Water in lower unit

[87merc150]

I noticed that I had water in my lower unit so I replaced my impellar and the gaskets that are in the plastic housing. When I took the old impellar out I noticed that it was twisted in there counter clockwise. I thought it was wrong but I put the new one in the same counter clockwise way. Was that wrong?
This has not fixed my problem with water in the lower unit. What is my next step that I need to do so the oil does not look milky.
The motor is a 1987 Mercury 150 everything looks original.

 

[Buddaorf]

Re: Water in lower unit

Sounds like you need the lower unit rebuilt. I usually have water through the water pump gets by the main drive shaft and into the oil of the lower unit. Not usually from behind the prop. Hope this helps.

 

[Moody Blue]

Re: Water in lower unit

Driveshaft turns clockwise so the vanes of the impeller should point CCW. If you've installed it backwards, it will self correct once the engine starts.

As for water in the LU, there are several possible causes.
1) Lower waterpump driveshaft seals
2) prop shaft seal
3) shift shaft seal
4) drain plug gasket
5) vent plug gasket

I would start cheap and go from there. Replace the gaskets under the fill and vent screws first for a couple dollars.

Next would be to change out the shift shaft bushing/seal assy. About $15 for the part.

Next I would replace the two driveshaft seals and O-ring in the lower waterpump housing.

Last approach would be to have to replace the propshaft seal.

 

[87merc150]

Re: Water in lower unit

Thanks for the info. When I was changing the impellar I took the plastic housing all the way down to metal. After that do I have to remove the drive shaft. If so do I need a puller. Same for the shift shaft.

 

[87merc150]

Re: Water in lower unit

When you get water in your lower unit does your level go up so when you take your vent screw off water/oil comes out. My oil level has never gone up so does the oil leave and water takes it's place. I also don't have a leak coming from my drain plug so does that mean water also can't get in there.

 

[Chris1956]

Re: Water in lower unit

Drain the gearcase. Install a new waterpump base, Oring and gasket. Make sure the drivshaft is clean and lubed before you install the WP base. Install a new wearplate and gaskets and then a new impeller. Now fill the gearcase with marine gear lube, and reassemble.

Driveshaft will not come out w/o removing propshaft and gears.