Radiator Question for the Guru's

-
gunbunny

gunbunny

Well-Known Member
Joined
Apr 14, 2009
Messages
3,884
Reaction score
2,840
Location
Cincinnati, OH
74 Duster /6 w/19" radiator.
less than 5K on rebuild 4 years ago.
Having an over heating issue at highway speeds.
If I'm not pushing the car, no issues.
So, with that info, I'm fairly certain that I have a water flow issue and not air flow.
Going into it with that thought process, I decide maybe I should flush system. Perhaps the clean up prior to the rebuild knocked something loose.
I took the cap off and while full I can see some crud is collecting badly in the radiator core. I have some stout cleaner and decided to add that and let it circulate. But when I open the drain ****, nothing comes out.
Now I'm concerned. I'm positive that I have a restriction, which explains the issue.
I drained some coolant and placed a quart of the flush and a 1/2 quart of white vinegar into the radiator.
Not convinced this is going to clear up the corrosion.
So, my question is, if I'm unable to find a new 19" radiator, will a 22" bolt into its place?
I'm not interested in a 3 core or anything fancy, just want to properly cool the engine.
 
A Rad shop should be able to remove the tanks and clean out the core and/or recore it.

OR

pull the rad out and flush with hose right side up from top and upside down from bottom. you can also get a good look at the tubes from the hose inlets and outlets.
 
Dana67Dart said:
A Rad shop should be able to remove the tanks and clean out the core and/or recore it.
Click to expand...
That is an option. And I may have to go that route, but I was wanting to take this car to Mopar Nats.
I have a 22" from an Aspen available if I want it. Just don't want the person offering to go thru the trouble if it won't fit.
 
With the engine idling, and on the cold-air side, measure the temperature difference between the water leaving and the water entering, the rad. With an IR gun you should see a difference of ~30*F.
Now rev it up to 2000, wait about a minute or two and retest. While waiting observe the lower rad hose for getting sucked flat, and make sure the fanbelt is not slipping. Also take your IR gun and walk it from side to side across the rad at multiple heights; looking for hotter spots/areas, which would indicate plugged tubes.
 
If the bolt holes don't match up with the bigger rad. you can drill new ones to make the bigger rad fit. I had a 318 with a 22" rad and put in a 26", but I had to drill 4 new holes but the bigger rad. gave me peace of mind.
 
Take the thermostat out, put a piece of cardboard in front of the radiator to get it hot, then stick a water hose in the top hose and pull the bottom hose let that baby flush.
 
If you got crud visible in the radiator, your going to want to pull the radiator and flush with a water hose as mentioned, and also take the heater hoses loose and flush heater core out too. Pull the drain plugs in the side of the block, flush through heater hose connections while blocking the opposing connection. The 22 inch radiator support opening went to a 26 inch opening in 1973 and carried through all other models, the pull-a-part site I just referenced showed that all radiators from Aspen, Volare, and everything else from 1973-1982 cars interchange.
 
AJ/FormS said:
With the engine idling, and on the cold-air side, measure the temperature difference between the water leaving and the water entering, the rad. With an IR gun you should see a difference of ~30*F.
Now rev it up to 2000, wait about a minute or two and retest. While waiting observe the lower rad hose for getting sucked flat, and make sure the fanbelt is not slipping. Also take your IR gun and walk it from side to side across the rad at multiple heights; looking for hotter spots/areas, which would indicate plugged tubes.
Click to expand...
Fan belt is tight, not slipping.
There are "cold" spots on the radiator. Mostly in the lt lower qtr of the radiator.
Upper rt reads 177° and lower lt is at 141°. with several other cooler pockets scattered.
The flush that I added has Sodium Citrate Dihydrate and I also placed White Vinegar into the radiator as well. I'll let it soak for a day or so then flush. If not, then I'll pull it and take it to a radiator shop.
 
The old caustic soda flush worked pretty well on the corrosion, but it worked on the water pump bearing seals, too. The citric acid flushes are lot less aggressive but I would still flush everything with a hose first after draining before running the engine. But it really sounds like your radiator needs to be rodded out. I am weary of junkyard or used radiators, most of the older ones I have dealt with had so much hidden salt damage they fall apart within a month of usage.
 
get a new aluminum radiator, big as will fit. flush your engine block. replace your thermostat.
 
Pull it.
Pop thermostat out and backflush engine.
I suspect it was run with straight water at some point.

Lay rad flat and fill it with rad flush and hot water then let it sit for a few hours.
A good rinse and re install.
Big issue is the debris piled up in the block,it is difficult to remove.
 
