Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: 1998 Merc 60 2 Stroke - overheat sensor questions

Posted by heimtun on 06/14/16 - 8:25 AM
#1

I'm having an alarm issue - i tested the the oil tank and sensor there is not the issue.

Before I go crazy on the overheat sensor I will be replacing the water pump (I have no idea of its age and don't see any record of it being rebuilt/replaced in the paperwork that came with the boat). I also plan to check the thermostat.

I'm leaning towards the sensor because the alarm is sounding during a driveway motor test with lots of water running through motor and steady stream coming out of the "pee" hole.

I will disconnect the sensor before I pull it out - for now, the connection seems to be sealed very well and don't want to break it until I retest motor with new water pump.

Question 1: Should I have an alarm on a driveway motor test? Does boat need to be in the water with the motor need to be submerged to silence the alarm?

Question 2: How the heck does one get the thing out? It appears to be behind a cover and I can't see how to get the cover off. OR is am I over thinking this and one just needs to remove the hex bolt over the wire?

Question 3: Testing senor... How? Sourcing sensor at a reasonable cost.

TIA

Wayne

Posted by fitz73222 on 06/14/16 - 10:50 AM
#2

Your engine can have a bad thermostat and pee water like a 6 year old. The water discharge for the "pee" indicator is before the thermostat in the water flow path. Does the alarm sound after the engine has been running for several minutes or right away? Does it only alarm on the flush or also does it in the water? Your engine has a 110 degree thermostat in it. If you have a laser temp probe you can shoot the laser at the thermostat housing and see what it is reading, then progressively go around the block and probe all the areas and look for any hot spots. Do these checks and then we can talk about next steps.

Posted by heimtun on 06/14/16 - 11:26 AM
#3

Thanks for reply.

Have not had boat on water, so for now just on flush. It alarms with key on and does not stop - so doughtful engine is even warm. I do have a laser temp sensor - but like I said - engine is not even warm.

Wayne

Posted by fitz73222 on 06/14/16 - 12:15 PM
#4

Disconnect the cylinder head temp sensor wire where it connects to the harness. The connection will be under a black plastic tubing maybe 4-5" from the sensor in the head. Make sure the harness side of the connection does not touch ground. Turn the key on. If the alarm sounds, the warning module is defective, If the alarm does not sound its probably the sensor.

Posted by heimtun on 06/27/16 - 6:19 AM
#5

It turned out not to be heat sensor but the oil sensor. I've started another thread on that.
http://www.whalercentral.com/forum/vi...d_id=22797