merc inline 6 165hp temperature problem ( ive changed the exhaust )

[stadium28]

Guys, i had a lot of rust with my old exhaust ( the original one ) and ive found this MOD EDIT as a replacement, but i have temperature issues... just on idle without runing it .
that exhaust has a thermostate at the back , the seller told me that i dont need to connect it ,, but im starting to thing that thermostat is blocking the water exit at the riser. could be?
see the pic ive attached , below.
Regards

Sebas

 

[stadium28]

Forget it , Ive just checked and the termostate si not present un the Exhaust.
With the original the cold water goes first yo the engine then to the Exhaust, with this alloy Exhaust it's diferentes, the water goes first yo the Exhaust, then engine, then back to Exhaust.
I'm gonna send the water first to the engine , then to the alloy Exhaust and i'll tell how was it.
Regards

 

[Scott06]

I think @achris is familiar with the water flow on this engine. I would have concern the copper tube is what constantly supplies water to the exhaust regardless of thermostat being open.
usually when thermostat gets removed something is FUBAR …

 

[Scott Danforth]

Have you started with the impeller?

 

[stadium28]

hi guys , thanks for your reply.

the water pump is new and checked , its ok
the impeller pump , its also checked and its ok

as this exhaust goes first the cold water inside , then goes to the engine and back to the exhaust , then to the river again...

ive noticed , that in the water from the exhaust came some " pressure " from the exhaust, thats normal ?

im attaching the original setup and at the right the new exhaust , to show the differences. In both setup the thermostat is not present .

in the next step file, its what im gonna do .. bypass the engine in the new exhaust, the output of the water at the engine plug into the in at the exhaust .

ill appreciate all of your recomendations, be aware tha im from Argentina and this replacement arent easy to find.

Regards
Sebas

 

[Scott Danforth]

hi guys , thanks for your reply.

the water pump is new and checked , its ok
the impeller pump , its also checked and its ok

by OK, what does that mean?

how quickly does the raw water supply hose from the transom shield fill a 5 gallon bucket with the motor running at 1000 RPM?

 

[achris]

This is a VERY old setup. Looking at your photos, you have gone from the later design exhaust manifold to a much earlier design (I have to ask, why the backward step?)
Here's the water flow diagram from the service manual...

 

[stadium28]

What ive done, was connecting the water intake first to the engine , then the to the exhaust manifold , as it cames on the mercruiser 165 original setup, but with the old aluminium manifold , and it works like a charm.