Runs TOOOO Hot for my Liking!

Gerald Morris

Senior Member
Joined
Mar 9, 2016
Messages
1,991
Reaction score
995
Location
Tucson
Removing the stat all together is not a good idea. It is there to keep the fluid in the radiator so it can be cooled. If it’s not there the pump will just keep circulating the hot fluid and it will just get increasingly hotter with every lap through the system.

I KNOW this Matt! I just removed it TEMPORARILY to see what would happen at maximum flow through there. BUT, since you remind me now, and it IS mid-day. I'll go ahead and drop a 180 F poppet back in. I just retarded the timing back to the spec 7.5 degrees BTC, and it seems to idle a little smoother. I know retarded timing usually = MORE heat, but I want to be sure I'm on spec, and will then work from that basis. Let's see what happens on a 75 F day, with everything on FSM 1968 spec.
 

Gerald Morris

Senior Member
Joined
Mar 9, 2016
Messages
1,991
Reaction score
995
Location
Tucson
It's the head gaskets.

Could be! No coolant in the oil or oil in the coolant VISIBLE, but you bet, this nasty thought crossed my mind. Let's see what we get today with everything now on spec, then draw conclusions.
 

Toolmanmike

Super Moderator
Staff member
Joined
Oct 25, 2019
Messages
747
Reaction score
665
Location
Iowa
I KNOW this Matt! I just removed it TEMPORARILY to see what would happen at maximum flow through there. BUT, since you remind me now, and it IS mid-day. I'll go ahead and drop a 180 F poppet back in. I just retarded the timing back to the spec 7.5 degrees BTC, and it seems to idle a little smoother. I know retarded timing usually = MORE heat, but I want to be sure I'm on spec, and will then work from that basis. Let's see what happens on a 75 F day, with everything on FSM 1968 spec.
Put the thermostat in a pan of water on the stove with a thermometer in the 150-212 range and watch the thermostat open. You may have to go through 2 or 3 to get one that works correctly.
 

Gerald Morris

Senior Member
Joined
Mar 9, 2016
Messages
1,991
Reaction score
995
Location
Tucson
All I can add is that you appear to have a B engine and in Los Angeles temperatures in the summer, no 22" Chrysler radiator will adequately cool that engine in Los Angeles , much less in Tucson temperatures in the summer that are usually significantly higher than Los Angeles temperatures. Those 22" radiators aren't adequate for Los Angeles even with everything working properly and a clean system especially in slow moving traffic.

I personally have never had a 160F thermostat make any difference in temperatures in the 90F and above temperature range nor do I see why they should unless one is driving at freeway speeds with everything else working well. In traffic where these under-designed 22" radiator systems are weakest, such a thermostat shouldn't make any difference when equilibrium is achieved.

IDK about this being a B transplant, but the rest of your observation jibes very well with my own experience. That radiator IS rated (in theory) for C body 383 cars, but I DON'T TRUST 2 ROWS OF ITTY BITTY COPPER TUBES TO COOL MY WEEDWHACKER HERE, let alone a 383!

Now, my 1965 2524984 cooled Mathilda's 2 barrel. AC encumbered (yes, she had that when we bought her, though I pulled it off immediately.) 383 JUST DANDY for the first 2 summers I drove her. The FIRST summer, 2016, I even left the straight 17 inch (I think) 6 blade steel fan in place! The second summer, I upgraded to a clutch driven 20 inch 7 blade fan, which cooled her again VERY WELL, BUT, ALAS! that old radiator sprung about 3 too many leaks for further summer duty, though I wouldn't replace it until May, 2018, with a Cold Case MOP753a. Now THAT radiator REALLY SHOULD be advertised as for A or B body cars, being a mere 22 x 16 inches, but it IS 3 inches thick, with 2 rows of 1.25 inch tubes, and it actually held about a quart MORE coolant than the old Mopar 2524984. That served us well until I STUPIDLY BONDED IT WRONG, GUARANTEEING THE VERY DISASTER I WAS ATTEMPTING TO AVOID!!!! GRRR!

