terry_thatcher
Terence Thatcher
I seek advice about my 4-108 which has always been reliable. I changed out the impeller, as advised, after over a year's layup. When I started up, there was no water coming out of the exhaust. But the raw water pump was pushing water out of the outlet (I pulled the hose and checked. Then I pulled the hose off the exhaust elbow, and no water was making it out of the heat exchanger. I put a hand pump in the exchanger to elbow hose and pumped--and lo, water started flowing. Some sort of airlock, I thought. We made an 80 mile run at cruising speed (1900 rpm) and the engine seemed to be running a little warmer than usual, but not dangerously warm.
So, we started for the Columbia Bar, in choppy seas, with the engine working hard and the boat being thrown around. After about an hour, the engine overheated dangerously and we sailed back to a marina, running the engine, with no water exiting the exhaust, for only 5-6 minutes to get to a dock and tie up. Next day, I pulled the heat exchanger out. There was a piece of old zinc rattling around in it, perhaps big enough to plug an inlet or outlet (raw water inlet on bottom of exchanger, outlet on top.) Otherwise, water flowed easily thru the exchanger. I removed the old zinc piece, put things back together and the engine, including the cooling, ran just fine, with proper temperature, for 7 hours of cruising under power as a test.
We crossed the bar and started beating into 20-25 knot northwesterly, engine off. We sailed for 12 hours, mostly on the starboard tack, and got tossed around pretty good. We then shifted to port tack in reduced wind. Engine intake is on port side of boat. As the wind died, we turned on the engine. NO WATER FROM THE EXHAUST. I went below and checked the raw water strainer--its water level was low, perhaps below the outflow. That has never happened before. It will typically fill the minute the seacock opens. So, I went to the raw water pump and took off the inlet hose from the strainer to the pump, and, lo, water poured out. Hooked things back up, turned on the engine, and it ran like a charm for 32 hours.
I think the initial overheating was caused by a heat exchanger plugged by the zinc. But I have no proof. Could the pump be weak? (Rebuilt pump maybe 300 hours ago.) But I have no good explanation for the stainer not automatically filling offshore after a rough 12 hours and no explanation for why it then refilled. (It is below the water line.) I did notice the inlet fitting was a little loose, but it has never leaked before. Since the events, I have checked the seacock and all hoses and pipes for blockages or collapse. All are good. I am going to replace the raw water strainer (Raritan) with a Forespar model.
So, I think things are probably ok now. My son and first mate, however, wants me to hire a mechanic to check things out. But what will he or she check? The engine is running fine, with proper temp and water in the exhaust. But I admit the events were disconcerting. So, I seek comments, suggestions, or any other advice you all might give. It was a strange combination of events and ruined a planned cruise. Thanks.
So, we started for the Columbia Bar, in choppy seas, with the engine working hard and the boat being thrown around. After about an hour, the engine overheated dangerously and we sailed back to a marina, running the engine, with no water exiting the exhaust, for only 5-6 minutes to get to a dock and tie up. Next day, I pulled the heat exchanger out. There was a piece of old zinc rattling around in it, perhaps big enough to plug an inlet or outlet (raw water inlet on bottom of exchanger, outlet on top.) Otherwise, water flowed easily thru the exchanger. I removed the old zinc piece, put things back together and the engine, including the cooling, ran just fine, with proper temperature, for 7 hours of cruising under power as a test.
We crossed the bar and started beating into 20-25 knot northwesterly, engine off. We sailed for 12 hours, mostly on the starboard tack, and got tossed around pretty good. We then shifted to port tack in reduced wind. Engine intake is on port side of boat. As the wind died, we turned on the engine. NO WATER FROM THE EXHAUST. I went below and checked the raw water strainer--its water level was low, perhaps below the outflow. That has never happened before. It will typically fill the minute the seacock opens. So, I went to the raw water pump and took off the inlet hose from the strainer to the pump, and, lo, water poured out. Hooked things back up, turned on the engine, and it ran like a charm for 32 hours.
I think the initial overheating was caused by a heat exchanger plugged by the zinc. But I have no proof. Could the pump be weak? (Rebuilt pump maybe 300 hours ago.) But I have no good explanation for the stainer not automatically filling offshore after a rough 12 hours and no explanation for why it then refilled. (It is below the water line.) I did notice the inlet fitting was a little loose, but it has never leaked before. Since the events, I have checked the seacock and all hoses and pipes for blockages or collapse. All are good. I am going to replace the raw water strainer (Raritan) with a Forespar model.
So, I think things are probably ok now. My son and first mate, however, wants me to hire a mechanic to check things out. But what will he or she check? The engine is running fine, with proper temp and water in the exhaust. But I admit the events were disconcerting. So, I seek comments, suggestions, or any other advice you all might give. It was a strange combination of events and ruined a planned cruise. Thanks.