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Lower unit pressure test question on 1990 8 HP Mercury lower unit

C

code1p36

Regular Contributor


While draining the lower unit oil I noticed a very small amount of lightercreamy oil at the very beginning then cleared up quickly and was the normaldark green color for the rest of the oil. Looking back in the jug it is still dark green so must not have beenmuch water in there if any at all? Idecided to run a pressure test but wanted to know the proper way to runit. I have read 7-12 PSI will work butfor how long? It is has been rock steadyat 12 PSI for 30 minutes and the only time it looses pressure is when I pullthe shift shaft very slightly towards the driveshaft. There is a small o-ring under the impellerplate which is releasing the air. I knowwhen the motor is running the shaft only moves vertically so should I replacethis o-ring? It looks good when I takethe plate off. Is there any more tests Ishould run or should I just replace the impeller and call it good since it isnot normal for that shaft to move horizontally?

I know that o-ring is cheap but I want to get this on the water soon.



Thanks.








 
I ignore pressure readings and swear by (and occasionally at) vacuum readings only. Why? If the seals leak oil out, the LU will continue to function normally, for surprisingly little oil is needed. But if the seals allow water to leak in, the resulting froth--a poor lubricant--will damage metal surfaces (especially the shafts where they run on the needle bearings). Then it's BIG $$$ time.

Jeff
 
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