I think it might fit - sorry that is best I can do to really try to answer the specific question that you asked (can a 22" replace a 19") . I guess nobody else knows either...
 
Tooljunkie said:
Big issue is the debris piled up in the block,it is difficult to remove.
Click to expand...
a 26" should fit between the frame rails, but if you leave a bunch of crap in the block, it'll get clogged too. sometimes it's worth pulling the motor, remove all the freeze plugs, and run some stiff engine brushes through it while hosing it out
 
In the early days of my making believe I was an auto mechanic, nobody ever stressed the using of distilled water with antifreeze in the rad..
I know my Father use to take the garden hose and mix it with the antifreeze. Whenever I bought a used car I would look in the rad and see the white scale build up in there, which meant having it boiled out or replace it. For the last 40 years I've been using distilled water and never see that scale build up in any of my cars.
 
Okay, more info.
I replaced the heater core a year ago.
I rebuilt the engine 2016. At the time, I removed all freeze out plugs and power flushed the block.
What I didn't do at the time was replace the radiator, mea culpa.
So, I can have the current radiator rodded, and I'm sure it will be just fine, but I'm thinking I'd like to put the larger radiator in it's place.
If it will direct bolt, I'm a player.
I had a stroke a couple years ago and the left hand doesn't cooperate very well, so doing much in the way of drilling or modification isn't to appealing to me.
 
gunbunny said:
74 Duster /6 w/19" radiator.
less than 5K on rebuild 4 years ago.
Having an over heating issue at highway speeds.
If I'm not pushing the car, no issues.
So, with that info, I'm fairly certain that I have a water flow issue and not air flow.
Going into it with that thought process, I decide maybe I should flush system. Perhaps the clean up prior to the rebuild knocked something loose.
I took the cap off and while full I can see some crud is collecting badly in the radiator core. I have some stout cleaner and decided to add that and let it circulate. But when I open the drain ****, nothing comes out.
Now I'm concerned. I'm positive that I have a restriction, which explains the issue.
I drained some coolant and placed a quart of the flush and a 1/2 quart of white vinegar into the radiator.
Not convinced this is going to clear up the corrosion.
So, my question is, if I'm unable to find a new 19" radiator, will a 22" bolt into its place?
I'm not interested in a 3 core or anything fancy, just want to properly cool the engine.
Click to expand...
When you say "overheating" how hot is it getting? Is it pushing coolant out?
 
toolmanmike said:
When you say "overheating" how hot is it getting? Is it pushing coolant out?
Click to expand...
Nope. Not letting it get to that point.
But the gauge is all the way to 250* and the laser says it’s 235*. The coolant is nice and clean. But nothing comes from the petock. I can only drain by removing the lower hose.
No issues when I drive on back roads only at highway speeds.
Makes driving it to Mopar Nats a no-go.
 
Last edited:
I remember parting out a /6 68 Barracuda about 1980. It had a small radiator (19"?) with a metal panel on the side to fill in the wider opening. Bigger rad was used with V-8 cars that needed a larger radiator.

My point is, your 74 will probably take the 22" radiator no problem. Why don't you borrow it, get it home, take some measurements and see if it will fit? Also check hose inlet and outlet location.

In the mean time, take your 19" to a rad shop and have them test it and give you an estimate. Those things were run for years in LOTS of /6 cars without issue. I know mine works fine.

It's about 10 days til the Nats. Lots of time to get this done in time.
 
Last edited:
Well,
I can confidently say that a 22" radiator will fit in the space of a 19".
It's in, and it looks pretty too.
I flushed the system for about 2 hours last night.
A first the coolant looked great, but then it turned a nasty brown. I guess I got clot out.
I pulled the overflow tank and saw that there was about a 1/4" of sludge in the bottom of that.
I pulled the petock out of the bottom of the radiator and it is packed with sludge.
Unfortunately I had a stroke a couple years back. I lost a lot of muscle memory in my left hand. I kinda forgot that I lost that ability to know when something is just tight enough.

IMG_2231.JPG


So I guess tomorrow, I'll get a piece of rubber line and make a splice. That'll hold until I can get it under a lift.
Can't win em all I guess.
Hopefully my overheating issue will be resolved.
 
Well, it's in, it's done and I'm damn happy I did it.
My overheating issues have vanished.
I drove the dog out of it tonight on the highway and temp gauge never even got to the half mark.
I strongly suggest the 22" upgrade. The radiator went right in and there was no modification needed. Also, if you decide to add a shroud, those are available as well.
This was mostly painless and for the $50 extra over sending the old 19" out, well worth it.
 
You must log in or register to reply here.
-

Back
Top