Trying to Stay Cool - FIXED!!!!

[HP2]

You certainly are trying all the correct things to improve temps.  The big variable seems to be how much crud may still be lodged in your block or if the previous owner actually performed mods to the block, like filler.

A few other thoughts...see if anyone in your area can test your coolant for combustion contamination. A compromised head gasket could be allowing both compression and exhaust pressure into the system, thus increasing its temp. A minor head gasket leak would not significantly impaact the engine when running nor be visible in the radiator but could elevate the temp. These by-products are captured in the coolant and there are ways to test for them.  Second thought, pulley ratios. What are the diameters of your upper and lower pulleys. If this ratio is off, then you can be under or over driving the coolant pump  and be creating either inadequate flow to remove the heat, or too much flow and causing cavitation which creates air pockets. Final consideration, impeller capability. I've noticed most water pumps these days are a/c units and its rare you can select an original none-a/c pump,. Impellers between the two are different in regards to how much coolant they push, but you might have an odler, non-a/c unit with fewer blades.  You could try riveting a backing plate to the impeller to provide better flow off the impeller.

[71vert340]

 So, I have to ask this question as it applies to coolant flow and temperatures. I notice that some of my water pump impellers have 6 blades and some have 8 blades. I would assume the 8 blade pumps more coolant  with the additional blades and it also has a larger diameter impeller. Is this correct? I understand one is used on A/C engines. I also understand belt pulley size can affect rpms and thus flow.  I assume one must consider this also.
Terry W.

[blown motor]

My 440 would run fine on the highway but when I got to town and puttered around it would get hot and not cool down on the way home. @Cudajason I know it sounds trivial but check your fan belt tension. Mine was a bit loose. I snugged it up and things have been fine.

[YellowThumper]

Spring or no spring in bottom hose?
Generally it is not necessary if whole system is properly functioning.
Suction side is just that. If radiator cannot flow what pump is pulling lower hose will collapse. Springs were a stopgap to prevent possibility.
Continue narrowing down possibilities.
Install the fan clutch as you already have it.
Purchase an infrared heat gun and check temps of coolant going in at the top and coming out at the bottom.

What pressure is your radiator cap? I recommend in the 15# range.
Is it a 22" or 26" radiator?
22" with a 360 is borderline capable from the start.
Mine with a 318 would idle all day long with zero issue. When changed to 360 (stockish) it would continually creep. Ended up going to a 26" to correct issue. Even with that, I kept the small core support opening. It still never overheated again. Can show what I did if you want.

Lastly, fill all gaps between radiator and core support with closed cell dense foam to force ALL air thru radiator. Even fill gaps between shroud and radiator.
I also concur with removing the hood scoop sealing plates. At low speed when you need all you can get for cooling this will help bleed off the trapped hot air.

[torredcuda]

" I had a lot of crud in the system.  The multiple flushing seemed to help, as the temp no longer went up on the highway.  I still have some crud in the system, but its much less.  You can see good flow in the rad with the car running and the cap off, so I don't think that is the issue."

It doesn`t take much crud to create a blockage and hot spot in the rear of the block, as I said I did multiple flushings and got out a lot of crud also but there was still a bunch behind the rear freeze plugs so I wouldn`t rule it out.

[70vert]

@YellowThumper I have a 22" OEM radiator in my 383 Challenger that now has a mild build 440. I rarely have any issues unless idling for a long time during the summer. And I'm in Houston, so HOT. I would prefer a 26" but not yet ready, or need to do that swap.

[YellowThumper]

@70vert  Auto or stick? An auto adds more heat as well.

@Cudajason you could also look into adding a remote trans cooler and removing the lines from front radiator.

[Scooter]

So, I have to ask this question as it applies to coolant flow and temperatures. I notice that some of my water pump impellers have 6 blades and some have 8 blades. I would assume the 8 blade pumps more coolant  with the additional blades and it also has a larger diameter impeller. Is this correct? I understand one is used on A/C engines. I also understand belt pulley size can affect rpms and thus flow.  I assume one must consider this also.
Terry W.

I replaced the stock pump on my 360LA with a Milodon HV a few months ago. Compared to the stock the only difference I could see was 1 extra paddle and the plate tacked over the paddles.

You might try ditching a clutch altogether. I had temp issues with the BB 390 in my Ford.

Tried a slew of different clutches and electric fans, neither worked.

Ended up with a Flex fan and 160 thermostat.

Drove it back from Reno a few weeks back in 97 degree heat.... stop and go up over Donner Summit and through Sacramento never saw the needle much over 180.

GL!

[Scooter]

@70vert  Auto or stick? An auto adds more heat as well.

@Cudajason you could also look into adding a remote trans cooler and removing the lines from front radiator.

^^ I'm planning on doing this to my 360~727 auto Challenger as soon as we get moved and settled. The only time I see the temp over 185 even in triple digit heat and traffic is when I'm climbing a grade.

Pretty sure the previous owner installed a torque converter with a stall too high and the friction is heating the motor. If an additional external cooler does not do it I'm going to have to replace the torque converter.

[71vert340]

So, I have to ask this question as it applies to coolant flow and temperatures. I notice that some of my water pump impellers have 6 blades and some have 8 blades. I would assume the 8 blade pumps more coolant  with the additional blades and it also has a larger diameter impeller. Is this correct? I understand one is used on A/C engines. I also understand belt pulley size can affect rpms and thus flow.  I assume one must consider this also.
Terry W.

I replaced the stock pump on my 360LA with a Milodon HV a few months ago. Compared to the stock the only difference I could see was 1 extra paddle and the plate tacked over the paddles.

