1964 390 overheating

[Keldridge]

We have been rebuilding a 1964 Thunderbird Convertible. The engine was rebuilt by a machine shop in Louisville, KY that is meticulous in every way. It has a new stock radiator and a new heater core. The car wants to overheat at an idle. We have tried different thermostats and two different clutch fans. One thermostatic, and now a centrifugal. We have checked the block with a Snap On Thermal Imager and it shows about 230 at the sender and would probably climb if we left it running. We have also installed a 14 inch Hayden thermostatically controlled fan to see if that would help and it has not. Any ideas? I'm starting to think a head gasket problem. Thanks

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[Hadderz]

Does sound like a fault I'm sorry to say. Those stock fans do work well - even better with the shroud but still good enough. Usually, the addition of an electric fan (presumed a pusher from the front) would provide that extra breeze - mine I used to turn on the heater but it never boiled over hence I think you may have an issue.

 

[66bluebird]

We have been rebuilding a 1964 Thunderbird Convertible. The engine was rebuilt by a machine shop in Louisville, KY that is meticulous in every way. It has a new stock radiator and a new heater core. The car wants to overheat at an idle. We have tried different thermostats and two different clutch fans. One thermostatic, and now a centrifugal. We have checked the block with a Snap On Thermal Imager and it shows about 230 at the sender and would probably climb if we left it running. We have also installed a 14 inch Hayden thermostatically controlled fan to see if that would help and it has not. Any ideas? I'm starting to think a head gasket problem. Thanks

I just figured out a overheat problem with my 66.
It was a faulty thermostat. It was a high flow Mr Gasket that broke in half and acted as a check valve in high flow situations. But usually recovered when idling. It was really hard to diagnose.
I know your problem is at idle but perhaps a non stock thermostat is causing your problem by flowing too much water? Be sure it is the stock size etc.

 

[74 Harley]

I think you need to pull the water pump, and pull the back cover plate off. The pump impeller may be loose or the vanes could be damaged.
So give us a little background on the motor, how many miles are on it? Any modifications? Are you burping the system when you fill it?

 

[Ward 57]

I just figured out a overheat problem with my 66.
It was a faulty thermostat. It was a high flow Mr Gasket that broke in half and acted as a check valve in high flow situations. But usually recovered when idling. It was really hard to diagnose.
I know your problem is at idle but perhaps a non stock thermostat is causing your problem by flowing too much water? Be sure it is the stock size etc.

Too much water flow would have the opposite reaction. I'd question the water pump. Many posts on the 'Y' block even with the newer design for increased flow still overheated due to the simple fact of a wrong gasket.

 

[Brax]

In my younger days my best friend bought a 64 t-bird 390 and it overheated no matter what was done to it turns out the former owner replaced the head gaskets and guess what he put one on backwards, the water jacket cut outs belong in the rear on both heads one side is installed upside down to the other to accomplish this, the other problem was 2 of the Welch plugs were pushed into the motor and left there when replaced at some point.

 

[SuperDave254]

Too much water flow would have the opposite reaction. I'd question the water pump. Many posts on the 'Y' block even with the newer design for increased flow still overheated due to the simple fact of a wrong gasket.

To much water flow and not enough cool air. I put a failsafe thermostat my my 390 fe and it worked great for a while but just this past week it got hot the thermostat stuck open like it's supposed to and then the water flowed to rapidly didn't have a time to cool on the radiator! I only learned this after I pulled over took the thermostat out cuz I thought it was vice versa and it got way hotter if that helps

 

[SuperDave254]

Sorry mine is a64 as well

 

[Ward 57]

To much water flow and not enough cool air. I put a failsafe thermostat my my 390 fe and it worked great for a while but just this past week it got hot the thermostat stuck open like it's supposed to and then the water flowed to rapidly didn't have a time to cool on the radiator! I only learned this after I pulled over took the thermostat out cuz I thought it was vice versa and it got way hotter if that helps

Never have heard of a stuck open thermostat causing over heating. Usually the problem being stuck closed. I would look towards a clogged radiator core. The flow is probably coming from the thermostat by-pass hose.

 

[SuperDave254]

Never have heard of a stuck open thermostat causing over heating. Usually the problem being stuck closed. I would look towards a clogged radiator core. The flow is probably coming from the thermostat by-pass hose.

