Technical Overheating head scratcher

Good enough.

 

I would suggest trying another water pump. I just replaced one where the impeller was loose and spinning on the shaft. I had installed it during an engine rebuild and the engine ran a little warm but didn't overheat. Eventually it got to the point where it was always overheating and nothing I did changed or fixed it. I focused on thermostats, sending units, and everything else. I always skipped over the water pump because it was replaced during the engine rebuild. After a year of messing with it, I finally pulled the water pump off out of sheer frustration and found the loose impeller. After replacing the pump, it runs cooler than it ever did.

 

Of course, it's always interesting to see what the solution turns out to be when members have illusive tech issues.
But I'm also interested to see if my suggested solution is the correct one.
I'm in the mood for a good chicken dinner.

 

You can just cut an old thermostat out also and use that as a washer I have encountered strange cooling problems before at least once not having a restriction in allowed the coolant to flow to freely effectively not allowing it to stay in radiator long enough to cool down getting hotter and hotter each pass ... moving too much volume can be a negitive also ...

 

I believe you have every possibility suggested here but I will throw in a couple anyway..
I never trust a new t-stat without doing the water pan on the stove with the candy thermometer
procedure and I never put in a new one if there's no problem. My '84 454 cbb truck still has the original
The other dosen't apply to you nowbut i'll throw it in for posterity as long as we're on hot engines here
A friend and competitor with a hard running Hudson Hornet 308 in a Javelin coupe, beginning of season could only run a few laps then pull out hot. It was so predictable I'd just follow and wait. They tried everything including 2 radiators w/ fans in the trunk.Nothing. At after race coffee I asked his dad/mechanic if he was running a t-stat? "yes" Is it the original ? "yes" Is it the bellows type? "yes"
And you are running a pressure capped system ? His jaw dropped, O.M.G. !!!!! It would never open up!
I almost wished I had kept my mouth shut cuz then I had to really go to work.
The other thing, on our Buick 320, I cut every other impeller off the water pump to begin with and had a huge full flow oil cooler in front of an old Ford truck4 line radiator. It ran up to 190 or maybe 205 with a face full of mud. I don't think your pump could bother at roadspeed. I did it because we geared for 5500 to 6500 rpm and since it was designed for 3700 I figured it could cavitate. It still stayed cool in parades
Good Luck Fireball 5

 

Buick Valve In Head
If the Lord meant for engines to be flat, He would have made the world that way.

 

I’ve read this thread from the beginning and like most here, I’m scratching my head... but, when you said it makes no difference in the outside temperature it still heats. I believe that is an important clue. Usually outside temperature has a drastic effect on radiator capacity, the cooler the weather the longer it takes to overheat or no overheating at all. Maybe folks are barking up the wrong tree, thinking about the radiator.
Maybe you have a crack in the engine that is reacting to temperature or something along those lines. Have you taken your car to a radiator shop and have them “ sniff” the radiator for combustion fumes? Might be worth a try.


Bones

 

What is the actual temperature it's running too hot at?

 

Have not done that. I did have the block boiled out and magnafluxed during the rebuild. But I suppose strange things do happen.

 

It will get up to around 220 and seems to stay there, but never been brave enough to get more than about 15 miles from home with it like that.

 

You may have mentioned this, but is the fan on all the time? I/e have/can you shut it off when above 45 mph?

 

Didn't even know they could "sniff" the coolant.
I do know you don't need more than your eyes to know if exhaust is entering your cooling system.

 

Its on a thermostatic control. So pretty much runs all the time. I have not tried shutting it off.

 

My go to radiator shop here in Muskogee, Oklahoma, Cincinnati Radiator Shop, had one. Sometimes the internal leaks are hard to find.



Bones

 

I still say it sounds like not enough radiator.

I've personally ran into this problem twice. Both times I chased my tail with thermostats, water pumps, etc, etc to no avail. In both cases, it turned out to be a too-small radiator. One thing you mentioned is you have a four-row radiator. I was told by a radiator guy I trust that these are rarely the answer. As the core gets thicker, thermal efficiency falls off and you reach a point of diminishing returns. Simply not enough surface area to cool properly by the time the air gets to the last row as the air is already heated.

