'70 Charger Overheats after 40 minutes on highway today [but before this it did not overheat at idle or shorter trips]

[RemCharger]

By the way, for clarification and confirmation, for your Charger 440, if you were facing the front bumper of the car, looking toward the windshield and steering wheel, where are your radiator inlet and outlet ports located?

For reference, my entrance (from thermostat) is upper right, and my exit (supplying water pump) is lower left.

Generally anything on the drivers side of a car is called left, passenger right.
Or, you can just say the whatever rad outlet is on the pass side, as example

 

[matchek]

Generally anything on the drivers side of a car is called left, passenger right.
Or, you can just say the whatever rad outlet is on the pass side, as example

Thank you RemC - corrected.

 

[1 Wild R/T]

As I mentioned in the other thread, swapping the water pump housing which initially seems like a good idea could lead to other problems, the timing marks on your later engine should be visible on the drivers side... Move the lower hose to the drivers side & reading the timing marks becomes difficult if not impossible...Unless your ready to swap the timing cover an damper at the same time...

Looks like your car came with a 22" radiator, you can see in the one photo that shows the passenger side of the top of the radiator the side panel extends about 2" inthe radiator area...

As far as re-coring the radiator you have, if anyone can find a place to do it cheaper than buying a new radiator I'd like to know where.. I had the numbers radiator for my R/T Vert re-cored eight years ago & it was over $700 then...

Besides, the radiator you have clearly came from a later vehicle... No reason to keep it...

What I would do? Go with a new 26" small block radiator for your car & replace those generic hoses... Looking at Rock Auto I believe these hoses should work... They are for a 73 Charger with a 440... Which uses the water pump housing you gave and a 26" radiator...

GATES 21034
GATES 20875

 

[matchek]

As I mentioned in the other thread, swapping the water pump housing which initially seems like a good idea could lead to other problems, the timing marks on your later engine should be visible on the drivers side... Move the lower hose to the drivers side & reading the timing marks becomes difficult if not impossible...Unless your ready to swap the timing cover an damper at the same time...

Looks like your car came with a 22" radiator, you can see in the one photo that shows the passenger side of the top of the radiator the side panel extends about 2" inthe radiator area...

As far as re-coring the radiator you have, if anyone can find a place to do it cheaper than buying a new radiator I'd like to know where.. I had the numbers radiator for my R/T Vert re-cored eight years ago & it was over $700 then...

Besides, the radiator you have clearly came from a later vehicle... No reason to keep it...

What I would do? Go with a new 26" small block radiator for your car & replace those generic hoses... Looking at Rock Auto I believe these hoses should work... They are for a 73 Charger with a 440... Which uses the water pump housing you gave and a 26" radiator...

GATES 21034
GATES 20875

Thank you Wild! I totally agree. I bought a new thermostat (I got the one for racing - it is supposed to be stable). And I found a new radiator - it is a 26 " and it called a "small block 26" but it looks like the same 26" for the big block just that the ports are reversed. Thank you totally agree!

By the way, what did you mean by the 22" inch statement ? I don't follow. Not sure how you can tell it came with a 22". My car came with a 318 from the factory and those cars came with either a 19" with no A/C and 26" with A/C.

 

[matchek]

As I mentioned in the other thread, swapping the water pump housing which initially seems like a good idea could lead to other problems, the timing marks on your later engine should be visible on the drivers side... Move the lower hose to the drivers side & reading the timing marks becomes difficult if not impossible...Unless your ready to swap the timing cover an damper at the same time...

Looks like your car came with a 22" radiator, you can see in the one photo that shows the passenger side of the top of the radiator the side panel extends about 2" inthe radiator area...

As far as re-coring the radiator you have, if anyone can find a place to do it cheaper than buying a new radiator I'd like to know where.. I had the numbers radiator for my R/T Vert re-cored eight years ago & it was over $700 then...

Besides, the radiator you have clearly came from a later vehicle... No reason to keep it...

What I would do? Go with a new 26" small block radiator for your car & replace those generic hoses... Looking at Rock Auto I believe these hoses should work... They are for a

Thank you so much for the part numbers too!

 

[matchek]

FYI it looks like I have Chrysler water pump housing 3698468 which is supplied from the passenger side. Other here mentioned their housing is on the drivers side. The drivers side water pump has many new option for sale but I can't find any new 3698468. It looks like Dodge changer the water pump set up in 1973 but not sure why these are so much harder to find.

 

[RemCharger]

FYI it looks like I have Chrysler water pump housing 3698468 which is supplied from the passenger side. Other here mentioned their housing is on the drivers side. The drivers side water pump has many new option for sale but I can't find any new 3698468. It looks like Dodge changer the water pump set up in 1973 but not sure why these are so much harder to find.

If that were my car, I'd put it back to stock drivers side pump and fairly correct radiator.

But if you're staying with what you have, clean your rad and get a flow kooler pump.
I see no reason to find or replace the whole housing. It's just a chunk of cast iron.

 

[matchek]

If that were my car, I'd put it back to stock drivers side pump and fairly correct radiator.

