1997 Force 15 hp Lower Unit oil color

[pecheux]

Good day,

Had lower unit oil leakage last fall and had the lower unit checked ... after pressure test turned out the lower filler plug gasket was broken. Dealer said this was the only place it leaked ... the gasket was replaced by a nylon type gasket.

Prior to leaving the dealer's place I ran the engine in his test tank for 10 minutes at close to Wot and then he checked the lower unit oil ... no water oil was perfect.

Then I ran the motor on the boat twice ... up to 6 hours trolling and probably ran 10 miles at WOT.

Curious as I am I dropped the lower unit oil ... and it there was grayish streaks in the oil which I beleve means there was some water mixed with the oil.

As I took the vent plug out I saw that the gasket (force type) was ripped so I replaced that one with a nylon gasket just like the bottom refill plug had, and filled with new oil. Will test on the river by wednesday.

My question is: Where else could water come from that would not show on a pressure test ??

Thank you,

Pecheux

PS: Also may I ask: which grade gasoline would produce the smoothest idling on a 2 cycle outboard ? regular or High-test ??

 

[WillyBWright]

Re: 1997 Force 15 hp Lower Unit oil color

Pressure tests are next to useless when it comes to a unit that's years old. If water got in there, that's a failure and no pressure test is needed to tell you that it needs to be resealed. The problem with pressure tests is that they don't test conditions created by the water pump. If water got in there, there is a leak. End of story. Reseal it and reseal the whole thing.

Use only Regular gas.

 

[pecheux]

Re: 1997 Force 15 hp Lower Unit oil color

WillyBWright,

According to your recommendation I do presume I am right about the grey streaks withing the oil ??? right ??

I will run it one more time with those new nylon gaskets and drop the oil to double check .. just in case.

Then is there are any oil color changes ... all seals will be changed.

Thank you

 

[skibug]

Re: 1997 Force 15 hp Lower Unit oil color

Yep, pull the lower unit and look at the water pump base gaskets etc... Common place for water intrusion.

 

[pecheux]

Re: 1997 Force 15 hp Lower Unit oil color

Skibug

I beleve I am getting minor water infiltration since the oil went grayish (or greenish) after 8 hours of usage with a combination of trolling and Wot for a distance of 10 miles or so.

If the water pump gasket leaks then perhaps I could get away for a total seals overhaul ???

But then How would I know which one leaks ??

Thanks

 

[pecheux]

Re: 1997 Force 15 hp Lower Unit oil color

WillyBWright:

Changed those lower unit filler and vent plugs gaskets for nylon ones and took the boat on the river for another run which lasted 4 or 5 hours of mixed trolling and WOT withing approx 8 to 10 miles total distance.

Dropped the oil again ... this time no gray streaks but the oil itself went from clear brown (new) to a light olive greenish color and is still as oily as new.

This is new to me, may I have your expertise on the greenish color ?

Thank you,

 

[skibug]

Re: 1997 Force 15 hp Lower Unit oil color

If the oil looks milky, then water is getting in there and you will soon have bigger problems.

Your best bet is to just order a complete lower unit seal kit. It will come with all the seals and gaskets in the lower unit. Replace all these and you should be good to go. It's not that expensive and is pretty simple to replace all the seals in the lower unit.

Here is a breakdown of your lower unit just for your reference.

The seal kit looks to be about $30 for your motor.

 

[pecheux]

Re: 1997 Force 15 hp Lower Unit oil color

Skibug:

Thank you, I appreciate the drawing.

Cheers

Pecheux (Acadian slang for fisherman)

 

[skibug]

Re: 1997 Force 15 hp Lower Unit oil color

No problem,

You can go here and look at complete drawings:

www.mercruiserparts.com

Here is your lower unit with parts labled.

http://www.mercruiserparts.com/Show...inbr=1695&bnbr=15&bdesc=GEAR+HOUSING+ASSEMBLY