UPDATE 5/20/2009
I purchased a waterpump rebuild kit for my boat. Last night I removed the gearcase and I am "reasonably sure" that I found the problem. It appears that the last time the impeller was replaced, the mechanic sandwiched 3 of the impeller blade tips with the stainless cup. Maybe the mech tightened the WP cover without twisting the drive shaft as you should??? I'll bet the first time the motor was fired after the impeller replacement, the blade tips were ripped off and have been there since, blocking full flow of water, and thus causing my WOT overheat.
See attached pictures.
I will lake test this weekend and hope for the best. I hope the two overheats that the motor suffered didn't harm anything!
ORIGINAL POST
It's been a while since I have posted to this forum. My last question dealt with purchasing a boat. Advice was much appreciated. I have since purchased a 1999 Hurricane Deck Boat with a Yamaha C115TLRX Pre-mix engine. I test drove the boat for about 45 minutes before I purchased and the boat ran flawlessly at all speeds.
Last weekend was the first run on my lake with the boat. Of course, my good luck, the alarm sounded after about 2 minutes of WOT running. Shutoff immediately and after about 5 minutes, alarm off and started back up. Ran at below 4K rpm for about 30 minutes, no problems. Tried WOT again, 5500 rpm, and again alarm sounded.
Motor runs beautifully, other than the possible overheat.
I have read many posts dealing with this same issue on this forum. Here's how I plan to approach the problem. Do these steps sound feasible???
1) Run the boat at idle, monitor temp of heads with infrared thermometer.
2) Run the boat at 3500 rpm, monitor temp.
3) Run boat at WOT, wait for alarm, monitor temp.
If heads are truly hot:
4) Pull poppet valve and clean with vinegar. Can I reuse gasket, if not, can I use "form a gasket"???
5) Pull thermostats, test and clean. Reuse gasket???
6) Pull gearcase, replace water pump, inspect water tube.
7) Pull heads, clean with vinegar, clean cylinder jackets, replace head gaskets.
If heads are NOT hot:
8) Check thermoswitches.
9) Replace battery. ( I had to charge battery before first outing, battery was totally dead. Would this engine sound alarm if voltage is too low???)
Any and all advice welcome and appreciated.
I purchased a waterpump rebuild kit for my boat. Last night I removed the gearcase and I am "reasonably sure" that I found the problem. It appears that the last time the impeller was replaced, the mechanic sandwiched 3 of the impeller blade tips with the stainless cup. Maybe the mech tightened the WP cover without twisting the drive shaft as you should??? I'll bet the first time the motor was fired after the impeller replacement, the blade tips were ripped off and have been there since, blocking full flow of water, and thus causing my WOT overheat.
See attached pictures.
I will lake test this weekend and hope for the best. I hope the two overheats that the motor suffered didn't harm anything!
ORIGINAL POST
It's been a while since I have posted to this forum. My last question dealt with purchasing a boat. Advice was much appreciated. I have since purchased a 1999 Hurricane Deck Boat with a Yamaha C115TLRX Pre-mix engine. I test drove the boat for about 45 minutes before I purchased and the boat ran flawlessly at all speeds.
Last weekend was the first run on my lake with the boat. Of course, my good luck, the alarm sounded after about 2 minutes of WOT running. Shutoff immediately and after about 5 minutes, alarm off and started back up. Ran at below 4K rpm for about 30 minutes, no problems. Tried WOT again, 5500 rpm, and again alarm sounded.
Motor runs beautifully, other than the possible overheat.
I have read many posts dealing with this same issue on this forum. Here's how I plan to approach the problem. Do these steps sound feasible???
1) Run the boat at idle, monitor temp of heads with infrared thermometer.
2) Run the boat at 3500 rpm, monitor temp.
3) Run boat at WOT, wait for alarm, monitor temp.
If heads are truly hot:
4) Pull poppet valve and clean with vinegar. Can I reuse gasket, if not, can I use "form a gasket"???
5) Pull thermostats, test and clean. Reuse gasket???
6) Pull gearcase, replace water pump, inspect water tube.
7) Pull heads, clean with vinegar, clean cylinder jackets, replace head gaskets.
If heads are NOT hot:
8) Check thermoswitches.
9) Replace battery. ( I had to charge battery before first outing, battery was totally dead. Would this engine sound alarm if voltage is too low???)
Any and all advice welcome and appreciated.
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