When I get a chance, I'll dig out my 'cooling system' tester. I bought this at a yard sale years ago, and is the only one I've ever seen. I used this to diagnose the second car, and it clearly showed that the radiator was inadequate. This is a Rube Goldberg set-up that installs into the top radiator hose; getting it hooked up and not leaking with whatever adaptors are needed is a PITA. But it tests multiple items; actual operating temp via a thermometer, if any air is in the system you can see it, measures flow though the radiator, even antifreeze level. But what makes it handy is after running it to operating temp and getting all the parameters established, it has a built-in chart that tells you if the radiator is flowing and cooling enough for it's size.

 

If looking at used cars with aluminum heads this tool is a must. In this case I have my doubts leaks usally show up at low speed too. https://www.nationaltoolwarehouse.com/Combustion-Leak-Detector-P20940.aspx

 

I find a lot of overheating is caused by not enough timing at the correct time.

 

That's why I like to follow along with some of these tech/tuning threads. I usually learn or am at least reminded of stuff.
Timing!
Steven, you did say you have a Mopar Performance electronic distributor. I believe it has vac advance.
You said you checked the timing, but never specifically mentioned whether you know if the advance is working correctly.

 

Most dist don't know what engine you are going to put them on.My buddy has a 1958 caddy with a 500 eldo motor.It has a huge radiator in it but still ran hot it went to 265 in traffic . I checked the advance curve.took 1 spring off the point dist hooked up the vacuum advance to manifold vacuum it has not over heated once in traffic or cruising,I set the base timing with a vacuum gauge.

 

I've had no luck with electric fans. Both my 60 Corvette (430hp) and fenderless 40 Ford truck (8BA) overheated badly until I switched to mechanical fans with shrouds.

 

A pusher fan can actually restrict air flow at speed. When I first got my '57 Chevy Sedan Delivery, it had an electric pusher fan and a good machanical fan. It ran hot at highway speeds (215 - 230 degrees). I ditched the front pusher fan and now at highway speeds it runs at 185-195 degrees.

 

Remove the radiator cap and start up, when running look for air bubbles coming up in coolant.

 

Try putting a crossover on the heads in the rear. Hemi s are known for air to get trapped in the back. Front has a cross over, so why not the back. Simple fix by drilling and tapping and run a small cross over, say 3/8 hose.

 

Was the radiator ever flow tested? I don't recall seeing that mentioned. And probably grabbing at straws does the radiator being used have the same amount of coolant flow (GPM) as a stock Hemi radiator?

 

I’ve encountered this problem a lot. Most of the time it ends up being a clogged radiator. Easy test.....once warmed up, shut it off and feel the center of the radiator core with your hand. The center should be hot. Radiators tend to clog from the center and it progresses to the edges. It doesn’t matter if it’s new or recently rodded out......check it anyway.

 

For this money why trust you hand and if you want to use it on exhaust it hurts less https://www.walmart.com/ip/Greenpro...MIn_bpua-W3wIVgx-GCh2slwgIEAYYAyABEgJozvD_BwE

 

I can’t believe anyone reading any post here on the HAMB, doesn’t; have a temperature reading gun. They are getting real cheap. It is the most handy tool you can have! I use mine for everything! I even get the temperature of my coffee so I don’t burn myself! Seriously, I do check the air pressure in the tires on my motorhome with mine!....

When I’m traveling and stop, I will take the temp of the tires, if they are close... proper air pressure. I also check hub temp for bearing condition. Especially good on trailers.
I use mine to check for missing cylinders, start a cold engine, shoot the exhaust manifold, the cool one is the cylinder missing.
You can also use them to play with your cat! I paid $100 for mine many, many years ago and have used it so much the laser beam on mine just goes out about 4 feet now and drops off to the ground
Surely, you could get some clues with one,by getting the car up to the heating temperature and pull over and shoot different spots on the radiator to see what it’s doing or not doing.
Just my thoughts.



Bones

 

I have one but my hand has worked fine for radiators for over 40 years. Of course you have to use a little common sense when you use your hand to see if something is hot so if you are lacking in that department then a non contact tool is probably best for those kind of people.

 

Turbo, sometimes you have to drag me to embrace new technology, other times I run to it. This is one the new examples of technology that I ran to many years ago and have used on numerous occasions to diagnose hidden problems., And I have just about eliminated all burns on my hands!
It’s a win win!



Bones