2000 150hp 2 stroke overheat

[Rayder36]

This my first post on the Forum.. Have been reading a lot of Threads.. This forum is a Great tool.............

Here is my problem...
My 2000 150hp TXRY 2 stroke goes into visual alarm [have no audible]and shunt of rpm when I get into the plus 4000 rpm's. Have replaced the Impeller, tested the stats. They open at 130-135. Tested each cylinder during overheat alarm and they read around 140 temp. when tested with infared heat gun. Inspected all the spark plugs looking for a cylinder issue, none found. It runs normal at all speed ranges.Today I cleaned out the poppet valve. Test ran it in the Calusahachee with the same overheat results!!!

The engine history is: It is stored out of the water since birth. Flushed by me every time it is back on the lift. Sure could use some advice.......

Thanks

Rayder36

[99yam40]

Pull and test the temp switches/sensors to see what temp they change states closing and opening.
If they funtion properly ( withing the specs)then you probably have some blockage causeing hot spots at the switches/ sensors area in the head/block

[Rayder36]

99Yam40

Ok that will be my next step.. I need to get a Service Manual. Any good direction here? I see them from $28.00 to $95.00 on line.

Many Thanks Rayder 36

[99yam40]

You can do a online search for marine manuals and find all sorts of places to get them. even this web site Yamaha Outboard parts sells some.

I have read where some have used this down loadable site and said it was ok, but I have not used it myself. Yamaha Service Repair Manuals, Download Service Repair Manual Instantly only $9.99

[Tucker]

I'd get the Yamaha hard copy. Yea, it's about $100 delivered but it'll pay for itself in no time. While the manual is very good and shows you how things go together; it does little to help diagnose problems. There are some smart cookies here that will give you "the rest of the story". You might want to print out some posts and put them in the appropriate place in the book.

With the loving care your giving that motor it's hard to believe you got a blockage but is sure sounds like it. Not sure if you need to pull those sensors, you've confirmed overheating with your heat gun. Rodbolt should be able to chim in with what temp those sensors close. Unless someone chimes in with the cure, I would get some Salt-Away, pull the stats out, and flush the motor in a tub. Pulling the heads to clean is a last resort, but that's me talking. Where you at Rodbolt?

[99yam40]

140 is not overheated.
The over heat alarm switch on my c40 closes around 200 and the engine warm switch closes around 120.

Pull and test to make sure they are doing their thing at the correct temps

[rodbolt17]

any visual on that engine should trigger the audible except a low remote tank alarm
have you tested the audible alarm system?