Dan in Alaska
New member
Hi, folks! I'm a new guy, here, referred over from another forum. I'm hoping you can help me.
I have twin 2007 Yamaha F225s, and one of them is running hot. I have engine data displayed on my Raymarine A68. Until recently, both engines ran approximately the same temp and fuel burn numbers. I hit a wrist-sized stick and caught both lower units. There was no physical damage done that I can see – no prop damage or external lower unit damage – not even scuffed paint. It was after the stick event, though, that I noticed that one engine now runs about 40-50 degrees hotter than the other one.
The Raymarine displayed 230 degrees on the hot engine, while the other one still ran in the low 180’s. The Yamaha tach/monitor gauges never alarmed or put the engine into limp mode. When I back off the throttles and let the engine idle, it cools down in a couple of minutes.
I took off the protective water intake screens on the lower unit, to inspect – no debris.
I replaced the water pump – no change, still ran hot.
I replaced both thermostats – no change.
I swapped the temperature sensors between the motors, figuring if the sensor was bad, the high temp numbers would follow the sensor. They didn’t – no change.
I flush the motors regularly, anyway, but I went ahead and flushed them with Salt Away – no change.
After a few more trips, checking to see if any of my repairs fixed the problem, I noticed the “hot” engine was not running a little rougher. At idle, the engine runs with much more vibration and noise than the other engine. I also noticed that the “hot” engine is now burning about 2-gals more per hour than the other engine at cruising speeds (4000-4300rpm). Whatever the problem is, it seems to be getting worse.
Time for professional help! I took the boat to a Yamaha shop, and they said they couldn’t find anything wrong with it. They tested the Yamaha gauge, and it does alarm as it should, so the mechanic wasn’t fully convinced that the engine was actually running hot. I asked them to do a compression check – it passed. They also did a leak-down test – it passed. The mechanic said the only thing telling me that the engine was hot, was an aftermarket display, and he wasn’t interested in chasing the problem further.
I took it to another Yamaha mechanic. He checked the poppet valve, and said it was working correctly. He checked the spark plugs, and bumped up the idle a little bit. He said he really didn’t find anything wrong, but after adjusting the idle the engine ran smoother.
The mechanics can’t seem to reproduce the problem in the shop, so I ran the boat again yesterday and took some video to take to the mechanic tomorrow. The one engine continues to run hot; it was up to 210 degrees in less than 5 minutes. After it gets hot, it idles rough and has a noticeable knocking sound. It sounds like it’s missing. The engine was also very slow to turn over and re-start.
I don’t think this is a cooling system issue. The motor pees just fine, and the discharge water is not scalding hot.
Any ideas?
I have twin 2007 Yamaha F225s, and one of them is running hot. I have engine data displayed on my Raymarine A68. Until recently, both engines ran approximately the same temp and fuel burn numbers. I hit a wrist-sized stick and caught both lower units. There was no physical damage done that I can see – no prop damage or external lower unit damage – not even scuffed paint. It was after the stick event, though, that I noticed that one engine now runs about 40-50 degrees hotter than the other one.
The Raymarine displayed 230 degrees on the hot engine, while the other one still ran in the low 180’s. The Yamaha tach/monitor gauges never alarmed or put the engine into limp mode. When I back off the throttles and let the engine idle, it cools down in a couple of minutes.
I took off the protective water intake screens on the lower unit, to inspect – no debris.
I replaced the water pump – no change, still ran hot.
I replaced both thermostats – no change.
I swapped the temperature sensors between the motors, figuring if the sensor was bad, the high temp numbers would follow the sensor. They didn’t – no change.
I flush the motors regularly, anyway, but I went ahead and flushed them with Salt Away – no change.
After a few more trips, checking to see if any of my repairs fixed the problem, I noticed the “hot” engine was not running a little rougher. At idle, the engine runs with much more vibration and noise than the other engine. I also noticed that the “hot” engine is now burning about 2-gals more per hour than the other engine at cruising speeds (4000-4300rpm). Whatever the problem is, it seems to be getting worse.
Time for professional help! I took the boat to a Yamaha shop, and they said they couldn’t find anything wrong with it. They tested the Yamaha gauge, and it does alarm as it should, so the mechanic wasn’t fully convinced that the engine was actually running hot. I asked them to do a compression check – it passed. They also did a leak-down test – it passed. The mechanic said the only thing telling me that the engine was hot, was an aftermarket display, and he wasn’t interested in chasing the problem further.
I took it to another Yamaha mechanic. He checked the poppet valve, and said it was working correctly. He checked the spark plugs, and bumped up the idle a little bit. He said he really didn’t find anything wrong, but after adjusting the idle the engine ran smoother.
The mechanics can’t seem to reproduce the problem in the shop, so I ran the boat again yesterday and took some video to take to the mechanic tomorrow. The one engine continues to run hot; it was up to 210 degrees in less than 5 minutes. After it gets hot, it idles rough and has a noticeable knocking sound. It sounds like it’s missing. The engine was also very slow to turn over and re-start.
I don’t think this is a cooling system issue. The motor pees just fine, and the discharge water is not scalding hot.
Any ideas?