Gonna need to pull my Alpha outdrive, no water flow.Thinking its clogged

[crazy charlie]

Im transported home for the season.Twin 5.0 mercruisers with alpha one drives 1988.
Serviced water pump on stbd drive preseason.Only put a few hours this season with no issues with cooling so I am sure water pump service went well. My slip is muddy at low tide and after idling with drives 3/4 raised ,water flow to p.steering cooler stopped and engine temp raised .Hooked up muffs in my yard yesterday and same issue .Pressure washed intake screens on drive. Water exiting thru prop hub.My guess is water tube in the top of water pump is clogged with mud.Will find out when I pull the drive next week.I also pulled ps cooler hose at the stat and put garden hose in to reverse water flow thinking possible ps cooler was clogged but that didn't seem to be the case.Will keep posted. Anyone want to take a guess where the clog is? I have not had a bad impeller in over 20 years but it wouldn't be a 1st. Charlie

 

[Chris1956]

Charlie, I have had the water passage under the waterpump in the OD, nearly clog with barnacles. A lot of Alphas have removeable gratings for water intake. You can pull 'em off and take a look.

 

[Scott Danforth]

if the tube clogged, it most likely took out the water pump impeller

 

[Lou C]

My Cobra used to have the water intake screen just like the Johnny/Rude outboards, because it is moored in salt water, I had barnacles constantly growing on that thing. One year I split the drive pulled that screen out and never reinstalled it, I just rod out the holes a few times each season and haven't had any running hot problems in a long time. The holes on a Cobra are big enough that I can look inside with an inspection camera and see if there is anything else growing in there and then rod it out with a coat hanger wire. My brother had a 2020 Chapparal with the Merc 4.5/Alpha for about 3 seasons, and he had it go into guardian mode due to running hot (I guess that's what it's called) and we had to do the same thing, tilt up the drive and rod out the holes.
Thinking back when I split the drive, there were barnacles growing up above the water intakes. If you do that, I'd consider painting the inside of the water passage with Trilux II.
Do you get a lot of growth where you are?
The last 2 years it has been less here, it used to be really bad, either that or the paint got better, I can't tell lol. You're on the South Shore of LI, correct? I'm up on the North Shore....

 

[crazy charlie]

My Cobra used to have the water intake screen just like the Johnny/Rude outboards, because it is moored in salt water, I had barnacles constantly growing on that thing. One year I split the drive pulled that screen out and never reinstalled it, I just rod out the holes a few times each season and haven't had any running hot problems in a long time. The holes on a Cobra are big enough that I can look inside with an inspection camera and see if there is anything else growing in there and then rod it out with a coat hanger wire. My brother had a 2020 Chapparal with the Merc 4.5/Alpha for about 3 seasons, and he had it go into guardian mode due to running hot (I guess that's what it's called) and we had to do the same thing, tilt up the drive and rod out the holes.
Thinking back when I split the drive, there were barnacles growing up above the water intakes. If you do that, I'd consider painting the inside of the water passage with Trilux II.
Do you get a lot of growth where you are?
The last 2 years it has been less here, it used to be really bad, either that or the paint got better, I can't tell lol. You're on the South Shore of LI, correct? I'm up on the North Shore....

Yep plenty of fouling but I use several coats of trilux aerosol into the intake screens of the drive prior to launch. Usually no barnacles in there but who knows, it only takes a few big ones to make trouble.Im going with the mud theory for now till I pull the drive.Charlie