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Green-light grayish gear oil

T

tinboatman

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Good evening everybody I’ve been out messing with my 7.5 Chrysler and it runs like a champ, I drained the gear oil tonight after about 4 hours on the outboard since I last changed it to see how the seals are in the lower unit. The color was mostly dark green, the color of the oil I put into it but I there was some gray tenting to it and oil that sept out of the vent plug hole was completely light gray. I’m wondering if this is normal, means water is leaking into my lower unit, or if the gray is just the old gear oil I replaced (Which was extremely black) mixed with the new stuff?
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ANY other color usually means water.
Sometimes if the motors just been ran and ran for a time then the oils changed,
there could be air mixed in the oil????
Did you use new seals for the drain/vent plugs?
The old plastic crush type don't always reseal.
I use Mercruiser(fiber) drain plug seals. 191832 $1.20[FONT=&quot][/FONT][FONT=&quot][COLOR=#009A00 !important][FONT=&quot][/FONT][/FONT][/COLOR]
 
I provided a pic of the oil it’s not metallic gray more of a really light gray. The outboard shifts very smoothly so I really don’t think I blew the lower unit up.
 
No you are okay in that way, but you might find there is a leak somewhere. These lower units are a bit touchy for repair. If you decide to change the seals, please do your homework. Almost every one I have repaired has been either damaged by water infiltration, or from improper shifting adjustment causing wear.
 
No you are okay in that way, but you might find there is a leak somewhere. These lower units are a bit touchy for repair. If you decide to change the seals, please do your homework. Almost every one I have repaired has been either damaged by water infiltration, or from improper shifting adjustment causing wear.
If this is a lower unit like you have, then any rust on the part number 42 which is a spring will cause it to lose tension and create big problems.
 

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Alright thanks for the info, I dropped the lower unit and took a peek at the driveshaft seal and it has a big crack in it so Im gonna start by replacing that. If that doesn’t fix it I’ll check out doing prop shaft seals.
 
Yes, that is most often the seal that fails, (other than the prop shaft). It has some pressure on it from the water pump.
 
I don’t have the tools to pressure test it right now, I already bought some new seals so I’m gonna go ahead and replace that driveshaft seal. If that doesn’t fix it I’ll probably go ahead and pressure test it.
 
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