Last time out, I noticed on the way in my boat was running hot. It is a mercruiser, v8, 350 with Alpha outdrive. It is raw water cooled, I use it in salt water.
Boat had been running great all year, no problems at all.
At first I thought it was because of barnacles and other build up at the intake holes on the outdrive. So, got back to the boat and scraped it all down, got rid of a lot of stuff.
With engine cooled off, I started it up. No luck, it slowly climbed up and past the normal temp wich is always about 150 F. It was just under 200 last time running, and I shut it down before it got to that temp again.
I noticed, though, that in idle, if I reved up the engine a little, it brings down the temp a little, almost imediately.
I went and felt cooling hoses at the engine and here's what I found. The 2 hoses that connect direclty to the thermostat housing were cool (these also connect to the exhaust manifolds, I believe), and it felt like there was running water thru them.
The other hoses that go to the water pump were hot, but I also felt water running thru them I believe.
Other details - there is no leaking or screaching or any signs that the water pump is bad (at least the one on the engine itself). The belt is tight and turning the water pump just fine.
Now, I believe there is another Impeller water pump in the outdrive. This has not been changed in a long time, but again I see no signs that water isn't running thru the system.
The boats in the water, so its hard to see if water is actually coming out thru the exhaust holes. Its a pain to take the boat out, or I would hook it up to the ear muffs and run water thu this way, to at least see if water is in fact running up and thru the engine, then out the exhaust like it should.
Since my first guess was wrong I believe (clogged water intakes at the outdrive), my next guess is a sticking thermostat, or bad thermostat. I really don't think its the acutal waterpump - its not wobbling or doing anything like its bad. And, I can feel water running thru the hoses by pinching them.
Any help from here???
Final question, can I take off the thermostat housing while the boat is in the water? This is on the higher end of the engine, well above the water line. I just didn't want water gushing in from the outside!
Boat had been running great all year, no problems at all.
At first I thought it was because of barnacles and other build up at the intake holes on the outdrive. So, got back to the boat and scraped it all down, got rid of a lot of stuff.
With engine cooled off, I started it up. No luck, it slowly climbed up and past the normal temp wich is always about 150 F. It was just under 200 last time running, and I shut it down before it got to that temp again.
I noticed, though, that in idle, if I reved up the engine a little, it brings down the temp a little, almost imediately.
I went and felt cooling hoses at the engine and here's what I found. The 2 hoses that connect direclty to the thermostat housing were cool (these also connect to the exhaust manifolds, I believe), and it felt like there was running water thru them.
The other hoses that go to the water pump were hot, but I also felt water running thru them I believe.
Other details - there is no leaking or screaching or any signs that the water pump is bad (at least the one on the engine itself). The belt is tight and turning the water pump just fine.
Now, I believe there is another Impeller water pump in the outdrive. This has not been changed in a long time, but again I see no signs that water isn't running thru the system.
The boats in the water, so its hard to see if water is actually coming out thru the exhaust holes. Its a pain to take the boat out, or I would hook it up to the ear muffs and run water thu this way, to at least see if water is in fact running up and thru the engine, then out the exhaust like it should.
Since my first guess was wrong I believe (clogged water intakes at the outdrive), my next guess is a sticking thermostat, or bad thermostat. I really don't think its the acutal waterpump - its not wobbling or doing anything like its bad. And, I can feel water running thru the hoses by pinching them.
Any help from here???
Final question, can I take off the thermostat housing while the boat is in the water? This is on the higher end of the engine, well above the water line. I just didn't want water gushing in from the outside!