Bravo 3 needed cooling

[Artemus6]

I have a 2006 DA 6.2mpi and bravo 3 drive. I'm wondering if the intake of water through drive is needed for cooling drive? Was thinking of making the intake through hull, then cutting section of hose out between transom and drive to let water flow freely through drive, and maybe installing a shower. Then plug hose inside boat of course. Problem is that I think hose is restricted through transom, causing high speed overheat. The hose housing through transom will be difficult to remove due to corrosion with bolts. Thanks. Will

 

[scoflaw]

That works fine, did it to mine and with the shower the drive stayed cooler

 

[Artemus6]

Was even thinking to use the existing seacock for the head discharge, since I dont use it the pump is bad. But not sure since it's just a big hole with no screen. Of course I would install a strainer inside before water going to the impeller. Will

 

[scoflaw]

Merc makes an upgraded transom hose that's mostly plastic to eliminate the Bravoitis. The 2 small bolts that hold the plastic gooseneck on shouldn't be a problem, the heads get a bit rusty but usually come right out.

 

[Artemus6]

The boat is in shop now getting new impeller pump, manifolds and risers. But I have to decide about the water hose intake through transom. The pic shows the bolts gone on water housing inside boat. It may be a whole days work to cut that off and do the outside work removing drive to install that new hose fix you mention. So it's either fix that or say forget it and do a through hull pickup myself. But I think that restriction caused the bad seals

in impeller pump. Overheated above 3800 rpm. Will

 

[scoflaw]

I think it would be less work to do the upgraded transom hose. Grind the heads off those 2 bolts pull the plastic gooseneck off and get some visegrips on those bolt shanks. Way less expensive too. you will need to find a molded 1 1/4" hose if you go the thru hull route.

 

[Artemus6]

Is that what size the hose is from transom to impeller 1 1/4? Its red and has a junction in the middle. And would I look for a strainer that size if I go through hull? Was also thinking a tee to draw water from drive and through hull. That way I can flush as normal. Will

 

[scoflaw]

Yup 1 1/4". It's hardwall and wire reinforced and doesn't like to bend much.

 

[Artemus6]

My mechanic thinks you should keep the water intake through outdrive for cooling. I wish I could get more opinions on this? I dont want to go through hull and have some damage happening to drive. Will

 

[scoflaw]

The drive will run cooler with the line cut like you described in post 1. Did it to my 2006 280 and the drive lube was noticeably cleaner after the same amount of hours.

 

[Henry Boyd]

We did our 280 exactly like your drawing. The tech who did the work contacted mercruiser who recommended keeping the water flow through the Bravo. The Merc people felt that a single drive on a large boat like the 280 would generate too much heat and limiting the water flow to pressure wouldn’t be enough.

 

[Artemus6]

After talking to my mechanic I'm thinking instead of making a new through hull seacock, I can use the one for the head pump out (I dont use it anyway because the pump is inop). Except it will need a scoop screen under the boat. Will

 

[ColoSR]

The thru hull works far better than the leg pickup to keep the engine cool.

I recently tied the drive Pickup back into the thru hull pickup to make it easier to get through the decontamination stations. So I can use both pickups or close the seacock and just use the leg. Mercury recommended that I use the thru hull + leg pickup and disconnect the flush connection.

The twin pickups is nice, won’t damage engine if I forget to open the seacock. Also, the muffs are easier to use than the fake a lake.

 

[Artemus6]

I guess all I need now is too figure out what size strainer and hoses, ball valves, reducers? To make all this happen using the existing discharge seacock for the through hull. Does anyone have pics of their mod? Will

 

[Henry Boyd]

The engine requires 1.25” plumbing. All fittings must be bronze, not brass. The tin in brass will leach out over time leaving a fragile porous shell that will simply crumble. Not a good feature for a through hull.

Hosing should be marine grade rubber with steel wire and exterior fabric reinforcement. It’s not very flexible so lay out your plan so it uses the most of straight runs. If you use the holding tank through hull ahead of the engine you may need to build a U type run using elbows to get hose into the water pump.

Likewise marine grade hose clamps should be used as well. Auto grade clamps are not all stainless and the non stainless parts can rust out and the clamps fail.