Overheating issues

-
phaelax

phaelax

Well-Known Member
Joined
Sep 3, 2014
Messages
437
Reaction score
149
Location
Ohio
I have a 440 with a 26" aluminum radiator plus a 2L overflow expansion. It does have a fan shroud (thanks to whoever I bought that from last year on the forum) and a flex fan. Car overheats even just idling when its only 60 degrees outside. After just a few short miles it'll easily reach 200+ degrees and would continue over 220 if I allowed it.

I flushed the radiator out several times with a hose and let it run a bit just to try and get out anything that might be in the block. Refilled with coolant and distilled water. Also replaced the water pump with a high flow flowkooler and one of their thermostats. So far nothing has helped at all. A local shop let me use their block tester and assuming I used it correctly didn't shown any signs of a leak. When I flushed the radiator outside of the car, I get clean water passing through it within seconds, I really don't think the radiator is the problem but I have a radiator shop that says they'll clean it out and inspect it for about $150. I'm not sure where to go from here.
 
Last edited:
Is your hood to radiator support seal in place? How about your lower cowl to radiator support seal? Without these seals in place, air can and will just flow over and under the radiator instead of getting trapped in front of it and being vacuumed through it. Kind of like drinking through a straw with a hole in it. Could also be a timing issue, or a partially clogged radiator. What thermostat are you running?
 
Does it cool down at speed, like going down the highway. Who made the alum rad and do you know how many rows it is and how large the rows are. Also whats the details on the engine, CR, fuel injection vs carb, what PSI cap are you running on the rad, what ratio of coolant to water are you running?

There is a reason there are hundreds of threads on this with thousands of replys.
 
What are your pulley diameters (crank and water pump)

Are you running v belts or a serp belt?

Where is your timing, at idle, at speed?
 
FYI, Check the lower rad hose. Does it have a spring in it ?
Possible the hose is collapsing. Had this happen on a 451 stroker. All new parts but would still overheat.
Made a coil from a coat hanger installed it in the hose, problem solved. My 2 cents.
phaelax said:
water pump with a high flow flowkooler
Click to expand...
 
Shoot the top and bottom rad fittings, not the hose, with a temp gun.
Your rad needs to shed 50* to be adequate, 30* is very marginal, don't play in traffic.
If it's not shedding enuff, shoot areas of the rad, about 1/2 way down, all across, - cool/cold areas are plugged tubes, the more/bigger the cool area, the bigger your problem .
You might pick up some info if you search "overheat", this subject is flogged to death every Spring.
Good luck .
 
Last edited:
It's a stock 440 '78 block with a mild cam upgrade (compcam 21-223-4) Fuel injected with sniper kit, but issue existed beforehand when I had a quickfuel 750cfm carb on it.

Thermostat: Robertshaw 370-160 Series hi flow thermostat
Pump: MOPAR Big Block hi flow water pump

Radiator cap is 16 psi.
Coolant is a 50/50 blend with distilled water.
Lower hose doesn't have the coil in it, but it doesn't look like it collapses when hot. (i can double check tomorrow)
Just replaced the belt a few weeks ago actually, old one was showing cracks.

As far as the radiator goes, I don't know anything about it. Was in the car when I bought years back but it managed to handle the older 440 that had over 500hp and was cooling the current block I have until about a year ago.

Moving does not improve the temperature, at best it slows it from increasing marginally.

Is your hood to radiator support seal in place? How about your lower cowl to radiator support seal?
Click to expand...
I've never had any such support seals on this car ever. I never even had a fan shroud until recently and I only put that one because the overheating started, but years after I've had the car.

I have a temp gun somewhere, I can look for that tomorrow too.
 
How about your pulley diameters
Is it v belt or serp belt.

These are real trouble shooting questions.
 
While your at it, post some pictures of your set up. Fan, shroud, rad, hoses and such.
 
Put a spring in the lower hose measure crank and pump pulley diameters and what fan blade are you running? It’s not a 5-blade for the Magnum engines is it?
 
It's a v-belt. I have no idea about the pulley sizes, most likely whatever was stock in 1978

image0.jpeg


image1.jpeg


image2.jpeg
 
I’d lose that fan, get “at least” a MP 5-blade asymmetric. Or a 6 or 7 blade. No flex fan. Gotta measure the pulleys. As close to 1:1 ratio. Definitely don’t want a small crank pulley (under driven) with a larger wp pulley. Should be the the same diameters essentially
 
I could have sworn I posted asking about what thermostat it has?
 
phaelax said:
What's wrong with the one I have?
Click to expand...
There’s much posted on this forum to learn about them. I would do a search for any pros and all the cons. I run factory style stiff blade clutch fans.
 
