My overheating senario….

[Orig69]

No

A leaking radiator cap can allow air to enter the cooling system.

 

[WileERobby]

180 stat. 16 cap. Clutch fan. Shroud. Quality radiator and proper water pump.

 

[Geoff 2]

[1] If the rad is a crossflow, they are notorious for the lower tubes blocking up with sediment.
[2] Retarded ign timing causes hot running. If the engine performance is lively, unlikely timing is retarded enough to run hot.
[3] T'stat rating. 195 opens at 195 & does not reach full open for another 20-30*. So getting to 19X on the gauge is normal. Problem is, not much safety margin left. A leaking cap will not allow pressure build up past 212* [ boiling point at sea level ] before boiling occurs. A working 16lb cap allows for a further 48* before boiling occurs.
[4] Use a 180 stat.
[5] Mostly likely cause of hot running is blocked rad, then retarded ign, then lean mixture.

 

[koosh]

Going to purchase a new rad cap…. Most are saying 16lb…. Wouldn’t it be advantageous to go with a 13lb ?
Also, wouldn’t a 160 tstat be better than the 180?

 

[koosh]

If i choose to replace radiator, i assume factory is 2 row? Is the “more rows the better”?

 

[Orig69]

You can use a 180 or the 195 which is the original thermostat.

Original rad cap is 16lbs.

2 row rad is original 3 row gets close to the fan blades.

 

[koosh]

You can use a 180 or the 195 which is the original thermostat.

Original rad cap is 16lbs.

2 row rad is original 3 row gets close to the fan blades.

So you are saying a 160 tstat and 13lb cap would not be better for a hot running motor?

 

[Ron H]

Go with the OEM spec cap. I use a 160 stat as mentioned earlier, but many prefer 180, either one.

 

[R413]

Why is a 13lb cap better than a 16lb cap for a overheating engine?

We gain approx 3 degrees of raised boiling point with every pound of pressure. So a 13 lb cap is not as good as a 16 for your hot engine.

I use 160 t stats in some cars and I would use one in your hot machine.

But really consider a different carb. I was shocked and amazed that my overheating car was fixed with a carb swap. Think about it. The entire time the engine was running it was with the wrong air/fuel mix and was building a volcano within the whole time.

Do you have a known good carb on another car, or will a friend loan you one for a few hours so you can test this out and see if it changes.

 

[BSB67]

1) get your timing correct
2) put a new 16 lb cap on.
3) 35% antifreeze, 65% distilled water
4) new thermostat.

If these don’t fix the problem, it’s probably the radiator.

 

[diesel_lv]

All things mentioned are pretty much correct. It doesn't sound like your system is running bad at all. I live where it's 125° in the summer and had to really research to make sure my 496" w a/c didn't overheat.

Fill 50/50 mix "distilled" water n antifreeze to 1" below radiator fill opening. At that point it "may" burp a little more out depending on health of cooling system. But "do not" fill higher than that.

195° stat "starts" to open "at" 195° and will regulate about 15° warmer. Recommend 180°, "not" 160° as both will have engine regulate at same temp and 160° will not be good in winter. A 180° stat "should" allow engine to regulate around 195-200°. This is normal and possibly a little lower at highway speeds.

Fan shroud, fan shroud, fan shroud.

Definitely Recommend fan clutch.

Once those things are done, you can further evaluate and see if there is still a problem.

 

[Frank Mopar]

Stant 10231 cap and any coolant recovery bottle that fits your liking. Now you have a coolant recovery system. This keeps the radiator full and keeps the nasty off the street. Everyone should be running this

 

[koosh]

Why is a 13lb cap better than a 16lb cap for a overheating engine?

We gain approx 3 degrees of raised boiling point with every pound of pressure. So a 13 lb cap is not as good as a 16 for your hot engine.

I use 160 t stats in some cars and I would use one in your hot machine.

But really consider a different carb. I was shocked and amazed that my overheating car was fixed with a carb swap. Think about it. The entire time the engine was running it was with the wrong air/fuel mix and was building a volcano within the whole time.

Do you have a known good carb on another car, or will a friend loan you one for a few hours so you can test this out and see if it changes.

I don’t have access to another carb….but if i keep this car, def will change it to Holley

 

[Ron H]

All good tips, I had a hell of a time chasing hot motor problems after rebuilding the motor adding more HP, doing several things posted up here. But, if I follow in the OP’s case, I gather nothing much was done to ‘change’ things? Maybe I missed it along the chain. Didn’t drain the radiator, tune it, no prior leaks, drove it and got overheated getting a spitting cap and mess. If so, it could be the cap, a bad/clogged stat, maybe some gunking in the rad, or an old lower hose closing up. If the water pump isn’t weeping, or there’s no fore-aft play on the fan, or pump isn't rattling, could likely rule this out as a gremlin. Also easy to inspect 'flow' through open filler after stat has opened as the cap will be off anyway burping system. I use a cut out plastic 32/oz milk bottle to stuff in the filler to reduce mess.
Before I’d go to a new rad, shroud, fan, etc. unless thinking it’s an opp to upgrade, I’d try those simple fixes including new cap, 160 or 180 stat, hose (need be), flush the system, refill, burp, and see what the result is.

 

[YY1]

Measure your recovery container capacity.

I found my stock 73 318 needed a larger one than I had initially installed.

IIRC I went from a 16 OZ to a 24 or 32 OZ, and that stopped the cycle of expanding out of the recovery tank and correspondingly lowering the radiator level incrementally each time I drove it.

I have a 160 thermostat and the car runs at 160 degrees, unless the AC is on.
Prior to increasing the recovery can size, the car would borderline overheat at about 215* when stopped in traffic, unless I manually increased RPM or shifted to N.

My car has a 26" rad, a shroud but no clutch fan.

 

[toolmanmike]

Ok guys….. here’s my issue…. Looking for a starting point to remedy.
69 Super Bee, 440, a/t ….
Take car for cruise, at least 30 minutes or more. Checking temp gage, it gets to 200 really fast, but stays there while cruising back roads around 45-50 mph.
Once stopped at traffic light, goes to 210-220. Upon resuming cruising, back down to 200 degrees. Has 195 t stat, standard no clutch 6 blade fan, no shroud.
NOW- return home park car, wait about a minute , then coolant peeing out the radiator cap, and the overflow tank!
Open for suggestions where to start!!!!

Bad cap. 180° t stat.

 

[RJRENTON]

Bad cap. 180° t stat.

The radiator cap used with a coolant recovery system is different than a regular pressure cap. Are you using the correct cap?? It has a gasket to seal the cap to the radiator neck and allows the coolant to be brought back to the radiator when the the radiator cools off. Without the proper cap, the coolant will just pee on the floor.....
BOB RENTON

 

[koosh]

The radiator cap used with a coolant recovery system is different than a regular pressure cap. Are you using the correct cap?? It gas a gasket to seal the cap to the radiator neck and allows the coolant to be brought back to the radiator when the the radiator cools off. Without the proper cap, the coolant will just pee on the floor.....
BOB RENTON

I’ll be checking that in the morning, thanks

 

[koosh]

Why is anyone shocked a car with a 195* thermostat runs 200 degrees?
That's the design spec.


How big is the recovery tank?
Does it work?

Agree on-

180 stat
shroud
clutch fan

Recovery tank is 20oz

 

[YY1]

A little on the small side.

Factory was much larger IIRC.