what temperature sets off the alarm horn?

1995 johnson 115 ocean runner...

have been dealing with seemingly weird issues with temps since i got the motor. Have made several posts about it..

installed temp sender, and had them wired through a selectable switch.

was getting weird temp guage activity.

finally pulled the switch and installed a second temp guage..now got a sender and gauge for each head.

installed a new water pump( only because i ruined the prop shaft and repalced the LU)
water pressure is good 25 lbs at 3000 rpms

ran the boat yesterday the guages start at 120...both barely seemed to move from the 120 mark for an hour or so...i was putzing around , never more than 3000 rpms.. < i thought , dammm guages dont work now..i did something wrong on the wiring..

eventually on the way back i took the motor up to WOT..it was only 5000 rpms( because my good prop was ruined when i damaged the last LU and i was running too much pitch on the current prop)

but the one head's gauge ran up to 185 degrees!!!, the other guage barely seemed to move.. making me think it might have issues..

the one that went to 185 was the new install.. the other was the one that now makes me think it is defective.

anyway as for the 185, when does the alarm for over heat normally come on???

and what is going on when the temps wont go above 125 for and hour and a half of cruising and stopping and starting...and runiing up to 3000 rpms.

but once it goes to 5000 the temps rises..and water pressure was close to 30 PSI!!!

thanks

bob

Re: what temperature sets off the alarm horn?

Put the temp switches in a pot of boiling water, see what the guages show.!

If one is off, swap them around, try new section of test wire, could just be a ground or poor connection.

Re: what temperature sets off the alarm horn?

jonesg said:

Put the temp switches in a pot of boiling water, see what the guages show.!

If one is off, swap them around, try new section of test wire, could just be a ground or poor connection.

Click to expand...

well the ground in the system has to come through the motor block( via threads) and the ground connection from the guage to the battery negative side..

if I was going to boil some water close by the back of the motor , so the wires from the gauge will reach the pot of water, Ill have to fashion some form of ground from the body of the temp sender!!!

other wise, id have to pull the temp guage from the dash and rewire in the kitchen with a 12 v battery..

my company has a infared thermometer, I can borrow tomorrow....I think ill try that first.

but i also am wondering about the system check horn....if the guage is reading right , shouldnt it have gone of at 185 degrees????

bob