tarheelebbtide
Petty Officer 3rd Class
- Joined
- Jul 4, 2008
- Messages
- 94
1992 Mercruiser 350 Mag 5.7L recently rebuilt (last year) with all new peripherals (water pump, weber 4bbl carb, starter), and Alpha One sterndrive. It has thru hull stainless exhaust with the y-pipe for the below water exhaust capped off in the engine compartment. Let me first say that I'm probably overly paranoid about the boat since the rebuild so both of these may be nothing.
Yesterday when out for about 4 hours, I kept thinking I noticed the slight smell of gasoline a good bit of the time. Of course this is a carbeurated engine so I'm not sure if it is running rich and exhausting unburned fuel or if it's natural (particularly with the above water exhaust) to smell just a bit of fuel (and it isn't much of an odor at all). The second concern is that if at idle through a no wake zone for a long period of time, the boat will run warm (about 175 on the guage). If i notch it up to a fast idle, it comes right back down within 15-20 secs and hovers at the correct 150. It also holds 150 consistently when out on the open water. It will have a small and brief spike if I run it hard (4000 RPM or better) and come back down to a fast idle, but I assume that's natural as it quickly rectifies itself. The impeller is less than a year old as is the engine recirculation pump. It's almost as if the impeller doesn't spin fast enough at idle to circulate a good water flow but at just above idle it's fine. Could this be a symptom of the rebuild and boring (as in the engine naturally running warmer due to larger pistons and thinner water jacket)? Anyhow, I might just be paranoid about both issues as it ran like a champ all day and will blow just about anyone nearby out of the water, but I'd rather be safe than sorry.
Just FYI, it's only used in fresh water.
Yesterday when out for about 4 hours, I kept thinking I noticed the slight smell of gasoline a good bit of the time. Of course this is a carbeurated engine so I'm not sure if it is running rich and exhausting unburned fuel or if it's natural (particularly with the above water exhaust) to smell just a bit of fuel (and it isn't much of an odor at all). The second concern is that if at idle through a no wake zone for a long period of time, the boat will run warm (about 175 on the guage). If i notch it up to a fast idle, it comes right back down within 15-20 secs and hovers at the correct 150. It also holds 150 consistently when out on the open water. It will have a small and brief spike if I run it hard (4000 RPM or better) and come back down to a fast idle, but I assume that's natural as it quickly rectifies itself. The impeller is less than a year old as is the engine recirculation pump. It's almost as if the impeller doesn't spin fast enough at idle to circulate a good water flow but at just above idle it's fine. Could this be a symptom of the rebuild and boring (as in the engine naturally running warmer due to larger pistons and thinner water jacket)? Anyhow, I might just be paranoid about both issues as it ran like a champ all day and will blow just about anyone nearby out of the water, but I'd rather be safe than sorry.
Just FYI, it's only used in fresh water.