You might try ditching a clutch altogether. I had temp issues with the BB 390 in my Ford.

Tried a slew of different clutches and electric fans, neither worked.

Ended up with a Flex fan and 160 thermostat.

Drove it back from Reno a few weeks back in 97 degree heat.... stop and go up over Donner Summit and through Sacramento never saw the needle much over 180.

GL!

I remember hearing /reading years ago that going to the pump impeller with more vanes and welding a plate to the impeller increased efficiency significantly. I was running a flex fan on my 74 Charger 360 with no overheating at all. I switched it recently to the clutch set up for a more stock appearance. If I have overheating problems, I'll reinstall the flex fan. I also removed my external transmission oil cooler when installing new transmission lines. I had no transmission problems for 15 years running just the external cooler. I've had the Radiator recored so I'll see how it goes in hot weather. I'll be keeping an eye on this thread to see what the final outcome is .
Terry W.

[70vert]

@70vert  Auto or stick? An auto adds more heat as well.

@Cudajason you could also look into adding a remote trans cooler and removing the lines from front radiator.

Mine is an Auto. Good idea to use an external trans cooler, would help 2 ways!

[Cudajason]

You certainly are trying all the correct things to improve temps.  The big variable seems to be how much crud may still be lodged in your block or if the previous owner actually performed mods to the block, like filler.

A few other thoughts...see if anyone in your area can test your coolant for combustion contamination. A compromised head gasket could be allowing both compression and exhaust pressure into the system, thus increasing its temp. A minor head gasket leak would not significantly impaact the engine when running nor be visible in the radiator but could elevate the temp. These by-products are captured in the coolant and there are ways to test for them.  Second thought, pulley ratios. What are the diameters of your upper and lower pulleys. If this ratio is off, then you can be under or over driving the coolant pump  and be creating either inadequate flow to remove the heat, or too much flow and causing cavitation which creates air pockets. Final consideration, impeller capability. I've noticed most water pumps these days are a/c units and its rare you can select an original none-a/c pump,. Impellers between the two are different in regards to how much coolant they push, but you might have an odler, non-a/c unit with fewer blades.  You could try riveting a backing plate to the impeller to provide better flow off the impeller.

@HP2   Again some great questions....The engine is mine, I rebuilt it in highschool with a few upgrades in the last few years.  No block filler etc. other then the crud that may still be in there.  If this does not work, I will look at cleaning it out again.

I have heard about the test strips for coolant, and ordered some to see if there are hydro carbons in the coolant.

I have done a compression test recently, and everything looked great., but I will check the coolant.

Pully ratios, hmmm, pulleys are stock as far as I know.  I have never changed them.

I have the water pump off two years ago, I do not recall seeing anything wrong with it, but if this does not work, I will look at an impeller

@70vert  Auto or stick? An auto adds more heat as well.

@Cudajason you could also look into adding a remote trans cooler and removing the lines from front radiator.

.

@YellowThumper - already running a trans cooler, not going through the rad

My 440 would run fine on the highway but when I got to town and puttered around it would get hot and not cool down on the way home. @Cudajason I know it sounds trivial but check your fan belt tension. Mine was a bit loose. I snugged it up and things have been fine.

@blown motor Interesting, I will be sure to check it out.

[Cudajason]

Spring or no spring in bottom hose?
Generally it is not necessary if whole system is properly functioning.
Suction side is just that. If radiator cannot flow what pump is pulling lower hose will collapse. Springs were a stopgap to prevent possibility.
Continue narrowing down possibilities.
Install the fan clutch as you already have it.
Purchase an infrared heat gun and check temps of coolant going in at the top and coming out at the bottom.

What pressure is your radiator cap? I recommend in the 15# range.
Is it a 22" or 26" radiator?
22" with a 360 is borderline capable from the start.
Mine with a 318 would idle all day long with zero issue. When changed to 360 (stockish) it would continually creep. Ended up going to a 26" to correct issue. Even with that, I kept the small core support opening. It still never overheated again. Can show what I did if you want.

Lastly, fill all gaps between radiator and core support with closed cell dense foam to force ALL air thru radiator. Even fill gaps between shroud and radiator.
I also concur with removing the hood scoop sealing plates. At low speed when you need all you can get for cooling this will help bleed off the trapped hot air.

@YellowThumper

yes spring in a rad hose.

I have an infrared temp gun and have verified the temps.  That being said, you can feel the difference in the car as teh temp creeps up and the performance just falls off, so its something I need to address.

the rad cap, is an 18# cap and a 22 in rad.

I have heard the comment about filling the gaps around the rad before, I will try that if this does not work too.

[Cudajason]

Well not exactly the result I was hoping for.

Took it out for a spin, nice day here, not supper hot, no humidity, and she was still hitting 210.  I would have expected cooler give the temps.

I verified the team with a temp gun.

the tamp is 30 degrees cooler at the bottom rad hose, so it would appear the rad is working.  no hot spots detected.

I also used a test strip, and that indicates the coolant is good, not hydro carbons.

I do think the  fan is a little to far out of the shroud now, so I may try a spacer to get that a little closer,

I think I will also try filing the gaps with some foam as @YellowThumper suggested.  Any suggestions on what foam to use?

[YellowThumper]

Sorry to hear.
Anything closed cell should be good so moisture doesn't absorb into it.
I have used varied stuff from Home stores.
Small gaps softer. Large gaps harder.
One I have had luck with that is thicker is the foam they use to insulate a/c lines for houses.
Hope that helps.