robertinmaine
Member
- Joined
- Jun 21, 2006
- RO Number
- 21904
- Messages
- 5
I have an issue that I have been perplexed with for an entire season …
I bought a boat that was overheating on the port engine when I sea trailed it – on first diagnosis the raw water impeller broke up and went through the system. We reversed flushed the system but the same over heat issue appeared.
The marina worked on it for months (in there busy season) – since I refused to take the boat with an over heat issue. It was a brand new rebuilt motor and I feared a cracked block. Then I got a call she was all set … I was told it was a defective new raw water impeller – so they re-replaced it (second one).
I drove the boat for an hour and saw with my own eyes that it was fixed – no over heat issue – saw it on the gage and felt the risers.
The very next season it was back to the exact same issue.
Here is what I've attempted since.
Thinking that impeller might be damaged again – I had it professionally replaced. Didn't fix it. I pulled the heat exchanger and cleaned it like it was going to a military inspection– it was fairly clean anyway. Didn't help at all. Replaced both risers. Didn't help at all. Replaced the antifreeze. Nothing.
I noticed the spark plug wires were a bit rusty inside the caps– they are next on my list anyway – but doubt it will fix the over heat issue.
On the gage:
The temp gauge will stay between 140 and 165 ALL day at idle and under about 1600 RPM's she climbs a little. Anything over 1600 RPM's and the needle keeps climbing – I don't let it go to the next mark (200) –and back off the throttle and she comes right back to normal temp. If I want to cool it faster I put it in neutral and rev the engine – cools right off. I know the gage is correct because I can feel the heat and I had someone shoot it with infrared.
What do I look at next ? Could it be the transmission?
Engine is a 454 Merc (closed cooling system – rear mount) – Velvet Drive Transmission.
Signed perplexed.
I bought a boat that was overheating on the port engine when I sea trailed it – on first diagnosis the raw water impeller broke up and went through the system. We reversed flushed the system but the same over heat issue appeared.
The marina worked on it for months (in there busy season) – since I refused to take the boat with an over heat issue. It was a brand new rebuilt motor and I feared a cracked block. Then I got a call she was all set … I was told it was a defective new raw water impeller – so they re-replaced it (second one).
I drove the boat for an hour and saw with my own eyes that it was fixed – no over heat issue – saw it on the gage and felt the risers.
The very next season it was back to the exact same issue.
Here is what I've attempted since.
Thinking that impeller might be damaged again – I had it professionally replaced. Didn't fix it. I pulled the heat exchanger and cleaned it like it was going to a military inspection– it was fairly clean anyway. Didn't help at all. Replaced both risers. Didn't help at all. Replaced the antifreeze. Nothing.
I noticed the spark plug wires were a bit rusty inside the caps– they are next on my list anyway – but doubt it will fix the over heat issue.
On the gage:
The temp gauge will stay between 140 and 165 ALL day at idle and under about 1600 RPM's she climbs a little. Anything over 1600 RPM's and the needle keeps climbing – I don't let it go to the next mark (200) –and back off the throttle and she comes right back to normal temp. If I want to cool it faster I put it in neutral and rev the engine – cools right off. I know the gage is correct because I can feel the heat and I had someone shoot it with infrared.
What do I look at next ? Could it be the transmission?
Engine is a 454 Merc (closed cooling system – rear mount) – Velvet Drive Transmission.
Signed perplexed.