But if you're staying with what you have, clean your rad and get a flow kooler pump.
I see no reason to find or replace the whole housing. It's just a chunk of cast iron.

I would be open to it and I looked into it, but not sure if because this is an Oct 1972 block, but there is not a lot of room on my drivers side near the bottom of the radiator. With the pully and oil filter looks like it would be tight to have the water pump be supplied on the drivers side with my engine if at all. Some other folks have my set up too but have not heard why. The passenger side water pump is an original Chrylser part. Champion Radiators makes a 26" radiator with my port set up - my hunch tells me the intent of this setup is for if you had a 318 with air conditioning. I wound up buying a new radiator. The 26" radiator that I ordered is the same size as design as the big block radiator - the only difference is the radiator ports are reversed.

 

[matchek]

I was wondering what temperature should you expect to get with the thermostat removed? I bought a brand new radiator and plan on having it installed next week, but I am in the process of flushing and cleaning out the old one while it is being shipped to potentially save as a spare. After draining and flushing the radiator and now running thermocure though it with the thermostat removed, I get 170F at the dash gauge and 165 to 171F with a thermometer gun pointing at the block sensor (Ambient Temperature is 72F). I get around 165F at the radiator inlet and 150F at the radiator outlet. I was expecting temperature more like 130 to 140F without the thermostat. The manual mentions that you should not use a 160F thermostat and turns out if I used one it would just be open all the time! What water temperature should you expect while running the car at idle withouth a themostat in a clean system?

Oncle I flush out the thermocure today and tomorrow, I plan on installing a new "Race" 180F thermostat. This more expensive thermostat is supposed to be more stable. Hopefully it is okay for regulator driving. It was times the cost.

 

[AFD 792]

Possible missing spring in lower radiator hose? Keeps the hose from collapsing at higher rpm

 

[matchek]

Possible missing spring in lower radiator hose? Keeps the hose from collapsing at higher rpm

Hi AFD, that is a good point, in addition to the murkey corroded tubes in the old rad. When I pulled off the upper hose yesterday, around 5 inches of the 18 inches of the springs were missing because it just rusted and broke off. The lower hose looke great on outside but the springs may look rusty on the inside of that one too.

I ordered the lower hose and plan on picking up today.

 

[Purepony]

I’d Start with the thermostat some new hoses since you’re already in there and new radiator cap.

If that doesn’t solve the issue, I’d do water pump after that and then the radiator last

 

[matchek]

I’d Start with the thermostat some new hoses since you’re already in there and new radiator cap.

If that doesn’t solve the issue, I’d do water pump after that and then the radiator last

I agree, I am doing all these things. As an update, when I looked closer inside the radiator, I saw several tubes partially clogged with crud. I only had the car for two years and it is likely the current radiator is decades old. Since I found a new radiator for only $305, I ordered it and plan on replacing it next week if it fits. In the meantime, I am cleaning out the old one (running Thermocure through it) and will either use it if the new one doesn't fit or keep it as a spare just in case.

 

[Don Frelier]

I was wondering what temperature should you expect to get with the thermostat removed? I bought a brand new radiator and plan on having it installed next week, but I am in the process of flushing and cleaning out the old one while it is being shipped to potentially save as a spare. After draining and flushing the radiator and now running thermocure though it with the thermostat removed, I get 170F at the dash gauge and 165 to 171F with a thermometer gun pointing at the block sensor (Ambient Temperature is 72F). I get around 165F at the radiator inlet and 150F at the radiator outlet. I was expecting temperature more like 130 to 140F without the thermostat. The manual mentions that you should not use a 160F thermostat and turns out if I used one it would just be open all the time! What water temperature should you expect while running the car at idle withouth a themostat in a clean system?

Oncle I flush out the thermocure today and tomorrow, I plan on installing a new "Race" 180F thermostat. This more expensive thermostat is supposed to be more stable. Hopefully it is okay for regulator driving. It was times the cost.

I think 165 is kinda high for no thermostat.
I think my Plymouth was probably closer to 140 with no thermostat.
Have you dumped the contents with the thermocure?
How does it look?

 

[matchek]

I think 165 is kinda high for no thermostat.
I think my Plymouth was probably closer to 140 with no thermostat.
Have you dumped the contents with the thermocure?
How does it look?

I agree - 140F sounds about right to me too. It actually fluctuates between 165 and 170 with no stat according to the thermo gun (170 instrument gauge). I ran Thermocure in it yesterday and today and will drain it tomorrow.

 

[matchek]

Okay so I am done flushing and cleaning out the cooling system. In addition I installed a Mr. Gasket Hi Performance 180 F thermostat. Green fluid is when I first drained the coolant. The black fluid is after I drained and flushed the radiator and filled the system with tap water and "Thermocure". Ran the engine for around 1.5 hours over two day. The black fluid is after I drained the Thermocure. The clear water is after I fully flush the system for around 15 minutes. Filled with distilled water only (not coolant) and ran for 30 minutes - the temperature gauge pegged at around 185F. With the temperature gun with the heater off, at the temp sensor is around 173F, Radiator inlet 174F, Outlet 160F. With the heat on: Sensor 172F, inlet 168F, outlet 163F., Note this value flucuate around +/-5 F as I keep the gun. But all along the temp gauge at the dash is around 180 to 185 depending on if I have the heat on.

