- Aug 25, 2008
- 1,819
- Boat Info
- 2006 320 V-Drives 6.2s, Bow Thruster, Generator, Raymarine C80, Radar, Fish Finder
- Engines
- 6.2 Horizons 320HP
I have a pair of 6.2 Fresh water cooled Horizon engines. 340 hours / 7 years old. 2 weeks ago I started to have a rough idle with one engine. The boat ran perfect before I went for a ride, but when I came home I had a very rough idle and needed to shut one engine down. I could get the engine re-started and as long as I kept the rpm's above 1,000 rpms, The vibration would smooth out and I could drive the boat. Once on plane all guages checked out; volts, temperature, fuel burn etc. Both engines were in sync.
I wasn't sure what was causing the rough idle, so I started with the basics. I changed spark plugs, cap & rotor, wires, AIC valve and fuel filters. My neighbors complained about the smell of fuel at startup and suggested that I probably had a stuck fuel injector. I also noticed a slight hydro lock sensation at start up and thought that a stuck fuel injector in the open position might be dumping fuel into one cylinder causing the hydra lock and rough idle and once it burned off and I picked up RPM’s the engine ran smoother. I did a pressure test of the fuel system expecting it to fail and it held pressure. At this point I was at a loss so I called Doc Ron DDS to pick his brain. After talking through my issues with Ron it occurred to me that I really need to figure out why I am having hydro lock issue at startup so I reluctantly decided to start pulling spark plugs to see if I could figure out what was going on.
Well the very first spark plug I pulled was wet with water not gas. So I pulled my exhaust risers thinking I had a bad gasket. After chipping away some of the carbon on one of the risers, I poked a hole through the wall. So obviously I need to replace all of my rises. My neighbor and good friend owns a marina that allows him to get me parts at dealer prices, so I hit him up for a favor. After he spoke to his parts guy he came back with the recommendation to replace both risers and the manifolds. I didn’t want to cut corners, so I agreed and told them to order 4 of everything. I am picking the parts up tomorrow. However, this is my rub. I started to re-think the exhaust configuration. The risers are cooled with raw salt water and they failed, however my manifolds are cooled with anti-freeze and as far as I know are still good. So now I am questioning if I really need to replace the manifolds or are they still ok?
Any thoughts?
I wasn't sure what was causing the rough idle, so I started with the basics. I changed spark plugs, cap & rotor, wires, AIC valve and fuel filters. My neighbors complained about the smell of fuel at startup and suggested that I probably had a stuck fuel injector. I also noticed a slight hydro lock sensation at start up and thought that a stuck fuel injector in the open position might be dumping fuel into one cylinder causing the hydra lock and rough idle and once it burned off and I picked up RPM’s the engine ran smoother. I did a pressure test of the fuel system expecting it to fail and it held pressure. At this point I was at a loss so I called Doc Ron DDS to pick his brain. After talking through my issues with Ron it occurred to me that I really need to figure out why I am having hydro lock issue at startup so I reluctantly decided to start pulling spark plugs to see if I could figure out what was going on.
Well the very first spark plug I pulled was wet with water not gas. So I pulled my exhaust risers thinking I had a bad gasket. After chipping away some of the carbon on one of the risers, I poked a hole through the wall. So obviously I need to replace all of my rises. My neighbor and good friend owns a marina that allows him to get me parts at dealer prices, so I hit him up for a favor. After he spoke to his parts guy he came back with the recommendation to replace both risers and the manifolds. I didn’t want to cut corners, so I agreed and told them to order 4 of everything. I am picking the parts up tomorrow. However, this is my rub. I started to re-think the exhaust configuration. The risers are cooled with raw salt water and they failed, however my manifolds are cooled with anti-freeze and as far as I know are still good. So now I am questioning if I really need to replace the manifolds or are they still ok?
Any thoughts?