I copped a Speed Cooling 22 x 18 inch radiator this past spring. It was cheap, and worth what I paid, but I can't really recommend them. It worked, but only because the rest of Mathilda's cooling system had been built up to assure that a mediocre at best radiator COULD work.

Yes, by 1968, Mopar committed to 26 inch radiators for serious engine cooling. The expensive 22 inch Hi Alt sorts were history, for B/RB cars.
 

Gerald Morris

Senior Member
Joined
Mar 9, 2016
Messages
1,991
Reaction score
995
Location
Tucson
Put the thermostat in a pan of water on the stove with a thermometer in the 150-212 range and watch the thermostat open. You may have to go through 2 or 3 to get one that works correctly.

Yep! Exactly what I thought of last night. Hell, I'll go boil up a big pan right now. I can pick from quite a few here actually. Hording is GOOD, if you know WHAT to horde....

20 min later....

DID IT! ALL 3 OPENED SIMULTANEOUSLY, like clams in good water....
3-BRONZE-CLAMS.jpg
 
Last edited:

Gerald Morris

Senior Member
Joined
Mar 9, 2016
Messages
1,991
Reaction score
995
Location
Tucson
Afternoon Report:

Took Trudi for a run to DIYdiot DeepOh. 2.8 miles of heavy stop & go traffic. Retarding the timing back to spec got rid of WOT backfiring, though the motor still stutters from fuel starvation when attempting WOT acceleration. Having already swapped out the UTTERLY FILTHY, WORTHLESS GAS TANK for my CLEAN SHINY one from Tilly, the sole remaining source of dirt is the fuel line. Will replace another fuel filter, check it for debris, and inspect the line from tank to pump. The engine now idles very smoothly indeed, but FUEL STARVATION CAN CAUSE OVERHEATING! Must eliminate this possibility, utterly. Can use some JEGs line I have if I MUST.....

Coolant temperature still rises in steps equilibrium. 1st Step, ~210 F. This remains until upset by too much idling in traffic. When cruising, temperature actually will FALL as low as 205F at this first quantum. Wind clearly helps cool the system. Encouraging!

2nd Step, 230F. Idling in traffic eventually drives temperature up to 230F, where it then will stay, especially with some motion to help cool the system again. Once the system reaches 230F, temperature will not go below this by more than 1-2 degrees, unless possibly some sustained drive can occur. Even when stopped, spinning up the fan and water pump WILL cool the system several degrees. This helps prevent severe overheating, long enough to get home anyway.

3rd Step, 240F., Engine and coolant reach this temperature when approaching home on barrio streets and trailer park driveway. GOOD NEWS! The engine does NOT go over 240F when making the parking approach. At no time this afternoon did the "Hot" light come on. I still don't know IF or WHAT Chrysler specified as the proper temperature FOR the idiot light to come on, but ote that even close to 250F it doesn't appear. It DID appear briefly when the new gauge showed something around 255F. I DON'T WANT THIS ENGINE GETTING NEAR THAT TEMPERATURE, EVER!

Surmise: The engine isn't getting adequate coolant flow, from air or internal coolant. When in motion, the engine temperature temporarily stabilizes at some quantum reached as the car begins to move at 3rd gear driving speeds. When stopped in traffic, the engine coolant then resumes heating, until interrupted by vigorous air flow, coolant flow through the system, or both. Temperatures DO decline given adequate cooling fluids though! There is good cause to think this system can be cooled with upgraded cooling components.