Well sir... I say this with no disrespect just in case it comes out that way. ? The stat is in the circuit to stop water from circulation long enough for the fan, radiator, and all the other bells and whistles to cool the water before it starts it's journey though the fires of hell again. Now If the thermostat is not stopping the water and you're just circulating 500° water it's just the same as being stuck close well not as bad but... I'm not a "engine engineer" and for darn sure still getting tripped up on the 390FE

 

[Ward 57]

Well sir... I say this with no disrespect just in case it comes out that way. ? The stat is in the circuit to stop water from circulation long enough for the fan, radiator, and all the other bells and whistles to cool the water before it starts it's journey though the fires of hell again. Now If the thermostat is not stopping the water and you're just circulating 500° water it's just the same as being stuck close well not as bad but... I'm not a "engine engineer" and for darn sure still getting tripped up on the 390FE

Just the opposite. You are missing my point. High water flow through the radiator will keep the engine cool as designed. Removing the thermostat should make the engine run cold.
You are not getting the flow through the radiator. If you have access to a thermometer gun I'll bet the fins & tank on the radiator are colder than the rest of your engine.
The thermostat is closed when cold. When started the only flow is through the small bypass hose off the housing to help warm the engine and sometimes also piped to the heater core.
Once up to operating temperature the thermostat opens and lets hot water flow to the top of the radiator. When at running temp., the upper hose should be hot. If not water is not getting through the radiator.

 

[Brax]

Well sir... I say this with no disrespect just in case it comes out that way. ? The stat is in the circuit to stop water from circulation long enough for the fan, radiator, and all the other bells and whistles to cool the water before it starts it's journey though the fires of hell again. Now If the thermostat is not stopping the water and you're just circulating 500° water it's just the same as being stuck close well not as bad but... I'm not a "engine engineer" and for darn sure still getting tripped up on the 390FE

actually, it's the opposite of what you say the Thermastat stays closed so the engine heats up quickly, the way to test a Tstat is to place it in a pot of water warm the water slowly the Tstat should open fully by the temp stamped on it usually 160 for summer 180 for winter. If you remove the Tstat the car will run cold and never heat up to proper operating temp because the water is free flowing.

 

[TwoTires]

We have been rebuilding a 1964 Thunderbird Convertible. The engine was rebuilt by a machine shop in Louisville, KY that is meticulous in every way. It has a new stock radiator and a new heater core. The car wants to overheat at an idle. We have tried different thermostats and two different clutch fans. One thermostatic, and now a centrifugal. We have checked the block with a Snap On Thermal Imager and it shows about 230 at the sender and would probably climb if we left it running. We have also installed a 14 inch Hayden thermostatically controlled fan to see if that would help and it has not. Any ideas? I'm starting to think a head gasket problem. Thanks

I would suspect that there is an issue with water circulation caused by the water pump or an air pocket. You should be able to let it run, leaving the cap off and see a healthy water flow in the top tank of the radiator when the therm. is opening. I don't know the history of that engine, but some engines have an issue with air pockets that prevent proper circulation and require "Bleeding" to solve the issue.

 

[SuperDave254]

actually, it's the opposite of what you say the Thermastat stays closed so the engine heats up quickly, the way to test a Tstat is to place it in a pot of water warm the water slowly the Tstat should open fully by the temp stamped on it usually 160 for summer 180 for winter. If you remove the Tstat the car will run cold and never heat up to proper operating temp because the water is free flowing.

I am not disagreeing and really don't care if you believe or not I am telling you from my own experience on the 390FE in my 64 bird and a couple other beefier big block ford's for sure that once the water is hot it stays hot and does the engine if it does not have time to cool in the radiators. You do not have to even use the info I have given.... But when there are no other explanations for the reason why something is happening dig a little deeper and try something unwritten. That's the way old schoolers did it and I as well. Good day my friend!

 

[Ward 57]

I am not disagreeing and really don't care if you believe or not I am telling you from my own experience on the 390FE in my 64 bird and a couple other beefier big block ford's for sure that once the water is hot it stays hot and does the engine if it does not have time to cool in the radiators. You do not have to even use the info I have given.... But when there are no other explanations for the reason why something is happening dig a little deeper and try something unwritten. That's the way old schoolers did it and I as well. Good day my friend!

