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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 1977 mercruiser stern drive. it is over heating

Customer Question

I have a 1977 mercruiser stern drive. it is over heating after about 4or 5 minutes. I replaced the main water pump and the lower unit pump. It is still over heating I am try to follow the cooling system direction of flow, I think something is pluged. I took the large manifold elbow off and cleaned them out, as good as possible, it seem like water is flowing through them when I put water to them while there off. I took the main hose coming from the lower unit pump to the thermostat manifold and it appears to be getting plenty of water. Is there a diagram of the water flow so I can see if something is pluged. If I'm going in the wrong direction let me know
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.

Hi Gary, my name is Jason.

I have some questions back to you.

Is the boat running on a garden hose or is it in the water?

Do you have an IR temp gun to see what the temps are at the thermostat housing and exhaust manifolds and risers?

What is the history on this engine, when did it last cool correctly?

When you changed the impeller, did the old one come out in 1 piece, or was it missing pieces?

Did you change the thermostat yet?

Expert:  Jason replied 1 year ago.

Hi Gary. It looks like you read my response and logged off without replying back to me. The website did charge you to speak with me, was this something you still needed help with?

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