So what we know so far...

  1. Current rad setup worked fine with older 440
  2. Engine heats up at idle
  3. Engine heats up at speed
  4. Problem started about a year ago.
Question

  1. Did the old 440 have the same pulleys and fan on it when it worked properly?

Indications:
Overheats at idle and speed says it is not an airflow issue.

Go back and be sure the water pump you bought is the correct rotation. Water pumps designed for serp belts typically rotate backwards

If it's not an airflow problem then it is a coolant flow issue or something else.

Things that restrict coolant flow
  1. Bad water pump
  2. Incorrect water pump
  3. Wrong sized pulleys
  4. Stuck thermostat
  5. Debris buildup in the block
  6. Debris in the water passages.
  7. Wrong gaskets
Other things that increase tem in an engine

  1. Timming
  2. Cracked block
  3. Excess overbore
  4. Trapped air
 
has it always run hot or is this a new and sudden issue?

NM, RIF...
 
phaelax said:
I linked to the thermostat in a post above.
Click to expand...
Ok my bad. I wonder where my original post went? Oh well. What water pump housing does it have? 440 Source had some improperly machined with the inlet to the water pump being way too small.
 
What is the initial timing?
Lean mixture causes high temps.
 
Just a thought
With the radiator cap open, car running, thermostat open. Do you see a good flow of coolant running inside the rad?
Ive got the same water pump as you. I run a 3 core 26'' rad and when and it looks like the Niagara rapids inside my rad
Could be a lot of issues others mentioned but as someone said your rad could be partially blocked
 
As stated, lose the "flew fan" and get at least a 5 blade fixed fan with a fan clutch. Those flex fans are a recipe for disaster, they crack at the blade mounting points and will shred a radiator in a heart beat. (Ask me how I know).
 
  1. Did the old 440 have the same pulleys and fan on it when it worked properly?
Click to expand...
All but the fan. It had a clutch fan but I think it was bad if I remember right.


Go back and be sure the water pump you bought is the correct rotation. Water pumps designed for serp belts typically rotate backwards
Click to expand...
I only replaced old one (which worked originally for years) because I started having issues. Figured trying the high-flow wouldn't hurt anything.

I don't know what the timing is at.

I drove a couple miles and got stuck at a really long light, car hit 230 by the time I got back in the driveway. Popped the hood, pressure was too much for the overflow tank, it was starting to seep out from the cap. Top and bottom hose looked fine but as it cooled down they both collapsed (first time I've seen that, but also my car isn't normally at 230 before I turn it off).

Started the car back up after awhile and let it reach 190+, hoses were not collapsing. I found my temp gun and I checked temps on the radiator. Got the gun as close as I could and temps ranged from 95 to 165. One side seemed to be about the same temp at the top and bottom.

I can squeeze the bottom hose and hear fluid immediately come back up to the top to the overflow so I'd say it doesn't seem blocked but then I don't really know how it flows on the inside either. I can remove it and take it to the shop in the morning if you guys think I should.
 
This is just out there as a shot.
I had a waterpump that the blades were stripped from the shaft.
Externally all looked fine but the blades didn't turn at the same speed as the engine causing the overheating.
I ended up buying the car because no one could figure it out. Look in the rad with cap off and you would see the coolant moving.
Put the cap back on and temps would rise and over heat before you got 2 blocks.
This is just a guess.
 
If you could get a temp at the top and bottom hose fittings, preferably, but the hoses will suffice.
With the top hose being 200*? at the top going into the rad, it needs to be 150*-ish coming out the bottom fitting, shedding 50*s, that'll work, and rad is doing it's job., look elsewhere.
If coming outta bottom hose at 175*+ is troublesome, and rad isn't doing is job, good place to start.
Logical process of elimination.
Don't chase complicated,vague stuff before fundamentals, that can be costly and disappointing.
Read some previous years "overheat" to view frustration, perhaps have fewer " frisbees " in your future .
Good luck .
Perhaps check the temp at the top/bottom hoses of your daily driver for reference.
 
Last edited:
You must log in or register to reply here.
-

Back
Top