I beg to differ. Your understanding on how the radiator works is lacking. MORE flow cools the water better. It has been an issue with the baby birds and hence the introduction of higher flow water pumps for low speeds and RPMs. Either your radiator is too small or it is clogged with deposits. It can't cool if there isn't enough flow through it. It's called a radiator for a reason. It radiates heat. More coolant and air flow is the answer, They worked fine as designed from the factory.

 

[Brax]

I am not disagreeing and really don't care if you believe or not I am telling you from my own experience on the 390FE in my 64 bird and a couple other beefier big block ford's for sure that once the water is hot it stays hot and does the engine if it does not have time to cool in the radiators. You do not have to even use the info I have given.... But when there are no other explanations for the reason why something is happening dig a little deeper and try something unwritten. That's the way old schoolers did it and I as well. Good day my friend!

I have owned worked on rebuilt just about every ford motor from 21 stud v8 flathead’s to 429 boss motors to 3.8 grand national motors and have worked on 64 tbird 390s, simple pull out the T-stat and with a good radiator and water pump the car will never get to operating temp if it overheats it’s a problem with the motor there is no creative thinking about it, ford didn’t build cars that overheat, that goes for flatheads Y blocks FE 385 Windsor etc.

 

[Ward 57]

I beg to differ. Your understanding on how the radiator works is lacking. MORE flow cools the water better. It has been an issue with the baby birds and hence the introduction of higher flow water pumps for low speeds and RPMs. Either your radiator is too small or it is clogged with deposits. It can't cool if there isn't enough flow through it. It's called a radiator for a reason. It radiates heat. More coolant and air flow is the answer, They worked fine as designed from the factory.

I don't want to over analyze but when the engine is hot, check the temp of the lower radiator hose. It's the outlet back to the engine. If it's not really warm, flow is your issue. No flow through it. Could be as simple as an internally collapsed hose. Happens on brake lines too. There is a reason there is a configuring coil spring inside to prevent collapse as the water pump is trying to suck the water out of the radiator. Water flow is your issue. Either the rad or your hose.

 

[Rick Worth]

We have been rebuilding a 1964 Thunderbird Convertible. The engine was rebuilt by a machine shop in Louisville, KY that is meticulous in every way. It has a new stock radiator and a new heater core. The car wants to overheat at an idle. We have tried different thermostats and two different clutch fans. One thermostatic, and now a centrifugal. We have checked the block with a Snap On Thermal Imager and it shows about 230 at the sender and would probably climb if we left it running. We have also installed a 14 inch Hayden thermostatically controlled fan to see if that would help and it has not. Any ideas? I'm starting to think a head gasket problem. Thanks

can you run it with the cap off? If so can you see water flowing by the cap? Is the thermostat in correctly? IS the airflow HOT?

 

[SuperDave254]

I just figured out a overheat problem with my 66.
It was a faulty thermostat. It was a high flow Mr Gasket that broke in half and acted as a check valve in high flow situations. But usually recovered when idling. It was really hard to diagnose.
I know your problem is at idle but perhaps a non stock thermostat is causing your problem by flowing too much water? Be sure it is the stock size etc.

I agree 114%!!! My 64 390 would run good and sometimes hot as the devil's butt crack. Everyone here swears thermo stuck closed...I replace it with a fail safe thermo. Supposed to stick open if there is trouble. The next drive it is hot. Long story short. After 2 fail-safes that stuck in high flow, I learn that (and none of the elders here will believe me) In the 390 if there is no restriction to slow the water and give it time to cool in the radiator. It stays 220, 350, 490°. And I will put money on it!!!

 

[Ward 57]

I agree 114%!!! My 64 390 would run good and sometimes hot as the devil's butt crack. Everyone here swears thermo stuck closed...I replace it with a fail safe thermo. Supposed to stick open if there is trouble. The next drive it is hot. Long story short. After 2 fail-safes that stuck in high flow, I learn that (and none of the elders here will believe me) In the 390 if there is no restriction to slow the water and give it time to cool in the radiator. It stays 220, 350, 490°. And I will put money on it!!!

I must disagree, Fast water flow is in no way not have enough time to cool. Clogged radiator if original. You would not believe the crust that occurs internally over the years but you can still see flow when the cap is off. .