Inboard raw water not pumping out of back overheating

May 17, 2004
5,694
Beneteau Oceanis 37 Havre de Grace
I'd definitely open the end cap on the heat exchanger and check for blockages there. That's a good place for broken impeller blades and seaweed to get stuck. Also check the impeller itself as others have suggested. Universal mixing elbows don't seem to have the same problems with blockages as the Yanmar design but it might still be worth checking if everything else checks out.
 
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Jun 16, 2018
13
Cal Pearson 29 San diego
UPDATE: removed heat exchanger and definetly needs so tlc. Gonna let it soak in some barnacle buster for a day to clean it out.
If it is not the heat exchanger is it possible my thermostat is closed? Would that prevent the water from circulating out? Is this my thermostat?
Checked mixing elbow and water isn't reaching it and has black burnt stuff inside but definitely not clogged
 

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May 17, 2004
5,694
Beneteau Oceanis 37 Havre de Grace
If it is not the heat exchanger is it possible my thermostat is closed? Would that prevent the water from circulating out? Is this my thermostat?
I've heard of some engines blocking the whole reason water circuit with the thermostat, but on most engines (and our old Universal) raw water still flows regardless of thermostat state. Can you try running the output of the raw water pump straight into a bucket to see if it's pumping, then work your way down the circuit from there?
 
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May 17, 2004
5,694
Beneteau Oceanis 37 Havre de Grace
Yah I did that. Is that the housing for the thermostat?
Yes, that looks like the area, but if you follow the raw water circuit it probably doesn't go near there, so it's probably not related to lack of water in the exhaust. The raw water will go from thru hull to pump then heat exchanger then mixing elbow. The thermostat only affects the routing of the fresh water.
 
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May 17, 2004
5,694
Beneteau Oceanis 37 Havre de Grace
There is no fresh water coolant system
There's a heat exchanger so there must be a fresh water system. The heat exchanger basically does what a radiator does for a car - cools the fresh water. A car radiator uses air for cooling; the boat engine uses raw water through the heat exchanger. The thing you're pointing to in post 14 that says Universal is the coolant resevoir. Open the radiator cap on it (when the engine is cool) and there should be antifreeze / fresh water mix.
 
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jviss

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Feb 5, 2004
7,089
Tartan 3800 20 Westport, MA
If it is not the heat exchanger is it possible my thermostat is closed? Would that prevent the water from circulating out? Is this my thermostat?
No.
As @davidsailor26 indicated, you have a coolant circuit and a raw water circuit. The heat exchanger is where the raw water cools your engine, by cooling the coolant that circulates through your engine. They are separate.
 
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Jul 23, 2009
916
Beneteau 31 Oceanis Grand Lake, Oklahoma
Looks like a fresh water cooling system to me.

You will need to address both sides of the system, coolant and raw water.

The heat exchanger didn't look that bad to me.
 
Jun 16, 2018
13
Cal Pearson 29 San diego
Ok you guys are right. After I finish up I ad 2.2 quartz of coolant. Is there a process for that or is it that simple? Heat exchanger had all holes completely filled with build up so once that comes out of the barnacle buster in a few hours I'll reinstall it.
Just pulled out my thermostat could this prevent raw water from pumping out? How do I diagnose the thermostat?
 

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May 17, 2004
5,694
Beneteau Oceanis 37 Havre de Grace
Just pulled out my thermostat could this prevent raw water from pumping out? How do I diagnose the thermostat?
Water should pump out regardless of thermostat state. It will only affect routing of the fresh water. If you want to test it anyway you can put it in a pot of water. The thermostat should open when the water gets up to its set point (maybe 160ish).
 
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Jun 16, 2018
13
Cal Pearson 29 San diego
Did the boiling test on thermostat and its in working order. Just finished putting heat exchanger back in started up the motor and saw a leak on the side so it needs a new gasket to prevent the leaking. No water was coming out yah. Tightened the leak and it is a small trickle but then I look over board AND WATER!!!!!! pouring out of the exhaust and it was glorious!!!!! Thank you everyone for the great advise!!! First engine maintenance and learned so much!!!!
 
Jun 19, 2004
365
Island Packet IP 32 99 Forked River, NJ
I know this is different from your exhaust elbow, but this is what we found when we disassembled our cast iron Barr Marine unit:
1: overall view (exhaust inlet on the bottom right, water inlet above; exhaust outlet on the left)
2: 1/2" pipe elbow connected to the cast iron elbow
3: female thread on the exhaust elbow where #2 is connected
This is approx 20 years old with 600 hours on the engine.

HPIM1472.JPG HPIM1470.JPG HPIM1471.JPG
 
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