I looked inside the radiator and it looks a lot better. This Thermocure is great if you haven't cleaned it in 5 to 8 years or so but my rad is probably 20 to 30 years old. Maybe if I drove around for several weeks it would be even better. It looks a lot better BUT the tube aren't perfect. My new radiator is coming tomorrow and hopefully it fits. Note: I did not take it on the highway - just idled it in my driveway. I will know more next week after the new rad install.

 

[matchek]

I plan on having the new radiator installed this week. After the flush, at idle, it runs at 185F similar to before. I have not taken it on the highway yet - I don't plan on doing that until after the new radiator install.

Even when I was cleaning the cooling system with Thermocure, and the fluid was black, I idled the car in the driveway, for 45 minutes with the heat on and off, with the hood up and down, and the temp gauge was solid at 185F.

As a recap, before the radiator flush, at idle, and the driving for around 35 miles at 60 to 80 mph, the temperature was fine ( ~ 190F) and then after I drove 3 or 4 miles at 55 mph when I went down a different road, the temperature gauge went from 190F to 230F over 5 minutes and then went to 250F when I exited the highway and sat at the light - after the light I turned it off for 35 minutes before driving the last one mile home. I started and idled it the next day and the temp was fine (at idle - did not drive on the highway).

I plan to have a new radiator installed this week even though I cleaned the old one. As a reminder, I had the carburetor removed and cleaned and the idle mixture screws adjusted. It runs smooth and does no backfire. The mechanic thought it was the best running Mopar he has seen. If the new radiator does not solve the overheating, do you think I could have a faulty carburetor (heard when the carb is not putting the right fuel the car can overheat). But how likely it could be the carb when the car is running fine and no stumble? Why the carburetor cause an overheating problem at high speeds but not at idle? Was interested in your carb thoughts. The mechanic is already prepping me that the new radiator may not solve the problem. The only other thing is a new water pump (I can see water moving the radiator - just pulling straws).

 

[HawkRod]

I plan on having the new radiator installed this week. After the flush, at idle, it runs at 185F similar to before. I have not taken it on the highway yet - I don't plan on doing that until after the new radiator install.

Even when I was cleaning the cooling system with Thermocure, and the fluid was black, I idled the car in the driveway, for 45 minutes with the heat on and off, with the hood up and down, and the temp gauge was solid at 185F.

As a recap, before the radiator flush, at idle, and the driving for around 35 miles at 60 to 80 mph, the temperature was fine ( ~ 190F) and then after I drove 3 or 4 miles at 55 mph when I went down a different road, the temperature gauge went from 190F to 230F over 5 minutes and then went to 250F when I exited the highway and sat at the light - after the light I turned it off for 35 minutes before driving the last one mile home. I started and idled it the next day and the temp was fine (at idle - did not drive on the highway).

I plan to have a new radiator installed this week even though I cleaned the old one. As a reminder, I had the carburetor removed and cleaned and the idle mixture screws adjusted. It runs smooth and does no backfire. The mechanic thought it was the best running Mopar he has seen. If the new radiator does not solve the overheating, do you think I could have a faulty carburetor (heard when the carb is not putting the right fuel the car can overheat). But how likely it could be the carb when the car is running fine and no stumble? Why the carburetor cause an overheating problem at high speeds but not at idle? Was interested in your carb thoughts. The mechanic is already prepping me that the new radiator may not solve the problem. The only other thing is a new water pump (I can see water moving the radiator - just pulling straws).

Respectfully, I think you are overanalyzing.

A very lean running engine can cause heat issues. But you have already seen a good improvement based on cleaning out the cooling system. I'd put the new radiator in it and drive it. My bet is the overheating problem has been solved. If not, then we can start to think about other issues based on the symptoms it has.

Good luck and I hope your issues are behind you.

 

[matchek]

Respectfully, I think you are overanalyzing.

A very lean running engine can cause heat issues. But you have already seen a good improvement based on cleaning out the cooling system. I'd put the new radiator in it and drive it. My bet is the overheating problem has been solved. If not, then we can start to think about other issues based on the symptoms it has.

Good luck and I hope your issues are behind you.

Thanks I agree. I think it is farfetched but thought I would ask. I have never been in a classic car where it ran well but it overheated due to carburetor but thought I would ask . My current mechanic thinks driving 78 mph in this Charger and I need to slow down. On the 35 mile trip, I drove around 78 mph for around 5 miles.

 

[HawkRod]

Thanks I agree. I think it is farfetched but thought I would ask. I have never been in a classic car where it ran well but it overheated due to carburetor but thought I would ask . My current mechanic thinks driving 78 mph in this Charger and I need to slow down. On the 35 mile trip, I drove around 78 mph for around 5 miles.

When I drove my 70 Road Runner across country in 2015 we drove sustained speeds of 90+ MPH through Kansas with a top speed of 108 MPH. Our 90+ speeds lasted about 2 hours or so. There is no reason, from a cooling system perspective, that your car shouldn't be able to do the same.