Possible Problems: 1.) Fuel starvation: Fuel flow MUST be made RELIABLE and ADEQUATE. If, after one final filter replacement, the engine still stutters under WOT acceleration, then fuel line cleaning or replacement will have to be implemented. 2.) Cylinder block water jacket: Noting that on both sides, the cylinder block sides show significantly lower temperature (~195-200F) while the thermostat housing and water pump radiate at ~230F, with the cylinder heads showing ~ 215-220F, the possibility that extensive debris yet persists in the lower water jacket must be addressed. The wall plugs, one on each side, can be removed, and a fish wire can be inserted to ascertain whether significant debris remains in the lower jacket. If so, combined compressed air, pressurized water and vacuum cleaning all can and should be used to remove internal debris. Note: The engine was initially flushed with a water hose under normal house pressure attached to the heater intake hose after running the engine with an organic acid solution in the water jacket meant expressly for cleansing the cooling system. The engine ran throughout this procedure, forcing water through the cooling system from the pump intake, and out the top of the radiator via a plug-in spigot designed to direct coolant flow away from the running engine. This method has been used annually, and sometimes twice annually on my earlier MoPar B/RB vehicles. When the outflow tastes potable, the procedure is finished.
3.) Cylinder head gaskets: Given that this engine and car sat without running or care for several decades prior to an abortive attempt at restoration by the party that sold the car to me, it is entirely possible that the head gaskets have deteriorated to uselessness. Such HAS NOT YET BECOME APPARENT based on the engines clean combustion, and complete LACK of tell-tale residues of coolant in the crankcase oil, or crankcase oil in the coolant. No water vapor can be seen or even felt in the exhaust. No oil smoke can be detected. The emissions test, in fact, at 196 ppm for hydrocarbons, was REMARKABLY CLEAN. OIL PRESSURE remains respectably high, around 45 psi at any engine speed over 600 rpm. A compression check will be performed when time for such avails. At present, cylinder head gasket failure is deemed extremely unlikely.
 

Gerald Morris

Senior Member
Joined
Mar 9, 2016
Messages
1,991
Reaction score
995
Location
Tucson
I've had 4 68's. I only drove two of them. Two were bought in Texas (440 & 383) and two in PA (440 & 383). All 4 of them had a shroud on the radiator. I never have had over heating issues.

Were all 4 radiators 26 inches, or were some 22 inch? I have an old 1965 Imperial shroud which should fit this 22 inch radiator with little trouble. Yes, I'm NOW leaning toward increasing airflow as The Solution to this problem. I even have a monster 19.5 inch 7 blade clutch fan, probably from a truck, which I CAN bolt up, though I couldn't shroud that big beast the last time I used it. I replaced that with an 18 inch 6 blade De Rale fan, which I eventually DID shroud, by my own work, but it WORKED!
 

live4theking

Old Man with a Hat
Joined
Nov 24, 2014
Messages
11,961
Reaction score
7,969
Location
Rockland; Venango County Pennsylvania
Were all 4 radiators 26 inches, or were some 22 inch? I have an old 1965 Imperial shroud which should fit this 22 inch radiator with little trouble. Yes, I'm NOW leaning toward increasing airflow as The Solution to this problem. I even have a monster 19.5 inch 7 blade clutch fan, probably from a truck, which I CAN bolt up, though I couldn't shroud that big beast the last time I used it. I replaced that with an 18 inch 6 blade De Rale fan, which I eventually DID shroud, by my own work, but it WORKED!
The two 440's yes, they were both AC cars. The one 383 car was also an AC car so I would think that it did also. The other I don't recall. I gave the radiator to a friend I think, but that's been close to 20 years ago.
 

'66 Fury I

Member
Joined
Aug 19, 2019
Messages
180
Reaction score
229
Location
Moncton, NB, Canada
I have had good success with adding an extra row of tubes in the rad core. This adds cooling surface and allows more time for the coolant to cool. If flow remains constant through the engine, then the extra row of tubes allows the flow in the tubes to slow. More time in the tubes= more temp drop. Just a thought. Lindsay
 

saforwardlook

Old Man with a Hat
FCBO Gold Member
Joined
Oct 8, 2011
Messages
7,098
Reaction score
11,917
Location
California
If you want good cooling primarily in traffic, low speed conditions you must focus on radiator width.

If you need more cooling at highway speeds, you need to focus on radiator depth or more rows of tubes.

GM went to crossflow reasons for a very good reason many years before other manufacturers such as Chrysler. They also had much better air conditioning systems. That is a big reason why they outsold every other manufacturer in the U.S. in the 70s..........................addressing customer issues relative to comfort and interior quality and vehicle driveability long before the others.
 

Gerald Morris

Senior Member
Joined
Mar 9, 2016
Messages
1,991
Reaction score
995
Location
Tucson
Ummmm I thought (and read) that the flapper type thermostat was a no no for the big blocks, especially the 440 and the poppet valve was the only one to use.

