Do I understand that you are making decisions based on the stock gauge with an unknown source sender? May I suggest that you not do anything until you actually know what temps you are working with?

As to the belching of coolant when shut off, big blocks (and Hemis) have always heat soaked. Either put an overflow bottle on it or leave the coolant down an inch or so in the radiator. In my humble opinion, that is not indicative of anything other than it's a big block Mopar.

At any rate, if you want to throw $10 or so at the Water Wetter, go ahead. But that in not gonna fix any real problems.

Get an accurate temp gauge and sender to determine if you actually have a problem and when. Then, remember this good rule of thumb; over temp at hiway speed is typically a water flow problem while over temp at slow road speed is typically an air flow problem. It is also a good idea to look at the water pump housing bypass hole and size it down if excessive. It allows hot engine water right back into the incoming cool water.

Yes ,,,,,,,,,,,,,,,,,,and NO

its based partly on 25 plus years as a service tech. The car was warmer than normal 180- 200 degree range, Im sure of that. At normal temps I can hold the upper rad hose , last nite I couldnt for more than a few seconds at most . At normal temps the system does not gurgle/ feel likes its boiling inside the hose
So Actual live temps I dont know. Just yet. I will pick up a laser temp gun on monday to ck temps at various locations underhood

The car has sat for the most part the past 15 plus year or more. Its had less than 1000 miles put on it since completed in 2004 . So I will drain/flush coolant , ck / replace the thermostat and refill with with distilled water with maybe a little bit of coolant for WP lubricity if nothing else
the temp sender was nos mopar when installed, the gauge is the original I believe. The radiator was re-cored with a new 3 row core at the same time. So I have serious doubts its a problem, BUT I plan to ck it anyway

You might find that higher stall converter is putting more heat into the system if you are using the in the radiator cooler.

Generally speaking, cooling issues at low road speeds are airflow related. At higher road speeds it's usually water flow related.

But more heat into the system menas you have to be able to remove it as well. If you don;t have an aux trans cooler you might think about that.

The car does have the hemi aux trans cooler on it .

Anti Freeze is what it's called. It prevents freezing and also has anti rust and lubricant in it.

You'll find lots of car guys were you live now just run distilled water and an additive or even old water pump lubricant. It's not because they are too cheap to by Anti Freeze. Water cools better than Anti-Freeze.





Here in So Cal, I run Justice Brothers Super Radiator Cooler and Reverse Osmosis (RO) water in my Barracuda for the last 9 years. I also put in Justice Brothers Cooling System Protectant for added anti rust and electrolysis protection.


Very complete test of coolant additives:
http://www.turbomagazine.com/features/0703_turp_cooling_system_additives/viewall.html

"Justice Brothers' Radiator Cooler gave us the lowest temperature during our testing - 177 F - and provided the lowest average temperatures overall when mixed with water alone."




A good radiator additive does a lot more than just acting as a wetting agent. It should also provide anti-corrosion, anti-cavitation, electrolysis resistance, anti acid, lubrication, SCA's (Supplemental Coolant Additives), added thermal conduction... They should remove heat better than antifreeze. Boiling in a pressurized system of water alone is 257 degrees.

The object is to remove heat before going into a boiling situation.



Here's pictures of the inside of my Radiator from 2016, 5 years after it was installed. Just before a drain and fill.

Same here on my 340 Dart.

Thanks all,
But an aluminum radiator is 100% out of the question on this car .

I have some ideas and things to try , weather permitting will get something done tomorrow

Report back what you find.

Being the car it is, they're typically not driven 2-3 times a week. And if came from the snow belt, it was parked all winter.

Could have sediment and gunk in it. Might want to try and good old fashioned power flush. If you already haven't.

Gurgling, huh ?
Take a look at the seal on your radiator cap.
Grab a new radiator cap, swap & test.

Right now, I think thats my starting plan of attack . Open it up, drain and flush the system completely , including pulling the drains in the side of the block, ck t-stat operation / might go ahead and install a new one , then refill with mostly water.. I ckd earlier and I think the fan diameter could be a little bigger . As it has approx 1.5" clearance between the fan blades on each side and the edge of the shroud. So if my changes do nothing I make look for a larger diam fixed blade fan as a next step ( my current fan is a 7 blade fixed fan btw )

EDIT, just measured------. fan shroud opening is a click over 20" , fan blade is a click over 17" . measuring side to side

Installing a coolant overflow bottle is a good idea,

A tighter fit between fan tip and shroud will nearly always improve low speed cooling,
but under hard acceleration the engine’s torque will cause a twist off centerline.
You might white paint just the tip of the longest fan blade
and then attach two pieces of something soft like weatherstrip on the left and right sides of the shroud
and watch for “witness marks” of white paint on these weatherstrips to tell you the maximum fan diameter.

Mercedes OEM radiator caps are usually higher psi ratings.

Could the car’s heater core be quite old and unable to withstand more than 16 psi?

