98 optimax 225 temp alarm

[comer0hb]

Have a pair of 98 optimax 225's on our boat- the starboard engine will send temp alarm occasionally. Engines have less than 450 hours & purchased the boat new.

Listen closely- this will only alarm during acceleration (under load) 3,000-3,500 rpm as the boat is trying to get up on plane- if the alarm sounds I can reduce the rpms then the alarm will clear then ease back into the throttle & the alarm does NOT come back on, then you can run as long as you like with out a alarm- THIS ONLY OCCURS WHEN GETTING THE BOAT UP ON PLANE!!!

Have had the Mercury dealer in my area on the boat 3 times with computer hooked up & the alarm going off & he said he was not getting any faults on his computer- did this several times- his advice was to replace the engines (NOT going to happen over a fault light)

We have replaced water pumps (2) times- thermostats & have swapped all the temp sensors from 1 motor to the other & fault stayed on the starboard side engine.

This is just a pain to deal with - boat runs fine & IS NOT OVERHEATING- It will do this 1 minute after starting.

If I put more power to the port engine than on the starboard- 9 times out of 10 I will not get the alarm.

Have spent lots of time & $$$$ trying to correct this problem but nothing seems to happen, so since the Mercury dealer with his laptop hooked up can't tell me what's causing the fault I am kind of lost & am hoping someone else has seen this problem & can give me some advice-

Any advice is greatly appreciated!!!!!!

[boats.net]

I have seen that once before but it was from a transducer mounted in front of motor disturbing water flow to engine. See if trimming motor up or down makes a difference if so may not have a clean flow of water to pickup screens on lower unit.

[comer0hb]

Thanks for the reply- will take a look- but haven't changed or added anything on the boat- transducer always been where it is located now- had boat since new & this problem started last summer, put new water pump in & continued with problem- then replaced thermostats & no alarms all fall & spring this year. it didn't do it again until just a few weeks ago- water temp up much more than in the fall & spring- I did order all 3 new temp sensors- going to replace them with new-

I have tried trimming engine up & down some- didn't seem to change anything- I will take another look at the bottom of the boat just to make sure something hasn't changed there.

Thanks again for the reply