200 hp yamaha overheating

[ROSSI]

G,day
I have a 200 hp Yamaha 2 stroke 1995 i just brought it
and she over heats when you get into it after only about
5-10 min i have removed the leg and there are no blockages
in the pick up
so far i have replaced
head gaskets (no blokages in heads or bores)
water pump impeller (no excessive wear on plates oring sealing)
thermostats (have run without them and still overheats)
flushed with a corrosion flush
we ran it without the cover at 4700 rpm for about 10 min and no trouble

she seems to go good with normal loads just when you get up it it overheats
any ideas and help would be great

[mike228]

overheating

have you tried replacing the poppet valve?

[ROSSI]

poppet valve

Im pretty new to outboards where is the poppet valve?
Dont mean to sound annoying or anything

[mike228]

poppet valve

not annoying at all! This is how you learn! The poppet valve is at the base of the block where the water goes in from the water pump to cool the head. At low RPM's it opens to keep water up in the water jackets to cool the engine-at high RPM's it closes because the force of the water pump keeps water circulating cooling the engine. They have a tendency to stick esp. on the SWS and OX 66's. I hope this isn't too confusing!
My 250 SWS II 76 degree overheats while i'm *****ing and at low RPM's. My mechanic suggests new water pump & poppet valve (also called high pressure grommet). Feel free to IM or email me if you have any questions.

[ROSSI]

thanks mate just to make sure im talking about the same thing
does it have a spring and a gromit its on the back of the motor
on the bottom just above the tell tale hose
if so i found that it was very tight in the gromit and would need
alot of pressure to open it im crossing my fingers

[mike228]

poppet

Hey! Sounds like we're talking about the same thing. The easiest thing to do is to just replace it but cleaning it and checking its elasticity will help. Let me know how it works out...I need to do the same thing!

[Tucker]

You should probably replace it. There is a new design that is dome shaped and should not stick in the grommet. They're pretty cheap from boats.net. Carefull replacing the grommet. The new one may tend to slip inside the water jacket (been there)

[ROSSI]

Thanks guys im trying to get one now will let you know when i get it in and
back on the water it would be nice if it was the problem im out of ideas if not

[ROSSI]

HEY GUYS,
Thanks for your help the problem is fixed so far I took her out last weekend
got it to 55mph and 5600rpm it was a bit choppy so wasnt able to hold it there too long but she didnt over heat or play up at all I ended up replacing every gasket on the motor including poppet valve and spring so cant really point to the problem but there was a little build up from its time in salt water nothing really heavy its all gone now and will never see the salt water as long as I own it

Thanks again