Screech from the throttle box assembly

[Steve Foss]

Here's what my Dad just e-mailed me: Was just out in the boat. The gear box (shifting gears) started making this sound like a fire alarm going off....a screeching sound that kept on going....shut engine off, and when started it, sound returned....so shifted into gear and took it right into the dock, sound screeching all the way. didn't feel anything overheating, from my touch check-up....but don't dare take it out with the that sound....any ideas?

By gear box, he means the throttle/idle/choke/key assembly, not the shift mechanism on the motor itself. It's a late 70s deep V 16 Lund with a 35 Johnson and a console, not a tiller. We had the whole throttle control box and innards replaced a few years back, and it was functioning flawlessly a week ago.

This type of thing hasn't happened to me and I have no experience with it.

Thoughts?

[boatfixer]

Sounds like the overheat alarm Steve. I would want to verify the actual temp. Does it still go off after motor sat for awhile? If so it could be a faulty sensor.

[Steve Foss]

Well, I didn't even know that kind of setup that old would have an overheat alarm. I'll let Dad know about that possibility. Thanks!

[boatfixer]

Do you know the excact year Steve? It wasnt until about 81-82 that they were putting those in.

[Steve Foss]

It's a 78, but the throttle assembly was replaced a couple years ago with a much newer one, so that probably explains why there's an overheat alarm in it.

Dad tested things out today and ran the motor for quite awhile. Water pump/impeller was doing quite well, and there was no alarm, so probably a goofy sensor or perhaps there was some temporary impedance with the cooling water stream that allowed the motor to heat up and set off the alarm in the first place.

[boatfixer]

Steve I don't believe there is a sensor in the motor but could very well be an audible alarm in the control box that somehow went off

[Steve Foss]

Steve I don't believe there is a sensor in the motor but could very well be an audible alarm in the control box that somehow went off

If there's no temp sensor, what's the point of having an audible alarm in the control box?

[CAMAN]

I believe he is saying because its a '78 it doesn't have a sensor. The early '80's ones do though.

[Steve Foss]

OK, I see. There's an alarm in the control box but no sensor on the motor, so whatever noises the control box alarm makes don't really signify anything . . . except a very irritating screech.

Oh well, just one more boat repair project to put on my list.