Water in lower unit

[Cmac2008]

Picked up a mercury 800 yesterday... it has sat for a couple years. First I checked the lower Unit oil and when I took out the plug water came out. Prolly a 1/4 cup or so then nice clean oil started to come out. What does this mean? If seals are bad wouldn't my oil be milky in color? Any thoughts?

 

[merc850]

The oil and water have separated after sitting so long, was there any rust in the water? The seals might be bad; the washers under the fill/drain screws might be bad or missing - there is also a seal at the shift shaft or the driveshaft is pitted and lets water in. Remove the water pump base (remove the flush screw first if so equipped) and check the seals and the DS. If you drain the oil and refill it with a gear lube pump you can pressurize it some and see where it leaks. Take the prop off and look at the propshaft seal area to check for leaks. I would just reseal it with new parts and gaskets. The shiftshaft bushing with the seal in it should be removed carefully so as not to pull the shaft out of the cam.

 

[Cmac2008]

That makes total sense...No rust in water and oil was very clean. I would like to get ahead and replace all the seals. Is there a kit you can buy? While I'm in there. Do u just replace the impeller or all pieces associated with the water pump? What else would u recommend paying some attention to on this motor? Going to do a compression test tomorrow and swap out the plugs

 

[merc850]

A Mercury dealer should have all the parts if you have the Ser. Nr. If the water pump is not melted or the stainless parts damaged all you need is the impeller and gaskets. If that motor has been sitting in water for 20+ years I would pull the powerhead and check the upper shift shaft for corrosion, mine let go this summer and it's not an easy repair job.

 

[Cmac2008]

Supposedly the motor ran fine two years ago. I'm going to do a pressure test tomorrow on the lower. Along with a compression test. The head has never been cracked cause it still has the factory lead wire in one of the bolts. Now if that's a good thing or not you tell me... I got to do some work with the throttle box b4 I can try to start it but can I just short the solenoid to get it to crank for my compression test?

 

[Chris1956]

Sure, jumper the starter solenoid to crank her for the compression test.

 

[Cmac2008]

Ok my drain and vent screws have no washers on them. Is this just a fiber washer needed?

 

[Chris1956]

Merc makes paper gaskets, with some kind of treatment (red or green color) to them, for the gearcase plugs. I use them, but am not sold that they are absolutely necessary. Experience has shown that most gearcase leaks are from a bad driveshaft seal.