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2005 5.7 Mercruiser Horizon MPI sn OW061013

S

Stelios

Member
2005 5.7 Mercruiser Horizon MPI sn OW061013

This is closed cooling ( heat exchanger) (dry joint?)
This winter I had the yard replace the raw water intake hose
I replaced the elbow gasket
Quicksilver OEM MerCruiser 4.3/5.0/5.7/6.2 Dry Joint Closed Exhaust Elbow Gasket

27-864549A02

First ride this season after 5 mins I had overheat and guardian mode - 185 deg F so I shut her down

1. I believe I installed the correct gasket properly. If I didnt, could that cause an overheat?
2. Could the yard have screwed up something on the hose taht coudl cause an over heat?

Thanks
 
Based on your serial number, This link (for this web site) shows the gasket for (CLOSED COOLING).


It is the same part number you posted.

If the engine did not have an over heat issue before the "yard" changed the hose then I would have the "Yard" Find out why its over heating now.

Your question is to vague for an answer.

No real history of what or why the hose or the manifold gaskets were changed.......etc.

Is there any antifreeze in the system?
When was the impeller replaced last?
What troubleshooting have you done if any?
Thermostat?
Is this an Alpha drive or a Bravo drive?
 
Hose was original and showing cracking - dry rot - routine maintenance \. Small sign of leak at exhaust elbow gasket ( not manifold gasket) also routine change

Antifreeze - yes

Impeller - not sure will check

Bravo 3

Thermo - not checked yet

There is enough info to answer the questions:
If the gasket was installed wrong ( I dont think it was) could that cause over heat?

Could the hose installed wrong ( air leak or something) cause overheat?
 
Ok. See Bravo uses a engine driven pump/impeller vs Alpha which uses an outdrive (internal) impeller.

Very important info!!!!!!!!!

1. Closed cooling, if gasket at elbow/manifold was installed wrong or wrong gasket, Antifreeze may/could escape and leak either into boat or out exhaust.

2. Considering engine driven pump impeller was replaced, I would start there.

Confirm hose routing, Incoming water hose to in of pump housing.

You can remove out hose from pump housing and using hose/muffs at drive start engine and see if water is being pumped out.

Only other thing that comes to mind is, how is impeller keyed to shaft? If it required a pin/key maybe its missing or fell out when new impeller was installed?
 
One thing that is not clear is where the raw water is coming from?
Is it being sucked in thru the drive or does your boat have a thru hull fitting?

Bravos (I, II, III) have a flaw in the pass thru and they use a pinch design to hold the incoming water hose in place vs a thru transom fitting for both sides to connect to, Because of this the area around the pinch fitting as it is aluminum begins to corrode and as it does it swells and causes the pass thru area to shrink and it compresses the hose/pinch section and severely reduces water flow. This could be an issue or a contributing issue.

Here is a link showing the design of the transom plate and the water hose connections. Item 15 and 16 are the incoming water hose and pinch fitting on the outdrive side (If the raw water is being sucked thru the drive). Item 20 shows the engine side hose fitting and yours should be similar as they use a few different styles.


This link is the bell housing and it shows where the hose (item 15 and 16 above) and where it connects to bell housing. See item 4. This is another "pinch" fitting for the end of the shaped hose.



You have your work cut out for you to track down the overheat problem.

An answer to one of your questions, If air is being sucked into incoming water stream it WILL cause overheating. the air displaces the water and thus lack of water flow to properly cool antifreeze and/or lack of water flow to cool elbows and exhaust as the elbows have raw water flowing thru them at all times to keep exhaust gasses cool so rubber exhaust boots dont melt.
 
Last edited:
On dry joint elbows, the gasket is clearly stamped "THIS SIDE UP".... If installed upside down condensation that occurs on engine start up drips onto the valves of the middle two cylinders causing them to rust. If installed correctly, condensation is trapped in the joint gasket and is boiled off harmlessly as the engine heats up. Merc calls that gasket a "turbulator"... Won't cause your problem, however should you ever open that joint verify correct gasket installation.
 
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