Cooling orifice tube

finaticmw

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Jun 18, 2012
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41
Good morning. I recently had my 2009 Bayliner 245SB, powered with a Mercruiser 5.0 MPI and Bravo 3 out drive, in the shop with overheating issues. They found impeller fins in the orifice tube. Since the repair the boat ran fine without going into high alarm. The gauge shows more heat than I like but I was told the actual temp is 7-8 degrees lower per the onboard computer. I plan to add a secondary digital temp gauge so I know whats going on. I've tried but can not locate info on where this orifice tube is located. Can anyone shed some light on this for me?
 

tpenfield

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Jul 18, 2011
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What's a cooling orifice tube?

Typically the temperature is taken at the thermostat housing. You may want to get the cooling flow diagram for your engine. You can also use an IR thermometer to sample the temperature at different areas of the cooling system and compare it to the gauge.

In my previous boat, the gauge read about 5-8 degrees higher than the computer sensor on the engine.
 

finaticmw

Seaman Apprentice
Joined
Jun 18, 2012
Messages
41
What's a cooling orifice tube?

Typically the temperature is taken at the thermostat housing. You may want to get the cooling flow diagram for your engine. You can also use an IR thermometer to sample the temperature at different areas of the cooling system and compare it to the gauge.

In my previous boat, the gauge read about 5-8 degrees higher than the computer sensor on the engine.
Thanks.. I have a temp gun. I have confirmed the temp difference from the thermostat housing to the gauge but it's not an easy task on this boat. The temp gauge face leaves at lot to the imagination. "By the gauge" I feel like my temp on the first run was around 200 at running speed. The pictures shows idling temp. At speed it is on the first hash mark past this. I feel that if I install a secondary, digital temp gauge I could better monitor real time running temp.

Sorry unable to upload pictures for some reason. It would have shown the needle slightly past the 175 hash mark at low speeds. It seems each additional hash mark is about 25 degrees which is why I suspect near 200 degrees "by the gauge".
 

tpenfield

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200 (ish) seems a bit high. Should be more in the 160-180 range. The senders and gauges are not all that accurate, so do verify with the IR thermometer
 

kenny nunez

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Jun 20, 2017
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Any boat with a Bravo that is getting old needs the water pickup plumed through the bottom with sea valve and connected with a “Y” fitting connecting the drive incoming water to the bottom incoming water .
If you go on the Donzi site you will get the idea how much this a problem solver.
 

finaticmw

Seaman Apprentice
Joined
Jun 18, 2012
Messages
41
Any boat with a Bravo that is getting old needs the water pickup plumed through the bottom with sea valve and connected with a “Y” fitting connecting the drive incoming water to the bottom incoming water .
If you go on the Donzi site you will get the idea how much this a problem solver.
Thanks I'll check that out too
 

cyclops222

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Mar 21, 2024
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1,294
E P A garbage wants HOTTER engines to lower emissions. Catalytic Converter engines are very much hotter. Agree with check the thermostat number on it.
 

finaticmw

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Joined
Jun 18, 2012
Messages
41
Have you checked the thermostat? Did the shop install the proper one?
The thermostat was the first item to be replaced. It was done by a mobile mechanic and I have no idea what thermostat he put in it. Since the initial problem it has a new thermostat, new manifolds risers and elbows, a new raw water pump ( mine broke the shaft) AND THEN it went to the dealer where they found the rubber pieces from old water pump failures.
 
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