I'm trying to understand the purpose of those check-balls on the thermostat "T" fitting. Is it just to help the engine warm up faster until the thermostat opens?
My starboard exhaust always runs way to hot no matter how much I mess with those stupid check-balls even after the thermostat opens. It will work for a while but then goes back to uneven water flow after a couple of weeks. Seems like a piss-poor design.
If I remove them both banks run nice and cool but I've read that this will cause problems.
You may want to contact Mercruiser help and ask them this one. I used to see those check balls in the 80’s but then they went away, didn’t know they were using them again. My 1997 5.7 doesn’t have them nor did my 1993 4.3.
Even without them it’s common for one side of the exhaust to run hotter than the other but within 20*.
When I say "too hot", I mean WAY too hot. (I should buck-up for a thermo-gun) It seems to have something to do with insufficient water supplied by the outdrive once the thermostat opens but other posts say that alpha 1 gen 2 outdrives (like mine) have better water flow volume and it's not as big of an issue, if any. Apparently Bravo outdrives have much better water supply because they're designed for use with bigger V8s, but I don't want to risk overheat issues just to test that theory. It could put a downer on my whole days outing. Thanks for your comments. Cheers!
Yes a IR temp sensor is a great investment. I prefer actual temperatures to do diagnostic work. The Bravo drives incorporate an inboard belt driven raw water pump that has a much bigger impeller with more vanes as well.
Thanks Mike, I might actually install a belt driven inboard pump and loose the impeller in the outdrive and the silly check-balls. Way better cooling and easier to diagnose and service.
Thanks Mike, I might actually install a belt driven inboard pump and loose the impeller in the outdrive and the silly check-balls. Way better cooling and easier to diagnose and service.
You will need to leaving the impeller in the drive to help cool the upper gears of the drive but cut the hose going between the bellhousing and transom plate plus an internal blockoff plate. The inboard pump will use a thru hull to pickup the raw water. I guess you could use the drive water pickup and just delete the impeller as this will still allow for cooling of the upper gears. The drawback of this way is the transom hose is smaller than what a thru hull hose would be but that’s what you have been living with.
2005 Mercruiser 4.3L V6 thermostat check-balls
Linear Mode
