Merc Heat Alarm on 50hp 4 stroke

[AK Jack]

Just found this site and I'm confident with all of the knowledge out there someone might have an answer or solution. Last year I hit a rock in shallow water at full throttle. I did some lower unit damage and had it replaced by a Merc dealership. Now comes the problem. If the motor is running at med. to high revs no alarm. If I idle down to it's lowest rpm's my heat alarm will sound off. I took the motor back to the place that did the work and they informed me that my pump was fine, couldn't find any problem with the module as well. I never had any problem before it went to the shop. I'm pulling my hair out. With any luck the Kenai will open up for king fishing in July and I would like to have a motor that doesn't wake the dead if it idles to low. Mechanic told me after the last go around that he was certain that no harm is being done to the motor, just a gremlin so to speak. Should I just disconnect the alarm wire? Thanx for all of the help in advance<br /><br /> AK Jack

 

[DJ]

Re: Merc Heat Alarm on 50hp 4 stroke

AK Jack,<br /><br />Do not disconnect that alarm, it's your only line of defense against catastrophic failure.<br /><br />Did the dealership actually drop the "new" lower unit and make sure the pump was OK? Something did not go together right. I would like to be standing there when they drop it again, or for the first time, and see what they see.<br /><br />You paid for a repair and it is not yet complete. You are not being too demanding.

 

[kev_alaska]

Re: Merc Heat Alarm on 50hp 4 stroke

Djohns is right, the dealer is not finished with your repair yet. When you are at low RPMs the impeller is naturally not pumping as much water, heat alarm. At higher RPMs the pump is pumping more water, no temperature alarm. Check the ends of the impeller and see if they still have the rounded shape. <br /><br />The Kenai is killing those of us who fish in the Susitna, I have never seen so many 35 horse boats in the big river.....Good Luck...<br /><br />Kevin