View attachment 491142

View attachment 491144

.

THAT's GOOD TO KNOW! I had a RobertShaw clone with a Mr. Gasket, and YES, I too have seen what's depicted in the FSM. My Mr. Gasket had stuck to the housing a little with the RTV, and I saw it give and warp a little when removing it, so I unpacked the Carol poppets. The FSM quote given above does NOT specify that flappers WON'T work, nor had I EVER seen any specific interdiction on using flapper type thermostats in either my 66 or 68 FSMs. Still I'll go ahead and order up another good RobertShaw clone, all the same, to be safe. THOSE ARE what Ma Par shows as their preference, at least in 1968 and earlier nomenclature. Now, have you any specific source expressly warning against flapper type thermostats, or are you assuming an interdiction based on this FSM quote alone?

THANK YOU for that datum!
 

Gerald Morris

Senior Member
Joined
Mar 9, 2016
Messages
1,991
Reaction score
995
Location
Tucson
If you want good cooling primarily in traffic, low speed conditions you must focus on radiator width.

If you need more cooling at highway speeds, you need to focus on radiator depth or more rows of tubes.

GM went to crossflow reasons for a very good reason many years before other manufacturers such as Chrysler. They also had much better air conditioning systems. That is a big reason why they outsold every other manufacturer in the U.S. in the 70s..........................addressing customer issues relative to comfort and interior quality and vehicle driveability long before the others.

I DIDN'T KNOW ABOUT GM INNOVATING CROSSFLOW radiators in the 1970s. Their ACs DID WORK though! Growing up in Fukt Worthless Tx gave me ample opportunity to test automotive AC. I NEVER OWNED ONE THAT WORKED, FROM 1978 TO NOW, I've NEVER driven or owned anything with a working AC. I want to get one working for my children now though.

Looks like I'll want both width and depth. The latter distinguished my cherished 2524984. DAMN! how I WISH I could resurrect the old radiator ARTIST I met in the 1990s who fashioned a heater core for my 1960 Ranchero out of a scrap radiator! That guy was GIFTED, and Big John built a business based on his talents with a torch and solder, brazing rods et cetera. Now he's gone to the Great Junkyard Yonder, RIP.

I ALSO need to mind a BUDGET when radiator shopping! I have a 22" yoke, and would prefer to stay within that limit, so something with good area and volume is the ticket. Unfortunately, Cold Case made something really meant for A and B bodies, just 16" tall, and they WON'T change that to 18" for me without my sending them my *4984. Not happening....
 

70bigblockdodge

Old Man with a Hat
Joined
Jan 19, 2013
Messages
13,061
Reaction score
10,402
Location
Avonmore Pa.
Your carburetor is lean. It is contributing to your overheating. A/C water pump is supposed to decrease water flow.
1. The crank pulley on A/C cars is always very large diameter and WP pulley is usually smaller than no A/C this makes the pump and fan spin faster.
2. So the pump is actually lower volume to circulate water slower allowing it time to cool off in larger radiator that is sitting behind the condenser and it's added heat.
3. I call BS on this because they all look the same and usually have same vane count. Result of being a engine that is out of production for 40+ years.( I know the anti-cavitation plate pumps look different, save your breath. Gerry isn't using one of these high rpm pumps)
Back to lean condition. Check plugs and try running it with choke partially closed and see if it improves. Both are free checks and free is good.
If the system pressurizes within a minute from dead cold/morning you may be looking at a head gasket.
Still leaning toward lean condition. Are we 100% sure vacuum advance is working properly? As in rate, amount and diaphragm that does not leak.

Also a 30 gallon grease barrel in plastic or metal is a nice diameter for fan shroud. Adjust the depth/length by cutting it lower down the body. Attach it to a flat piece of sheet metal with a number of tabs left in place when cutting the hole in center out. Make them long enough to get past the top ring/lip of the barrel and screw or rivet them to attach. Fold over a 1/8"-1/4" @ 45-90° on the top and bottom to give it some strength and screw it on to shroud tabs on the radiator sides
 
Last edited:
Top