T-stat/ thermostat housing bypass
 

Guys i am in need of some serious help. Motor is going in now in a few days and i am stumped! It cant go in until i figure this out!! The original 350 mag mpi (2007 model) was in the boat and who ever had put an external oil cooler on the motor did an extremely terrible job re-routing the plumbing i have built a new motor for the boat and an redoing all of the plumbing and cleaning everything up and making it much more direct. I am ditching the factory mercruiser t stat housing in place of a hardin marine that has 2 -12an exits with a 3/8npt bypass hole. I am running all of the factory mercruiser accessory pulleys on front of motor with circulating + sea pump and factory serpentine belt system. I had forgotten that the exhaust needs to be cooled but the tstat will be closed and no water can escape. What should i do? Cross over system? If so i was hoping to find on like hardin has that has a place for the pulley on the crossover so i could run most of my original belt/pulleys. Or could i run without a tstat? We only run in 75-100degree weather. I need to do it right but quick. Any help and/or part numbers would be great!!! Water will be routed as follows. (Bravo 1) up through out drive to sea pump. From there to power steering cooler on bell housing. From there to oil cooler. From oil cooler the circulating pump. Through motor to tstat housing to exhaust. Then out the boat through a semi dry exhaust setup.

Also thermostat is a hardin brass hi flow 160*

The water through the bypass will cool the exhaust some until the thermostat opens.

In my case however, I found I had pretty high water pressure, so I ditched the thermostat and ran just a restrictor in it's place...

http://static.summitracing.com/globa...r-63440_ml.jpg


http://www.summitracing.com/parts/mo...F2waAj5F8P8HAQ

The problem in my case being to try and use the bypass by porting the thermostat and plug bypass hole or go crossover and redo all of my bekts to supply bypass hole with water?

Which restrictor did you use? The one with the closest opening to the thermostat?

Actually, yes... The red one..

I took the boat out New Year's day the water temp was in the 50's and the engine ran just over 100° water temp.
In the middle of summer with 80° water temps it runs about 150°

I DO run a thermostatically controlled oil cooler as well though...

What engine setup do you have? Im 434 sbc. Iron head and block. 10.3:1 compression on pump gas. And im in south carolina so summer water temp is decent. Im running aftermarket efi so i can adjust the temperature enrichment but want to make sure the rings get a good seal on cylinder wall

I had a roller cam, 9.5:1 compression, 427 in it...

Now I'm installing a Procharged 555 .. With the same cooling arrangement.

Im guessing running the 3/4 one (middle size) would put me right around the 160* mark where i want to be? The cooling system didnt end up hurting the motor did it? Also im running a 16" tube style 3" oil cooler from harden that is going to be plumbed pre entry to motor. Normally run around 3500-4k rom cruise

Assuming also you ran a sea pump picking up water from exterior and dumping through exhaust? Im using a b1 outdrive with xr upgrades