Outdrive cause overheat engine/Bravoitis = thruhull bypass?

[incorrigible]

I’m buying a 2012 Formula 290 BR w 377 Mag, Bravo Three and engines are overheating under heavy load/80% rpm. one worse than the other.
It has closed loop cooling and all raw water components (pump, elbow,riser,manifold, exchanger) have been replaced however we are still overheating on max rpm runs. Merc tech says the only remaining issue could be a case of “Bravoitis”. Hose in the outdrive that picks up the raw water is internally clogged or corroded. Tech says a simple solution is to just pull raw water from two new thruhulls and ignore the outdrives. Sort of makes sense. What about the fact that the outdrives aren’t getting water pulled through to cool the gearcases? Is this when one of those Halo Showers comes in? I’ve read that Formula puts these halo showers on their B3’s as standard equipment? I’m not near the boat to verify.

Any my help or suggestions are appreciated. Thank you.

 

[AllDodge]

Merc tech says the only remaining issue could be a case of “Bravoitis”

I think you need another Tech. He has replaced all kinds of things and doesn't know why its over heating, and is guessing its Bravoits because that's the only thing left. To find out if its Bravoits, all it takes is remove the hose fitting at the transom (inside) and look

If it is Bravoits, which I'm suspect due to this is a 2012 model, it just takes the new design Bravo tube which the 2012 should already have I'm guessing.

What about the fact that the outdrives aren’t getting water pulled through to cool the gearcases? Is this when one of those Halo Showers comes in? I’ve read that Formula puts these halo showers on their B3’s as standard equipment?

The water going thru the drive would continue it would just exit spraying inside the transom assembly. The Simrek drive shower is installed on the Formula B3's and are need on the B3 because they generate so much heat

If your sure they are overheating (have used a IR temp gun on thermostat housing) then remove the hose coming from the pump and place a piece of clear hose in it. Run it and see if there are any bubbles

What is you engine serial number?

 

[incorrigible]

Thank you for response!
port 1A647815
stbd 1A647817

 

[AllDodge]

Took me a while to find and color in the raw water side. As with all motors, the only way they over heat is to not have enough water going thru the heat exchanger (HE). The thing can heat up by the engine circulating pump not moving coolant, or the raw water not passing thru them enough. I have not been able to determine what the item the arrow is pointing to.

The angled tubes (venturi) cause a sucktion so they should cause water to flow in correct direction.

Has the temp been measured with a IR gun to verify gauges?

 

[AllDodge]

Also when the manifolds were replaced were the correct gaskets used?
What are the port and starboard equivalency ratios (scanner needed to do this)?
Is the guy who looked at it a Master Tech (should have a plaque on the wall with a date)?

 

[409]

What is your water pressure? Guessing you have Vesselview. I just installed raw water pick ups and strainers on my 08 34PC-496 Bravo3. Its a great investment even if it’s not the current problem. Bravo 3 through transom is only 3/4” going into a 1.25” hoses. Not a great design. I had “slipper” shell growing in my outdrive (salt water). Went up Connecticut River last year. Shells died in fresh water and were sucked into the raw water hoses. 2 shorthauls in Chester, CT. Mercruiser makes a block off kit and I have factory drive showers.

 

[SabrToothSqrl]

Also when the manifolds were replaced were the correct gaskets used?
What are the port and starboard equivalency ratios (scanner needed to do this)?
Is the guy who looked at it a Master Tech (should have a plaque on the wall with a date)?

For my understanding, can you define 'correct' gaskets? I've seen 2 with Merc for the manifolds to the elbows. Ones which are 'wide open' and ones with small 'holes'. I would think that bigger holes = more water = more cooling = better... but I didn't design it...

thanks!

 

[AllDodge]

You have closed cooling so you would use 27-8M2004414 which do not have holes in them. I did speak to quick about the correct gaskets though, if you used the ones with holes, then your antifreeze goes out with the exhaust

https://www.ebay.com/p/Mercury-Merc...7-8m2004606-Gasket/547406521?iid=302730380437

 

[gixr04]

+1 on thru hulls. I did this after 2 yrs of whining about overheating.. tadah! No more problems. As added piece of mind I removed heat exchangers and barnacle busted couple hrs ea. I measured pick hose from drive... 5/8”..... REALLY?? What genius came up w idea of tiny hose trying to feed 1 1/4? Higher rpm resulted in pump cavitation..