351 Cleveland Overheating Issued

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205-210 is not "hot", that's normal operating temperature. Thermostat ratings do not dictate the running temperature of the engine, that is simply the opening temperature.

https://knowhow.napaonline.com/temperature-control-engine-thermostat-testing-tips-and-tricks/

Factory spec radiator cap is 13psi, so the system will pressurize to that amount before it begins to vent. If it's not pushing coolant out the overflow, then I would put some miles on it to let the break-in process begin.
 
Spike Morelli said:
I believe the head gaskets are self-explanatory, as there is a big square water passage at the front on both head and deck surfaces., on the Clevelands. Usually, when installed correctly, a small tab of a corner of the head gasket will be sticking out at the lower front corner of the head. The photos below show in the 1st picture (open the photo) with no square opening at top right of block, this is the left, or driver's side, and the square opening is just out of frame to left. 2nd photo clearly shows right side of block with square water opening. You can hardly get these gaskets on wrong. Back when I was doing service work, if a customer came in with an overheater, amongst all the things we would do to check, was bring the vehicle up to temp with the cap off and put a thermometer in the radiator coolant to double check the gauge. It's usually a combination of radiator, water pump , shroud, thermostat, gauge, coolant mix, radiator cap, timing check, while looking at the system. Of course, a block at .060" over can heat up too.
Click to expand...
Thanks for sending. I will check temp with thermometer against the gauge. Water pump is new and working, coolant is mixed 50/50, will look into the cap, I do have the fan completely inside the shroud?? Thermostat is correct but a 180. Looking for a 195 with the “hat”. Hard to find.
 
Hemikiller said:
205-210 is not "hot", that's normal operating temperature. Thermostat ratings do not dictate the running temperature of the engine, that is simply the opening temperature.

https://knowhow.napaonline.com/temperature-control-engine-thermostat-testing-tips-and-tricks/

Factory spec radiator cap is 13psi, so the system will pressurize to that amount before it begins to vent. If it's not pushing coolant out the overflow, then I would put some miles on it to let the break-in process begin.
Click to expand...
Thanks. I get nervous when approaching 210.. my 65 ran around 215-220. Always gave me anxiety!!
 
giantpune said:
The radiator hose getting firm, does it do that when you crank the engine up cold, or only after it warms up?

And what happens when you run the engine with no radiator cap? Whatever was pressurizing the hose should come out the radiator opening. Is it coolant or is it combustion gases?
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Gets firm with cap on and only after it warms up. Nothing noticeable comes out of the radiator opening.
 
With your descriotion of the upper radiator hose being hard as a rock, or words to that effect, I would suggest running a Block Check test. You can rent or purchase a Block-Check kit from most parts stores. I have a video on how to perform a Block-Check on our 1973 Mach 1, but it is applicable to pretty much any automobile with a gasoline or even diesel engine. My YouTube video is at the following address:

https://youtu.be/OhNQVEp7Kxw

That said, before going to far down the road I suggest you varify the accuracy of your temp gauge by using a digital infrared thermometer. They are inexpensive. I aim ours at the upper radiator at a distance of 6-12 inches. If it turns out your temp gauge is over-reading you can do tests on the sending unit and.or gauge while looking for an electrical issue. I normally find the sending unit is inacurrate.
But! If you replaace the sending unit get the corect type. There is one for idiot light systems,a nd another for temp gauges. One of the nearly as common causes of over-reading is a faulty Instrument Voltage Regulator (IVR). Attached is a file you can refer to re: how to do the electrical tests on the IVR, as well as other electrical tests you can and should perform before changing parts left and right.

Once you find and repair the issue I hope you post a followup so I and others can see what you found,
 

Attachments

  • 1973Ford_FuelOilTemperatureGaugeCircuitryShopManualInformation_20240530.pdf
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Fan placement does matter, but doubt it'll make or break you as far as running too hot. I've always been told the fan should be just inside the opening to get the most effective draw of air through the radiator.

Another thought might be timing - retarded timing or very low initial timing can make you run hot too.
 
What type of fan blades do you have? Is it solid or does it have the clutch? Is it for a 351C, do you have A/C, is it on when it’s running hot? Your fan blades should be into the shroud around 50-70% last time I looked depending on your blade configuration. I didn’t see in your posts whether the rad was cleaned out or if it’s new. If you added hp to your engine you may need more cooling capacity. Visit West Coast Classic Cougar website and click on his videos. He does a pretty good job explaining how good our original rads are and what you need to do to keep them up to snuff.
 
Last edited:
mrgmhale said:
With your descriotion of the upper radiator hose being hard as a rock, or words to that effect, I would suggest running a Block Check test. You can rent or purchase a Block-Check kit from most parts stores. I have a video on how to perform a Block-Check on our 1973 Mach 1, but it is applicable to pretty much any automobile with a gasoline or even diesel engine. My YouTube video is at the following address:

https://youtu.be/OhNQVEp7Kxw

That said, before going to far down the road I suggest you varify the accuracy of your temp gauge by using a digital infrared thermometer. They are inexpensive. I aim ours at the upper radiator at a distance of 6-12 inches. If it turns out your temp gauge is over-reading you can do tests on the sending unit and.or gauge while looking for an electrical issue. I normally find the sending unit is inacurrate.
But! If you replaace the sending unit get the corect type. There is one for idiot light systems,a nd another for temp gauges. One of the nearly as common causes of over-reading is a faulty Instrument Voltage Regulator (IVR). Attached is a file you can refer to re: how to do the electrical tests on the IVR, as well as other electrical tests you can and should perform before changing parts left and right.

Once you find and repair the issue I hope you post a followup so I and others can see what you found,
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This is fantastic. Thanks for the link and the learned knowledge. As soon as I have a resolution, I’ll be sure to post the outcome. Thank you again.
 
MattCoppola said:
I’m hoping it’s not a blown or cracked head gasket. The top hose gets awfully hard and very hot??
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I'm not convinced you have to be concerned with your current temperature. If you are stock/near stock with a safe tune your most likely totally fine. However, if you're well built and making good power I'd cool that water temperature down.
 
Cleveland Crush said:
I'm not convinced you have to be concerned with your current temperature. If you are stock/near stock with a safe tune you’re most likely totally fine. However, if you're well built and making good power I'd cool that water temperature down.
Click to expand...
I kept it stock. Nothing fancy… yet Thanks
 
MattCoppola said:
Running at 212 seems so hot to me
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In addition, today's clean fuel blends often don't play well with our vintage V8's original tune requirements from the early 1970's. Those old
specs were based on leaded regular at about 90 octane and premium at 96+ octane.
 
All depends Matt...timing curve, dynamic compression, cam, a/f readings, etc, etc...Start with "Premium" and see how it runs then try working your way down to mid grade or even regular unleaded. Ton of variables effect fuel requirements.
 

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