Overheating

Jakem

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Morning i have a 1975 campion boat with a ford 289 and it overheats when under load. The thermostat is not in the block it is iine from the heat exchanger to the hoses. One going to water pump.i dont think this is right.
 

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alldodge

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Not familiar with the design, but I would look on the raw water side first.
Has the impeller been changed?
What does the pump housing look like?

Place a piece of clear hose between the drive and heat exchanger to see if your sucking air
 

Jakem

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I havent seen thos configuration anywere. I dont beleive it is normal. I havent changed impeller yet i just got the boat. I have changed water pump, replaced end gaskets on heat exchanger, manifold elbow gaskets
 

alldodge

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The impeller should be the first thing done with a new boat
 

Jakem

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I will change it. I noticed the hose from drive to exchanger is really soft as well
 

Jakem

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Goodmorning can other people see this post. I cant seem to add one with pic on site
 

GA_Boater

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Good morning back. Your thread opening post has a photo.
 

kenny nunez

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It appears that you have a Mercruiser , if not post a picture of the drive. I recognized the Holley distributor. I only have seen them on Ford/Mercruiser 302 models.
 

Jakem

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I am getting air in the system and can't figure out why..I've changed hoses..clamps...water pump...impeller..ect..my fluid fills overflow and leaks it out top...however it isn't really hot....it will not drain back into heat exchanger...help
 

alldodge

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With the overflow filling I wonder if you have a blown head gasket
Post some pics of the motor hose routing to help me understand how its connected. I'm looking at manual 2 and want to compare
 

Jakem

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Hope this helps
 

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Jakem

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The rad cap that was on the boat when I got it was a 14 psi...is that normal?
 

Lou C

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It is possible that a blown or leaky HG is putting hot exhaust gas into the cooling water. You could get one of those carbon monoxide test kits to see if that’s the case; easier to determine with the closed system. We had a similar problem on a 98 Subaru EJ2.5 flat 4, these are known for blowing HGs. Symptoms were episodic overheating and bubbles/black residue in the recovery tank.
 

alldodge

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The HE doesn't look like the typical Merc design. The older design used 2 hoses coming in from the Thermostat housing to the front of the mans and 2 others coming back from the rear of the mans. I'm seeing what appears to be 3 hoses (maybe more) connecting to the top tank

Ford 888 closed cooling 302 _ 351.jpg
 

Jakem

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Ya it's odd how it's set up like that but the hx has a hole for a hose so I dunno
 

alldodge

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How many hoses go into the connection?

If more then 2, where do they come from?

Where do the thermostat hoses connect?
 

Jakem

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Thermostat has 2 coming out wich run to the bottom and back of exhaust manifold..that odd connection with 3 has 2 going to front of exhaust manifold and onesmaller one to water pump..and the main water.pump hose goes to bottom of heat.
 

alldodge

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The one coming from (flow toward) the water pump should go to the thermostat. If it did go to the water pump this would help flow into the block. With it going toward the mans reduces the flow into the block.

What does the thermostat housing look like?
 

Jakem

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Just the 2 hoses that run to back of the exhaust manifold. What should my heat exchanger look like.
 

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