[DukesFin]

1990 Yamaha 150 ETXD

I (SOMETIMES) get an overheat alarm when trolling. This only happens sometimes. I shut the motor down and sometimes I can fire it right back up and the alarm is gone, other times, I have to let it sit for 15-30 minutes and let it cool off before the alarm stops.

Where do I begin?

The first time this happened (about a month ago), I immediately replaced the thermostats because they were cheap and had no idea when the last time the PO did it. I thought this solved the problem, but it's come back up again...

Again, this is at low speed/trolling/idle only. On plane, I never get the alarm. Also, the water pump is new!

Thanks in advance for the help in troubleshooting!

[svilla]

There is also a low speed valve in the cooling system too. I have a 1997 150 2 stroke and it was very easy to get to mine. Any how mine had lots of old salt build up and did not close correctly. So I just removed the cup, spring, and plastic poppet, and cleaned all the parts real good and also the mounting surface for the poppet and that did the trick.

http://www.boats.net/parts/search/Ya...ASE/parts.html

you are looking at parts 49 - 53 all you need to do is remove and clean these parts, replace any that are bad.

[DukesFin]

I thought it would be either the PRV (what you mention) or the temp senders.

I might go ahead and replace all of it since I have NO idea when the last time it was cleaned/done!

Thx

[svilla]

Yeah it only took me like 15 min to remove, clean, and replace mine. Lets us know how it turns out.