Im reasonably sure the heater core is original, raising pressure is IMO a gamble, One Im not sure Im willing to take . At least not until all else has been exhausted

But, yes some kind of overflow bottle is most definitely in its future . Did some online reviews last nite and it seems this stuff called purple ice is a better option


here is where I think I will try 1st.

Drain and flush the entire system, refill with distilled water .Will ck thermostat operation and temp rating ( potentially replace it it nothing else but to change temp ,,,1st up switch to maybe a 180 ) and add a bottle of this Ice stuff .

Ck for cold spots in the rad with a temp gun at same time . Then see if or where i need to go from there .

Anyone know if a slightly larger diam fan blade is avail for a non fan clutch mounting ?


EDIT,
From reading reviews the overwhelming comment Ive found so far for ANY of these wetter additives is they seem to have a very minimal effect if any to a mixture with coolant. But seem to help anywhere from 5 to sometimes 20 degrees drop if using straight distilled water

I always try the simple things.

1) Fan belt tight?
2) Air side of the radiator clean?
3) Lower radiator hose firm?
4) Thermostat functional?

Then you can get to the more drastic measures like pulling the radiator and internally cleaning it. Face it, if this is a stock engine, Chrysler built thousands of them without heating problems.

I use water wetter in my race car but as much for the corrosion protection as anything else.

Agreed,
My primary question was if the water wetter additive even worth the effort at all. And from my digging around , its worth a try. Provided I use water only. Im in Southern AZ so freezing temps will never be an issue
I plan to pull the Tstat later today and see what it has installed . then decide to stove top hot water ck it or just replace it . I have a temp gun and once its flushed and refilled will ck for cool spots in the radiator

Like I said, the car never overheated persay. Just a tad warmer than I would prefer it be . I will ck engine temps with the gun to see at what temps the gauge is operating at in various postions. And will ck ignition timing while I have the hood up.
I do plan to ck and see about putting a spring in the lower hose while its drained / opened up if I can find one today.

I talked to the previous owner last nite and he couldn't remember if its standard bore or not. I do know it had 12.5 -1 pistons but they were cut down and he feels its probably still in the 11- 11.5 range . THAT might something I have to deal with at a later date . Primarily because pump gas friendly it is not

I've had a couple of thermostats lately that passed the hot water test but failed to work properly in the car. Both times I had to scratch my head for a while to figure it out. My Duster ran cool but took a long time to heat up. The thermostat worked properly when dunked in hot water but when I ran the engine with the radiator cap off I could see water flowing even when the engine was dead cold. I had kind of the opposite issue on another car where it was hot but thermostat checked out. Evidently in practice it just wasn't opening nearly enough for some reason. One thing I discovered is that there are a lot of super cheap Chinese garbage thermostats on the market these days. Evidently the Chinese can't read blueprints and don't understand QC. My advice is buy high quality and then double check operation in the car.

195 degree OEM 1995 Magnum 5.9 V8 thermostat failed after 5 years in 50/50 Ethylene Glycol mix coolant when the brass arm cracked which cocked the valve partially open.

180 degree “Balanced Flow” Robertshaw thermostat failed in the closed position about a year after I began using Evans NPG coolant.

205 degree Stant “Standard Grade” thermostat failed in the closed position after 9 years in NPG coolant.

I would think thermostat design would have advanced to where they last 20+ years when coolant is changed on schedule.

Evans NPG coolant is supposed to be “Totally Non-corrosive” to iron, aluminum or brass compared to water, EG or PG coolants.
But I have wondered whether it could chemically react with the wax in the thermostat.

Thermostats in general have been going to $hit the last few years. Most are a real crap shoot as to whether they will last past getting wet the first time. I had used the Mr Gasket high flow thermostats for years, they clearly flowed more. But the last few I have installed have been junk.

I now use the Stant Superstats. The opening is on the small size in my opinion so I add some holes to them to help with flow, but I haven't had any real problems with them............so far.

I too use Stant Superstats and drill four 1/8 holes to aid in flow.

If it were mine and the tubes in the radiator showed any gunk I'd take it to a good shop and have it rodded out.

When I was having overheating issues years ago with my Dart I tried water wetter and purple ice. They made zero difference. It was running a new replacement 24" radiator, 160° thermostat, black magic electric fan and a belt driven water pump. I replaced the copper with a 24" cross flow aluminum radiator and had to buy another fan because there wasn't enough room for the one I had, it still ran hot so I put a new Flow Kooler water pump on, no help. I was about to pull the motor when someone here suggest that I try a MP viscous fan. A friend of mine had a nearly new kit so I bought it, then cut and sectioned a 26" shroud to fit the 22" aluminum radiator. All my over heating issues went away, I'm satisfied that if I had done this in the beginning there would've never been issues. I still run this set up on my 434" small block and on the hottest days I've never seen it over 185°, even at the drag strip.

I'm completely in agreement with Mike! I used the Zerex G-05 with WW in my 68 R/T that was a hot runner from the day I started it. I can recall one of the previous owneres talking about how hot it ran. It definitely had positive results. easy first step Bill!
Good Luck!!