Nordic,

I guess be careful what u ask for, because it looks like i have to add billet pullies now.lol but those engines look sweet.
please don't mind all the questions cause i'm sort of new to this. so if i plug the cir pump how would water get to the exhaust and would i still use a thermostat.

thanks

Yes, you still use a thermostat. The water exits the thermostat housing to the exhaust.
Once the link that SB is available you will see the flow diagram. These housings always bypass water to the exhaust even when using a thermo. When using a crossover setup and a thermostat you would need a bypass. Two completely different setups though.

Our setups above use a pretty high dollar recirculating pump (Meziere) but are no different in operation than the standard Merc stuff. The setups above with a 140* thermo come up to temp at 140* and never move regardless of how hard we run. 120* thermostats are available if you felt the need.

This is our water system of choice where we deal with large boating water temp swing (37*-80*)

Dave

SB,
that link is not working for me..
but u guys r saying is that i can plug the cir plug. and set the system up as if i had the bypass which i won't and everything will be ok..

I would take the circulating pump off and run a crossover !!!

Merc put a lot of engineering into those thermostat housings. Hold one in your hand and try to follow the passages .
This housing bypasses water to the exhaust regardless of the thermostat open/closed state. They also hold the thermostat above the temp senders and above the passage routing back to the circulation pump inlet. This creates a volume of water that is continuously circulated through the motor when the thermostat is closed. It will not allow cold water to enter this circulation path until the thermostat opens.

The small bypass hose traditionally connects below the thermostat on the intake and then to the negative pressure side of the circ pump. Because the Merc housing holds the thermostat above the passage to the 1.75” circulation pump inlet this bypass would just be redundant.

use the SS housing qaberdeen posted and should work fine .....

Ditto! That is the housing I am running on the red motor. Rock solid engine water temps reqardless of lake water temp. What more could you ask.

(not running a bypass hose by choice, my ciculation pump and intake are drilled for them in case these parts were headed for a car)

Well stated Rage!!
That's why Merc uses them up to their 800s. They have a ton more engineering money than us boys

Dave

Sorry about that - was down for maintenance but it is back up. My bad.

Here's the link again:
http://marineperformancetechtalk.com...sg5077#msg5077

Make sure you install the spacer, thermostat and internal gasket exactly like the diagram from Merc.
(you can find that on Mercruiserparts.com)
This is critical.