[marty53]

I've been trolling the forums here for two weeks trying to find a resolution to my problem but still haven't found an answer specific to my problem. I would greatly appreciate any suggestions people here have.

A little background: 2 weeks ago I took the boat out for the first time and it was running perfectly, as it always has. Then, when I took it up to about 4500 RPM's, the alarm buzzer on the control box went off-- constant tone for overheat. The control is a brand new this year new style commander 2000 box with the warm up lever. I immediately shut the motor off, waited about 10 minutes and fired it up again, still buzzing.

I idled back to the dock, pulled the boat out and went home. In my driveway I fired the boat up on muffs (about a half hour later) and no buzzer/alarm. I then searched iboats for answers and immediately found out my first thing to do was change out the impeller/water pump. I bought an entire water pump kit with housing and replaced it this week. Running on muffs in the driveway the pisser tell-tale was shooting a TON of water out, what a difference the new impeller made.

Naturally, I think my problem is solved, so last night I took the boat out again, starts right up, no buzzer even at WOT. Then after about 15 minutes the buzzer goes off again, but this time it varies between a loud constant buzz and a dying cow kind of whine that made me thing right away that I either have a bad oil warning module (that control the oil and overheat alarms) or a bad buzzer in my NEW control box. I took the cowl off, jiggled the overheat sensor wire on the block in idle and the buzzer shut off. Back to cruising as usual, then about a half hour later it goes off again but it a little more whiney and unstable sounding. The water temp of the tell-tale was luke warm - cool at best, and I could rest my hand on top of the block for about 5-10 seconds-- so I'm pretty sure i'm not actually overheating. By the way, the oil injection is definitely working and there is plenty of oil in the tank. But I'm also premixing oil 50:1 to be safe.

With the engine running I disconnected the two blue wires coming from the oil tank, and the alarm was still sounding. When I disconnected the tan/blue wire from the temp sender, the alarm went off.

Does anyone have any suggestions from these symptoms as to what it could be?

From what I gather it could be:

-oil warning module
-overheat sensor
-themostat
-poppet
-buzzer in control box

I am considering at this point just replacing everything, but the warning module is like 100 bucks and I'd like to not buy that if I dont need to. I'm going island camping next weekend with the boat so I need to overnight some parts ASAP.

Thanks for all your help,

Marty

[marty53]

bump

[j_martin]

You found the problem. Replace the temp sensor.

They're cheep, (in construction) and fail in this way.

hope it helps
John

[marty53]

Resolution:

I replace the thermostat, temp sensor, poppet valve, all gaskets and fired the engine up on muffs and the warning horn came on immediately.

Disconnected the oil tank, then the temp sensor from the oil warning module and still heard the alarm.

Called the local merc dealer and sank $103 on a new oil warning module. Ugh. Problem solved. I guess the good news is I did a lot of maintenance. It looked like the thermostat housing had never been removed because there was still paint on the bolts.

Had the boat out on the lake for 4 days with no problems. This motor is bad (in a good way). It pushes my 16ft open bow Invader 160 40MPH.

Thanks for all your help! I saved hundreds over taking it in some place.

Marty