General Question

[D_J_Winn]

When I drain my raw water sea pump/hoses, and install a new thermostat approx. how long after start up will it take my 1997 MerCruiser Bravo III 5.7 LX to get water exiting from my thru-hulls?

Also when I start my engine should I get water exiting my thru-hulls continuously, right a way, or do I need to wait till the engine hits a certain temp to allow thermostat to opens? (same engine) Thanks

 

[TilliamWe]

Re: General Question

Water should ALWAYS be exiting the exhaust.

 

[SuperNova]

Re: General Question

On initial start-up, it can take a few minutes for the water to show at the exhaust point, depending on what all has to fill.

 

[Fun Times]

Re: General Question

I would say to fill the engine block up and to have water coming out of the exhaust it sould be right around 45 seconds as an avarage at 1300 rpms that you should be reving the engine up to after start up per your manual.

 

[TilliamWe]

Re: General Question

On initial start-up, it can take a few minutes for the water to show at the exhaust point, depending on what all has to fill.

Nope, wrong.

On his engine, the only thing that has to fill is the exhaust manifolds. Well, on everyone's motors that's all that has to fill. Mercruiser exhaust systems expell water all the time, regardless of engine temp. If you actually look at the hose routing, you will see that the hoses to the bottom of the exhaust manifolds are not dependent on the thermostat opening. Gosh, if they were, the exhaust shutters would never survive, they'd burn up every time. And they don't.

Maybe a couple seconds for the water to come out the exhaust, but not more than 10, or you've got an issue.

 

[TilliamWe]

Re: General Question

I would say to fill the engine block up and to have water coming out of the exhaust it sould be right around 45 seconds as an avarage at 1300 rpms that you should be reving the engine up to after start up per your manual.

Not how it works at all. Block could be empty and water would still come out of the exhaust. Look at the thermostat housing closely someday and you'll understand. Water goes to the exhaust manifolds (and risers) all the time.

 

[JimKaz]

Re: General Question

Sounds like you clog somewhere. Flow diagram is in the manual. Start going hose by hose until you find it. Looks like you now know what helped burn up that rough water pump......

 

[SuperNova]

Re: General Question

I know for a fact that sometimes it takes long enough for me to start worrying about whether I have the hose turned on enough or not. Maybe it just seems like a few minutes and it actually is only 20 seconds or so, I never timed it to be exactly sure, but I do know sometimes it can take some time.