OK to wash lower unit?

[HotTommy]

I am replacing the water pump on my 1996 Force 90 HP outboard motor. This picture shows how dirty the area around the pump is.

I'd like to wash the area aggressively before I remove the old water pump, but I'm concerned there may be a way for water to get down into parts that shouldn't see water. So, my question is whether or not it is OK to aggressively wash this lower unit before I remove the water pump?

 

[foodfisher]

Re: OK to wash lower unit?

IMHO, if water can get to where it shouldn't, it's already there. Go for it.

 

[jerryjerry05]

Re: OK to wash lower unit?

Yup like food says wash, even pressure wash.
Then if you really want???/ Paint it,2-3 coats of cheap spray paint.
Since it's that corroded???
Make sure you clean the threads and bolts with a thread chaser and clean them out and grease them when you reassemble.

 

[Frank Acampora]

Re: OK to wash lower unit?

Aw, C'mon! Think about it: The whole lower unit is under water when the boat is at rest!

That is a Mercury lower unit and pump. The threads on the pump are coated with a thread-lock compound and are metric--either 10 or 11 mm. They will come out easily. Changing that impeller is a piece of cake. Clean the pump and bolts--use a wire brush if necessary, then go for it. The hard work (removing the lower unit) is already done.

Just be careful to replace the shift rod exactly as it was. If you have moved the rod and are off by a spline or two, it will not shift correctly.

 

[HotTommy]

Re: OK to wash lower unit?

Thanks to all for the advice. I did clean it before replacing the entire water pump assembly. I'll see if it runs (and shifts correctly) tomorrow.

P.S. to Fleet Admiral Acampora - You likely know far more about these matters than me. But aren't there parts of the motor that are both under water and sealed to prevent water intrusion? I'm not experienced enough to know what parts are and are not routinely exposed to water. That's why I asked.

 

[Frank Acampora]

Re: OK to wash lower unit?

I was just surprised that no one else mentioned it.

The gearcase is a sealed unit with water tight seals everywhere a shaft passes through. When at rest, the whole lower unit is under water and when running, the pump is above water. However, as you can see in your own photo, exhaust gases and cooling water pass through right behind the pump. Sometimes there is a gasket there and sometimes not.

At ant rate, the pump can be washed and scrubbed if necessary: The shaft seal is below the bottom stainless plate of the pump. As I said, you have already done the difficult work, Replacing the impeller will be easy. I have never had a lower unit of this design have bolts seized. BUT: That doesn't mean you can get ham-handed and careless. If a bolt does feel like it is stuck, don't twist it off. Use some of the common methods mentioned in the forums to fee it.

 

[HotTommy]

Re: OK to wash lower unit?

As long as we're discussing water pumps, I have a related question.

My first effort to test run the engine came to a premature halt this morning when priming the fuel line revealed a significant leak in one of the carburetors. I removed the carb and diagnosed the problem as a sticking/maladjusted float valve. With everything put back together, it fired up on the third crank. Other than a faster than expected idle speed (sounded like 1500 RPM to me), everything seemed ok. Water was coming from the exhaust in the center of the propeller, and from the small hose that runs from the top of the powerhead to the water temp gauge. However, I never saw water come from the hose on the aft side of the thermostat housing. Even after I ran the engine for about ten minutes at idle, the thermostat housing did not feel especially warm to the touch. Here's a photo of the engine running.

So, I didn't note any signs of water pump failure or overheating, but I am curious why no water came from the P-hose. Can anyone enlighten me?

 

[johnbottsr]

Re: OK to wash lower unit?

Not sure I am qualified to answer but from what I have read the water pumps are not self-priming and since you are running on ears no pee.
Try with the lower unit submerged to a point above the water pump.

 

[HotTommy]

Re: OK to wash lower unit?

The mystery is solved. A small clump of red clay deep inside the P-hose fitting was blocking the water flow. All is well now.

 

[belairbrian]

Re: OK to wash lower unit?

Not sure I am qualified to answer but from what I have read the water pumps are not self-priming and since you are running on ears no pee.
Try with the lower unit submerged to a point above the water pump.

You should still get water out the tell-tell / pee hose when running on the hose. The issue with running on a hose is it can't supply enough water for runs above idle.

 

[belairbrian]

Re: OK to wash lower unit?

Ain't spring great. I just cleaned a mud dauber out of my fire estenguisher nozzle.