Hello all,
Found this forum while researching a recent cooling problem on my 1995 Mercury 2.5L Offshore 200hp outboard. Although I am sure the topic has been covered many times, I was unable to find my answers using the search.
Yesterday I was out on my boat. Temp was great at idle with no alarms, idled out for about 35 minutes. As I brought it up on plane, the constant steady alarm began to ring. One steady alarm - Beeeeeeeeeeeeeeeep! Check my temp gauge and it is just up over 3/4 (usually it stays in the center). Ease back the throttle and the alarm stops, and temp comes back down to the center. Never heats back up at idle. I have great water flow out the back with a 2 month old impeller. Thinking it was a stuck thermostat, I pull both thermostats out of the top of the heads and try running motor without them in to rule them out. Still get same problem when I throttle up.
I called an uncle who has twin Merc 150's as he might have an idea and he mentions poppit's. I cannot identify these on my engine, even though he indicates to me that they should be between the top two plugs on each cylinder head. Instead I see a crows foot type piece holding a rubber plug with a wire on each side. One brown, one blue/brown which I assume is the temp sending units.
Are there poppit's on the engine somewhere? Does this sound like the problem, or can I assume possibly a faulty temp sender? Is there anything else I should be looking for? I plan on replacing the thermostats since I have them out, as well as the temp senders. Any direction and advice is greatly appreciated.
Regards,
-=Rick
Found this forum while researching a recent cooling problem on my 1995 Mercury 2.5L Offshore 200hp outboard. Although I am sure the topic has been covered many times, I was unable to find my answers using the search.
Yesterday I was out on my boat. Temp was great at idle with no alarms, idled out for about 35 minutes. As I brought it up on plane, the constant steady alarm began to ring. One steady alarm - Beeeeeeeeeeeeeeeep! Check my temp gauge and it is just up over 3/4 (usually it stays in the center). Ease back the throttle and the alarm stops, and temp comes back down to the center. Never heats back up at idle. I have great water flow out the back with a 2 month old impeller. Thinking it was a stuck thermostat, I pull both thermostats out of the top of the heads and try running motor without them in to rule them out. Still get same problem when I throttle up.
I called an uncle who has twin Merc 150's as he might have an idea and he mentions poppit's. I cannot identify these on my engine, even though he indicates to me that they should be between the top two plugs on each cylinder head. Instead I see a crows foot type piece holding a rubber plug with a wire on each side. One brown, one blue/brown which I assume is the temp sending units.
Are there poppit's on the engine somewhere? Does this sound like the problem, or can I assume possibly a faulty temp sender? Is there anything else I should be looking for? I plan on replacing the thermostats since I have them out, as well as the temp senders. Any direction and advice is greatly appreciated.
Regards,
-=Rick