2001 Optimax

[jigger]

I have a 2001 Optimax 150 hp. Yesterday was my maiden voyage for the season. The engine fired off on the second turn. I checked the tell tail and there was a nice stream coming out. I watched the temp rise and hold at 140 degrees before I cast off. I made it to the mouth of the marina and pushed the throttle forward to power up. The throttle cable locked in place as the Guard Alarm kicked in not allowing the engine to go above 1000 rpm's like it is suppose to do. I looked at the temp. reading and it was showing 185 degrees. I turned around and head for a dock. When I got there the reading was down to 165 and dropping. I shut down the engine in hopes of finding something wrapped around the intake and there was nothing. I restarted the engine and release the throttle I brought the rpms to 1200 and watched the temp. It started to raise again. It got to 195 degrees and suddenly to dropped down again to 142. Then it went back up. I put my hand in the tell tail water and it was cool to the touch. Because the temp kept going up and down I pulled the boat. I replaced the water pump and thermos and popit valve in the winter of 2007. So this is the second year on them. Could this be a bad thermostat or a bad temp sensor. Any ideas would be apprecated.

[Eggsuckindog]

The stats are certainly the easiest to check, does sound kinda goofy, may be just let it run some. Sounds like something is closing and opening which is what the stats do.

[jigger]

I pull the thermostats and put them in a pot of boiling water. Both of them would open but not completely. After changeing them and running on the muffs for a while. I was getting a water temp of 180 constant. I put the boat in and on the troll of 4 kts. the temp stayed at 172. But running on plane the temp would stay down around 145.

[Cuzwecud]

probly would not hurt to change out popit valve, the part is not expensive, as I've been told they could cause heating problems if not functiong properly. Have you had the new thermostats installed sound like you have if they are 140F.

[Eggsuckindog]

I think thats right where is supposed to be - it goes down after the popit valve opens at about 2500 RPM

[jigger]

Yes I have chaned the thermostats. I planning on changing the popit this weekend just to be on the safe side.

[knotreel]

definately sounds like the poppet. Usually you can just clean it up and it will be good. Get a few gaskets. You will need to pull the lower cowls, it is on the star side.

[Cuzwecud]

Try this or check temp sensors.

Water Pressure Check

Water pressure may be checked by one of three methods;

• Use a Digital Diagnostic Terminal (DDT) [91-823686A2]

• On engines equipped with Omega gauges, water pressure is an available readout.

• On engines not equipped with Omega gauges, a water pressure line is provided that

exits at the front of the lower cowl. A dash style gauge may be connected to this line

to register water pressure.

WARNING

Shut off engine and refer to troubleshooting chart if water pressure is not within

specification. DO NOT exceed 3000 RPM in neutral.

Idle 1.0 – 3.0 PSI

(6.8 – 20.5 kPa)

Poppet Valve Opening 4 – 9 PSI

(27.4 – 61.6 kPa)

W.O.T. 12.0 PSI (82.1 kPa)

Minimum

Cooling Water Strainer

The cooling water strainer filters cooling water flowing to the port fuel rail and air compressor.

1. Remove bottom cowl. Disconnect water hose from the strainer plug.

2. Remove and clean strainer.

3. Apply Loctite Pipe Sealant w/Teflon (92-88504) to strainer threads and reinstall strainer.

Reconnect water hose and secure with sta-strap.

a

57543

a - Water Strainer