500dollar744ti
Senior Chief Petty Officer
- Joined
- Jul 23, 2012
- Messages
- 691
At the start of the season I like to take my boat out for a test trip before I go on any journeys or invite people out. Yesterday I put in at the local ramp and went about 10 miles down river at moderate speed. I began to smell a 'popcorn' burning smell for lack of better words, I slowed to idle and shut down the engine.
I found the port side rubber exhaust couplers smoking but only that side. I let it cool until I could touch both risers and then restarted. The port side immediately heated up like a stove burner while the starboard side was just warm. I knew that I wasn't going to be able to limp back.
In preparation for the season, I had replaced my drive bellows, water pump impeller, shift cable, and one of the exhaust couplers on the port side. I idled the engine with water hooked up in my driveway and made sure I had adequate exhaust water flow and there was no overheating. I thought for sure it was something I did with the port exhaust tube so I wanted to take it back apart.
Thanks to what I've learned on here, I know that water could come into the boat if I remove the exhaust elbow so I took my oar and rowed my 23ft cuddy to the shoreline and beached it.
I took the exhaust elbow out and tried to clear any rust/debris from the riser and I removed the flapper in case it was getting stuck. I put it back together and pushed back into the water deep enough that I could run the engine. I ran the engine at idle for a while and both risers stayed at normal temps.
I went back out and headed back to the ramp. Everything was good at cruising speed for about 15 mins then the temp started to rise to 160 so I came back to idle and shut it down. I waited a couple minutes and started it back up, the temp came back down and I continued on. Five minutes passed and it started to rise again so I shut it down and did the same thing. I made it back to the ramp and loaded up the boat and brought it home.
My guess is that the manifolds and risers are clogged with rust that dislodged over the winter. I think the water is pushing rust into the ports until it clogs, then when I shut it down, the rust subsides and it can flow again for a while.
My repair will be to replace both manifolds and risers, does this sound like the appropriate course of action? Also, I've heard the exhaust flappers cause more harm than good, is that true? Should I leave the flappers out on both sides or move to replace them?
Thanks in advance for your help.
I found the port side rubber exhaust couplers smoking but only that side. I let it cool until I could touch both risers and then restarted. The port side immediately heated up like a stove burner while the starboard side was just warm. I knew that I wasn't going to be able to limp back.
In preparation for the season, I had replaced my drive bellows, water pump impeller, shift cable, and one of the exhaust couplers on the port side. I idled the engine with water hooked up in my driveway and made sure I had adequate exhaust water flow and there was no overheating. I thought for sure it was something I did with the port exhaust tube so I wanted to take it back apart.
Thanks to what I've learned on here, I know that water could come into the boat if I remove the exhaust elbow so I took my oar and rowed my 23ft cuddy to the shoreline and beached it.
I took the exhaust elbow out and tried to clear any rust/debris from the riser and I removed the flapper in case it was getting stuck. I put it back together and pushed back into the water deep enough that I could run the engine. I ran the engine at idle for a while and both risers stayed at normal temps.
I went back out and headed back to the ramp. Everything was good at cruising speed for about 15 mins then the temp started to rise to 160 so I came back to idle and shut it down. I waited a couple minutes and started it back up, the temp came back down and I continued on. Five minutes passed and it started to rise again so I shut it down and did the same thing. I made it back to the ramp and loaded up the boat and brought it home.
My guess is that the manifolds and risers are clogged with rust that dislodged over the winter. I think the water is pushing rust into the ports until it clogs, then when I shut it down, the rust subsides and it can flow again for a while.
My repair will be to replace both manifolds and risers, does this sound like the appropriate course of action? Also, I've heard the exhaust flappers cause more harm than good, is that true? Should I leave the flappers out on both sides or move to replace them?
Thanks in advance for your help.