1974 chrysler 318's fitted with fresh water cooling problem

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Nov 8, 2011
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I'm just wondering about the 318 Chrysler, my temp sensor was not working so I replaced it, seemed to be good, but now under full speed it goes up and reads 220, the manual says it should not be more than 200, I checked the water flow from the raw water pump and it looked good, I checked the water flow from the enclosed system and again it looked good, What I'm wondering is about the amount of water in the enclosed system, the holding tank which sits on top of the engine is almost level with the manifold's, This is the tank holding the antifreeze water, when I pulled the hose off the end of the manifold, without the engine running, no water came out, I would think there should be water there all the time, Should I remove the radiator cap and then start the engine, the water should draw down as it goes into the manifold, at that point add more water to fill the reservoir, what do you think, couldn't hurt or bad idea Thanks
 

GA_Boater

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Assuming the tank is also the heat exchanger;

If the hose you pulled off is supposed to be an antifreeze/water mix, then yes, running or not the hose should have coolant. If it's a seawater hose, then no water or very little unless the motor is running.

It might be worthwhile to check the thermostat and flush out the seawater side of the tank. Thermostat could be going bad and/or sand could be clogging the exchanger.
 
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Hi, thanks for the reply, There is no thermostat, yes the hose that I pulled off the end of the manifold should have contained the anti freeze mix, the hose is actually higher than the reservoir, the heat exchanger is below the manifold, The reservoir is where I would add water as needed, so I'm thinking if I remove the so called radiator cap, start the engine, the water will draw down in the reservoir as it fills the manifold, at which point I could add water to the reservoir and replace the cap, this extra water should help to keep the engine cooler,
 
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I checked the other engine for a thermostat and it had been removed, I'm assuming this engines thermostat has also been removed
 

Bondo

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Ayuh,...... Pictures sure would be nice on this one,..... Could be Alota things,....
 
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My main question is it a good idea to remove the radiator cap , and then start the engine, if the water in the reservoir draws down as I expect it will, is it going to cause any problem to add more water.
 

Bondo

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My main question is it a good idea to remove the radiator cap ,

It shouldn't matter, cap on, cap off, motor runnin' or not,....
 
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Thanks, I didn't think it would matter, but just wanted to ask, I can't be sure it is even overheating till I check it with the heat sensor gun, It doesn't act like it's overheating, runs just fine, but I thought it wouldn't hurt to have the manifolds full of water mix all the time and not having it drain back into the reservoir when the engine is off.
 

GA_Boater

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When the cap is off the tank and the motor off, is it full of coolant?
 
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Yes when the motor is off the reservoir is full of coolant, but pull the hose off the manifold when the motor is off and no coolant comes out, as it is slightly higher than the reservoir, that's why I'm thinking of having the cap off the reservoir starting the engine and I should see the level of fluid in the reservoir drop as it fills the manifolds, at which point I can add fluid to the reservoir, which will keep fluid in the manifolds after the engine is stopped.
 

GA_Boater

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A closed cooling system should be full at all times. This isn't making any sense, at least to me. The coolant is cooling the block and manifolds and needs to be full.

We need a couple of photos.
 

Ned L

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It sounds like what you are saying is there a 'bubble' of air trapped in the manifolds, because the surge tank is not the highest point in the system. I think your suggestion makes sense (though it shouldn't be necessary).
 
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