http://www.mercruiserparts.com/bulle...1999/EN_02.PDF
I know what they are and how they work, but why do some motors have them and some not? Same housing.

Thanks

Anyone has a motor that uses this housing but w/o the check balls?

Trying to determine under what circumstances they are not used.

closed cooling

Thanks.
Will I be able to run w/o the balls until I can get a set ordered? Standard cooling. I'm going to replace my 2 hose MPI housings for this unit this weekend to see if I can get my 50psi WP in check w/o going the relief valve setup. If it works as expect, I'll order the check valve assembly Mon.

cant answer that never tried to do her, I mean it, I mean run ..........,


hell you know what I mean, with out balls



Let me Know how YOU make out

The housing with "balls" is usually for an Alpha drive. They restrict water flow to the exhaust risers at idle. The water pump in the Alpha does not move enough water to cool everything at idle. Without the check balls too much water flows to the exahust causing the engine to overheat.
The Bravo pump moves far more water at idle than the Alpha. That's why the check balls aren't used in that application.

These balls on a spring allow water to bypass the t-stat when it's closed and go to the exhaust. When the t-stat opens the balls somewhat close and force more water through the motor. I would watch your engine temps if running without them.

May not be an issue.

You may want to check. I think the thermostat housing was redesigned with a more restictive opening to eliminate the checkballs. I think I remember seeing a TSB regarding this.
Gary

???

They came on my stock 2002 model 500 EFI's with Bravo XR drives.

Check this out:
http://www.marinemechanic.com/site/PAGE260.htm
http://www.marinemechanic.com/site/PAGE261.htm
Gary