Have Boat Questions? Ask a Boat Repair Expert.
Hi John, my name is Jason.
All Mercruisers are cataloged by serial number. Can I start by getting that number.
Next, does it overheat at low speeds, high speeds or all speeds?
Are you still with me John?
Got the serial. Lets start with a water volume output test. Locate the output hose of the seawater pump. This will run from the pump to the thermostat housing. Disconnect the hose at the housing. If you have a bucket this will work best. Start the engine up, bring the rpms up to 1500. Aim the hose at a bucket for 10 seconds, and then at the end of those 10 seconds aim the hose away, and quickly shut the engine off. Let me know how much water you get approximately in gallons.
Got it. Wait for the engine to cool a bit. Do the same thing but this time snap the throttle in neutral a few times. Let me know if the water volume decreases or increases when you snap the throttle
What I meant was disconnecting the throttle cable from the engine, and then just touching the throttle linkage by hand and snapping the throttle. Chances are you have bravoitis but i'm just trying to confirm. When was the last time the bellows were changed on the boat?
Before I answer all those questions. If you hook the water line back up, and simply run it at idle, does it still overheat or does it run a stead 160F or so?
Good morning and sorry for the delay. When you replied last night I was already off to bed. As long as the engine isn't overheating at 1500 rpms then you can certainly run the engine without fear of harm. But if the engine is overheating at that rpm, then you would want to tow it, not drive it.
Good morning. Let me ask you another question here. Is the engine actually overheating? Did you take the engines temperature manually in order to rule out a bad gauge or sending unit giving a faulty reading?
Do you have enough room to pull the water line and also the fitting for the water line off of the inner transom plate?