searching for replacements which are available, I decided to try to replace the drive shaft and prop shaft seals. Following the recommendations of Dangar Marine and the precautions of the "hack method," I was able to remove and replace the seals. I did a pressure test using home materials after putting the unit back together and inflated to 15 PSA. Pressure was maintained above 10PSI for 3 minutes, and was 6PSI at 8 min. I wonder what the standards for satisfactory pressure test are? thanks. Peter, east end NY
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
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47,307
you should be able to hold pressure for days.
 

robert graham

Admiral
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Apr 16, 2009
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6,908
I believe there are accepted specifications for pressure testing lower units and the length of time for a leak down....maybe research this more....
 

boscoe99

Lieutenant Commander
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Aug 22, 2013
Messages
1,785
The Yamaha pressure test specification is for the lower unit to hold rated pressure for ten (10) seconds. Your unit appears to be just fine.
 

Mohawkmtrs

Chief Petty Officer
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Jan 13, 2010
Messages
561
Mercruiser (I know) procedure is:

Pressurize for 7-10 psi, observe gauge for 5 min.

Rotate d/s, p/s, mo e shift rod while pressurized to check for leaks.

Pressurize to 15-16 psi, observe for 10-15 min.

Rotate d/s...etc.

If pressure drop is noted, immerse in water (or use soap/water), re-pressurize housing and check for air bubbles.
 

racerone

Supreme Mariner
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Dec 28, 2013
Messages
36,048
I normally test 12 hrs or more.-----Do not like to see a pressure drop.-------Testing for 10 seconds, not me.
 
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