Mercruiser 5.7 Overheating

[AussieRon]

G'day folks, I have a 2001 Sea Ray 260 Sundancer with a Mercruiser 5.7 and Bravo 3 leg. The engine is over heating when on the plane at around 3000 rpm. At slow speeds at around 6 knots the temp gauge sits on 170 deg and seems ok. So I took the boat out of the water to antifoul it and get the Bravo 3 serviced. The Manifolds and Risers needed replacing so new ones were fitted. The mechanic also replaced the water pump impellor and said the thermostat looked ok. I took it for a test run today and the temp went up to 170 at 6 knots then on the plane at 3000 rpm the temp gauge started rising same as before so I dropped back to 6 knots before the overheat buzzer sounded. So talking to another mechanic he said it could be the Thermostat or a water restriction at the inner transom plate were the raw water comes in to cool the engine. Has anyone had issues with the inner Transom plate water inlet ? Mechanic said engine would need to be removed to fix.
Any other suggestions welcome.
Cheers
Ron.

 

[Craig]

Don't think the engine needs to come out. Not on my old Rinker 270 anyway. Drive needs to come off. about a $1200 repair as I recall.

 

[Espos4]

It’s not the easiest thing to access, and they aren’t the same boat, but on a 240 Sundeck, it can be done with the engine in place.

 

[Lazy Daze]

The bilge in your boat is a VERY friendly one. In fact, it's one of the easier ones to work on an engine in. Engine DEFINITELY does not have to come out. Most likely, your mechanic just isn't very familiar with this type of work or he would know right away. Suggestion... get the "block off" kit, then install a thru-hull pick-up with a strainer for the cooling water. It's a MUCH better, long-term solution.

Google "bravoitis" for more info about the blockage - lot's of info out there (and on this forum) about it.

FYI, your mechanic should also know that there are tests that can be done to check for the amount of water flow coming into the engine, without removing anything. And this should be done first.

 

[scooper321]

If the thermostat is a possibility, why wouldn’t you try that first? Has to be a lot easier (and less expensive) to swap that out than this water flow replacement. That would’ve been the FIRST thing I did, even before the manifold and riser replacements. Do the simple, most likely things first.

 

[AussieRon]

Thanks to you all so far for your information. I'm learning more about this issue that one mechanic called "Cats Arse" as the corrosion closes up the inlet. Also "Bravoitis" i'll google that as well. The Engine was overdue for Manifolds and Risers and a crack had appeared on one manifold leaking rusty water, to the outside luckily. (possibly 8 years old?) Water pump impellor was also due for replacement, (no vanes had broken off) so I hoped that this would have solved the overheating issue. Would removing the thermostat and test running engine be a valid test ? or would there not be enough "resistance" in the water flow ?

Also, another problem the boat has is the seal at the top of the outer transom plate is leaking water and there is corrosion around the steering arm and some side to side play in the leg. My mechanic is talking about removing the engine to replace the inner and outer transom plates to solve this issue and the Bravoitis, but this seems excessive to me (and expensive)
Suggestions welcome. Thanks in advance.
Ron.

 

[AussieRon]

If the thermostat is a possibility, why wouldn’t you try that first? Has to be a lot easier (and less expensive) to swap that out than this water flow replacement. That would’ve been the FIRST thing I did, even before the manifold and riser replacements. Do the simple, most likely things first.

Hi Scooper, I agree, however the manifolds and risers did need replacing (possibly 8 years old) and so did the impellor (3 years old) The Port manifold had a crack leaking water to the outside.

 

[AussieRon]

G'Day from Australia. Well it turns out that my overheating issue was Bravoitis. I took my Sea Ray to the biggest Mercuiser service centre in my area and they diagnosed and fixed the Bravoitis. They didn't have to remove the Engine but they did have to remove an exhaust elbow and power steering to gain better access to the water inlet fitting. All good now and no overheating on the plane. Thanks for your help and suggestions. I had never heard of Bravoitis before but I know all about it now.
Cheers
Ron.

 

[Lazy Daze]

Great - glad to hear it's back up and running properly!

 

[Happy Dayz]

good to hear fellow 260.. that is a very poor OEM design..

 

[AussieRon]

good to hear fellow 260.. that is a very poor OEM design..

My Mercruiser mechanic replaced the inlet hose with a new and improved version which prevents that problem from happening again. Agreed, the OEM original design is very poor, and to think that all Bravo stern drives will suffer from "Bravoitis" eventually !!

 

[Lazy Daze]

Time will tell if the "new" design will prove more reliable. It "seems" like it should, though.

Hands down, the best "fix"... add a thru-hull/seacock/strainer and pull the water from the bottom of the boat instead of through the drive.

"all Bravo stern drives will suffer from "Bravoitis" eventually !!"... just the ones used in salt water