Optimax Poppet Hose Removed and Plugged?

[Salty Dog]

I have a pair of 2001 150 Optis that someone removed the hose that goes from the poppet valve to the top of the block and plugged them off. Any idea what the reason is?

I had some cooling problems with the port motor and one of the things I did was replace the hose. Now it doesn't overheat anymore but at idle has 1.5 psi and the Smartcraft reads 170 and the analog reads 120 degrees. The starboard reads 3psi 105 on the Smartcraft and 110 on the analog.

If I plug the hose off on my port engine will I get better cooling at idle?

All cooling parts are new.

Ser # OT274141 and OT274461

Thanks

 

[Salty Dog]

Re: Optimax Poppet Hose Removed and Plugged?

She's running cool at high rpm but has low psi at idle. Should I remove the pressure relief hose and put the plugs back in?

I read on another forum to restrict the line down to 1/8". Anyone heard of this?

Thanks

 

[Texasmark]

Re: Optimax Poppet Hose Removed and Plugged?

In my engine of a lower hp, 3 cyl, the stat controls the temperature of the block up to 2500 rpm where the poppet is forced off it's seat by water pressure. This allows a much larger flow of water through the block for higher rpm operation and since a large volume is constantly running through the engine, on cold days, when the ambient water temp of the boating medium is low, the stat will remain shut after it opens....can't come up to temp. Besides, even if the ambient water temp is not cold, your stat probably opens at 143F like mine and my son's 150 v6 and even at the equator I don't know where you would get water that hot as a boating medium....maybe down stream of a power plant.

His engine had a stat at the top of each bank of cylinders and at the top, rear, center of the block, had the hose also (common to both banks) and the hose went down below the block to the poppet which dischaged in the "mid-section" and out. Seems Merc put that system together to improve high rpm cooling yet get the performance of the stat at low rpms. I don't think plugging it up is the right thing to do personally. Course if you boat in Alaska then you might get away with it.

My 2c,
Mark

 

[Salty Dog]

Re: Optimax Poppet Hose Removed and Plugged?

Thanks, I'm going to figure out a way to restrict it to 1/8"