Cooling system bypass kit, Product No. - CSOT_01_61

[alcodiesel]

The A4 in my boat gas one of these installed. The description on MMI website leaves me not completely clear what it is for and what to do with the valve. Please educate me. The guy I bought the boat from is dead.

[Easy Rider]

Bill,

"Cooling system bypass kit"

If this is what you are referring to it's used to manually adjust the operating temperature of the A4. My moving the lever towards the closed position it will decrease the volume of cooling going towards the thermostat and increase the volume of cooling water to the block, thus lowering the temp. There are many opinions here whether or not the thermostat should be removed.

Chuck

[joe_db]

Cooling system bypass kit - late model - This valve is *backwards*. The less water goes through it, the COLDER the engine gets.
First thing is to determine the operating temperature of the engine. If the engine - assuming raw water cooling - stays at 140* degrees and below, no need to close it. If the engine gets hotter, you can adjust it down to 140. If the engine cannot be adequately cooled with the valve full closed, removing the thermostat is one option but may not fix it.

* salt and minerals precipitate out of the water above that temperature.

[JOHN COOKSON]

Open and close the valve a few times every once in a while. This will keep the valve from "freezing" or corroding in the position it is left in. It is a good idea to do this with the valves on the through hull fittings for the same reason.

Once water leaves the water pump on a RWC engine it can go through the engine and cool the the engine or go around the engine (ie the "bypass") and not cool it. The valve on the bypass balances the flow through and around the engine for optimal running temperature.

TRUE GRIT

[alcodiesel]

Thank you, guys. Correct me if I am wrong: Leave open for higher engine temp., close for cooler.
When fully warmed up, this season, it runs at 140 with the valve fully open, ergo, leave alone.

[JOHN COOKSON]

Thank you, guys. Correct me if I am wrong: Leave open for higher engine temp., close for cooler.
When fully warmed up, this season, it runs at 140 with the valve fully open, ergo, leave alone.

U R 100% correct in your understanding.

If U R so inclined and if the valve setting is in a mid position at cruise engine RPM you can help the engine warm up quicker by opening the valve up and allowing more water to temporally flow around the engine by way of the bypass. This will result in less water flowing through the engine for a quicker warm up. This is in effect a manual thermostat but with more positive control.

TRUE GRIT