2006 5.7L Mag Overheating

I've have another couple threads involving my work on swapping a Bravo 3 drive onto my Bravo 1 boat. All and all that's a big success. I figured I'd start another thread with this issue because I've determined its unrelated to the swap.

The problem I've having now is an overheating issue. There seems to be plenty of flow with the ear muffs, doesn't overheat until I get the boat on plane.

At first I thought it was my raw water pump. Changed that, same results. Checked the thermostat and that looked a little suspect so I changed that, same results. Even tried a 2nd raw water pump with the same results. I've taken most of the hoses off and backwashed the system and everything seems to flow well. The 3 things I'd imagine that are left to check is 1. Exhaust manifold and risers. 2. Circulating pump. 3. Raw water hose at rear of engine. (Plastic fitting or bravoitis?)

I'm hoping its not #3 because access behind my engine is horrible. I also would hate to throw more parts at the engine (manifolds and risers) just to find out that its the plastic fitting or bravoitis. I'm about ready to drop the boat off at a marina to get looked at because I've just spent too much time on this issue...which seems simple but is turning out to be a headache and too time consuming.

Is there anything else I'm missing here or is there a way to troubleshoot this better than I'm doing?

Check the hose from the bell housing to the transom plate, might be collapsing

I've had the drive off and the hose looked to be in good shape.

What is this in line on the intake side of the raw water pump? Is this a backflow preventer?

hose might be part of the quick-crack drain system

Bt Doctur said:

hose might be part of the quick-crack drain system

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I don't believe thats what it is. The red hose goes from the seawater pump to the transom. Maybe its a check valve? I dont see that part on any diagram.

Jesse Walter said:

I don't believe thats what it is. The red hose goes from the seawater pump to the transom. Maybe its a check valve? I dont see that part on any diagram.

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The black fitting on the red water hose is a quick disconnect coupler… it does need to be seated correctly as there is an O-ring in there and the pin needs to be holding it shut correctly which it looks like it may be… that mentioned the hose AD was mentioning is on the outside of the boat Portside next to the U joint Bellows. If that hose is twisted or aged out, etc., then you could be sucking air while up on plane.

I didn't see this info in your other thread . . .

Salt water or fresh water?

Raw water cooled? or Closed cooling?

Last time the manifolds and risers were inspected?

It might be fairly quick to take the water inlet fitting off the transom assembly for a 'bravoitis' check. (The inlet at the bell housing will look fine, while at the transom assembly it can be pinched).

tpenfield said:

I didn't see this info in your other thread . . .

Salt water or fresh water?

Raw water cooled? or Closed cooling?

Last time the manifolds and risers were inspected?

It might be fairly quick to take the water inlet fitting off the transom assembly for a 'bravoitis' check. (The inlet at the bell housing will look fine, while at the transom assembly it can be pinched).

Click to expand...

Brackish and some salt with raw water cooling.

I dont know when they were inspected. I bought the boat last year and went out 1 time last year. Didnt have any overheating problems then. Not that it matters on an older boat but it has only 240 hours and was serviced every year. It was kept high and dry at a marina since new.

Access behind the engine is almost non existent because of the design of the boat. (Stingray 250CR).