Where did my thermostats go!?

[mogfisher]

On my 89 150 blackmax I'm diagnosing a "no pee" scenario. Ordered the impeller kit and got new thermos. Went to put in the thermostats and the bottom part is gone. The part that sits in the housing is still there, but the whole spring assembly is missing. Should I pull the jackets and see if they are in there? Could they have fallen down and be blocking the passage? I cant imagine the gaskets are that much money but should I bother? All the hoses after the thermos are not blocked, so there must be a blockage inside somewhere or in the intake part of the lower unit. The PO said the impeller was good (just got this motor) but I'm replacing it anyway.

 

[clanton]

Re: Where did my thermostats go!?

I would install the waterpump, replace the water pressure valve diaphram, check the diaphram spring. Start and run engine with thermo stats housing off. Water should gush out of the housing. I would do this in water tank, not on muffs. Someone probley just removed the thermo stats guts. If you leave the stats out, you need a restrictor or the water flows too fast. www.screamandfly has information this engine , weeks of reading material. I think has 12 pounds water pressure, and tattle tale wil only flow strong after stats open. You have to check the pressure regulator.

 

[mogfisher]

Re: Where did my thermostats go!?

Water pressure valve diaphram. Where is that? Would I find it in that link? Is it the same as calling it a "poppet" valve? The parts guy didn't know how to find a "poppet" valve when I asked him. I definetly want to replace anything having to do with the cooling system. The boat has a factory installed water pressure guage and hopefully it works. Thanks for the quick response.

Adam

 

[clanton]

Re: Where did my thermostats go!?

poppet valve is correct name. Located starboard side, close to bottom of powerhead. Merc has online parts manuals, just need serial number of engine, photos and part numbers. Poppet valve may have updated spring.