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ealry 60's Chrysler 318 cooling problems

asrotolo

New member
Hello,
I have a recently rebuilt early 60's model Chrysler marine 318 with a fresh water cooling system. This particular engine has the thermostat housing with the choke t-stat and pressure relief disc. The engine is running hot, and I can't seem to figure out why. I would like to replace the t-stat housing as it is corroded, but I cannot find any of this type. I have tried to bleed all the air from the system, but that has not helped. It is hard to tell if I am getting good cooling in the heat exchanger or proper circulation. The fresh water pump dual impellers were ok when installed recently, and it seems I am getting good flow on the seawater side.

I am running out of ideas. Does anyone have any suggestions?

Thanks in advance!
Tony
 
Ayuh,.... My 1st guess is the raw water pump, ain't pumpin',.....

Pull the raw water feed hose of the HE, 'n See if it's pushin' water,....
Then make sure the used raw water can escape,...
 
Ayuh,.... My 1st guess is the raw water pump, ain't pumpin',.....

Pull the raw water feed hose of the HE, 'n See if it's pushin' water,....
Then make sure the used raw water can escape,...


Thanks for the response!

Yesterday I pulled the seawater pump and checked the impeller. All good…
I also flushed from the downstream side of the pump through the HX and out of the exhaust. All lines are clear…

When I ran the boat in the water Friday, I could see the water swirling in the suction strainer for the seawater pump, but I will confirm that again today with a hose.

I also plan to pull the impellers of the fresh water pump (it has 2 in a single pump housing). They were good when I installed them, but after several weeks of troubleshooting, I suppose it would be good to check them since I know that I had lots of air in the closed loop system.
 
When I ran the boat in the water Friday, I could see the water swirling in the suction strainer for the seawater pump, but I will confirm that again today with a hose.

Ayuh,.... Start the motor, then pull the raw water inlet hose, off the heat exchanger, 'n hold it pointed straight Up,....
At idle, the stream of water should rise 5" or 6", before it topples over upon itself,....

Any vacuum leaks in the raw water pump, or the pipin' leadin' into it, will cause air to be sucked into the coolin' water,.....
 
Ayuh,.... Start the motor, then pull the raw water inlet hose, off the heat exchanger, 'n hold it pointed straight Up,....
At idle, the stream of water should rise 5" or 6", before it topples over upon itself,....

Any vacuum leaks in the raw water pump, or the pipin' leadin' into it, will cause air to be sucked into the coolin' water,.....

A leak in the gasket of the cleanout port on the strainer a common cause of overheat problems. A mason jar seal with the tab cut off is a good replacement for some strainer cleanout ports. Some cleanout ports can be installed "kittywampus" and cause vacuum leaks and overheating.
 
Hello,
I have a recently rebuilt early 60's model Chrysler marine 318 with a fresh water cooling system. This particular engine has the thermostat housing with the choke t-stat and pressure relief disc. The engine is running hot, and I can't seem to figure out why. I would like to replace the t-stat housing as it is corroded, but I cannot find any of this type. I have tried to bleed all the air from the system, but that has not helped. It is hard to tell if I am getting good cooling in the heat exchanger or proper circulation. The fresh water pump dual impellers were ok when installed recently, and it seems I am getting good flow on the seawater side.

I am running out of ideas. Does anyone have any suggestions?

Thanks in advance!
Tony
Hey Tony, any luck with your overtemp issue. I’m having a similar problem and was curious if you found a solution.

Russell
 
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