1996 Force 90hp overheat alarm

[sort]

I have a 96 Force 90hp that the overheat alarm went off this weekend on the lake. The motor hadn't run over 10 minutes when the alarm sounded...first time this had ever happened. We were going to do some trolling and hadn't even accelerated to quarter power since launching. I immediatlly shut her down and then tried a restart and it started right back up and no alarm...I checked the engine and it was not hot and water was coming out of the pee hole. Accelerated to full throttle and she ran smooth and to normal speed and rpm. Decided it was a fluke so went back to trolling station and 5 minutes later the alarm sounds again. Shut down and restart and no alarm but decided to take her out of the water and back home. Removed the lower unit and the impeller was perfect condition. Put back together and ran on earmuffs for 5 minutes at idle and water is coming out of the pee hole and the prop exhaust and no overheat alarm. Pulled the thermostat and it looked ok but would have replaced it if my dealer had been open and had part.<br /><br />Does anyone have any idea what could have caused the alarm?

 

[Trent]

Re: 1996 Force 90hp overheat alarm

Its time to check your overheat sensors. This is not the oil injected model..Right?

 

[DJ]

Re: 1996 Force 90hp overheat alarm

The Force wouldn't be oil injected. I'd replace the thermostat, it can't hurt.<br /><br />I also read on one of these posts that the Force engines had some plastic grommets in the exhaust system that would frequently melt and sometimes fall into one of the cooling passages.<br /><br />Perhaps some of the Force experts can expound on that idea.

 

[sort]

Re: 1996 Force 90hp overheat alarm

This is not an oil injected engine. The oil mix is probably a little rich if anything.<br />I sprayed water from a hose through the engine when I had the LU off and it came out of all orifices so I don't think it's a clogged passage.<br />I will replace the thermostat first as the new sensor unit is $36. <br /><br />BTW for all you Force fans...this engine shipped from the factory without a head gasket and actually ran for four years. I bought this boat/motor spring of 2001 and knew right away that something wasn't quite right with the way it started and idled. The dealer found the missing head gasket and Mercury agreed to pay all costs to repair but wouldn't claim fault. Boat has run great since and even holds low speed trolling for hours with no problem.

 

[trollhole]

Re: 1996 Force 90hp overheat alarm

I have the same year and model and same problem. I replace thermostat and it fixed the problem. Good luck. I also troll and have no adverse effect from doing so. Did it this past weekend for six hours straight. Have to decarb about four time a year though. Use 87octane with quicksilver oil.

 

[jrbpit1]

Re: 1996 Force 90hp overheat alarm

I had the same problem with a Chrysler 75HP motor. I replaced the impeller, & thermostat as well. It turned out that the head gasket was blown. I'd do a compression check to see if that is the problem. Also, after I replaced the head gasket on mine,the washers on the head bolts broke up on the bottom 3 bolts. This happened after 2 trips out on the river. This caused the the head to rattle loose and overheat again. I did torque the bolts to spec. Also, if the head gasket is the problem, get all new head bolts and get some heavy duty washers and get the head planed. A head gasket is about $35.00, machine work is about $40, and I think a new temp sensor is $35 or $40. And a torque wrench in inch pounds will be needed. Hope this helps.