Duster 318 overheating

[69bronzeT5]

My Duster keeps overheating for some reason. The thermostat is brand new, all the water jackets and everything have just been cleaned completley out and the radiator is in good shape. The timing and everything is all good......any ideas? I really need to get a shroud, that will help things.

[Back N Black]

Cody, there is a high failure rate in new thermostats, was it cooling ok with the old one? what i do with a new thermostat before i install is put it in a pot of boiling water with a thermometer and make sure it opens at the right temp.

[71ChallengeHer]

Cody, Make sure there is not a piece of permatex stuck in the thermostat.

[Drop Top]

When is it overheating? All them time or at a stop light? I have a 72 Dart as a daily driver. Had a problem at stop lights. Put  bigger radiator, shroud and a clutch fan on it and solved the problem. That was after I cleaned out the block and checked the thermostat. How many miles on the car? If the car has over 100,000 on the odometer then it just might be woreout. I just rebuilt a 360 and the trans. Now I have a problem getting the car to get to operating temp and it gets over 100 here. Now I feel comfortable to install air.

[69bronzeT5]

Well, we took the thermostat out to see if that was the cause and it's still overheating. It dosen't like spew and steam but a couple trips around the block and when we park the car and shut it off, coolant comes out of the overflow for about 40-45 seconds...

[b5blue]

It may be "burping" out an air pocket and adjusting it's coolant level.

[CDN72SE]

I had a similar problem and it was the radiator cap, the seal was worn. I replaced that and it solved the problem.

[BigBlackDodge]

Is your overflow tank full at start up?


BBD

[69bronzeT5]

Is your overflow tank full at start up?


BBD

I don't have an overflow tank....

[BigBlackDodge]

Is your overflow tank full at start up?


BBD

I don't have an overflow tank....

Thats why your coolant dumps out then.....it has no place to go after engine shut down and heat builds up in the motor expanding the coolant volumn.


BBD

[NHCharger]

Neither one of my Chargers has an overflow tank. On my 72 if I fill the radiator to the top it will burp out the excess coolant once it gets hot. The normal level is about 1 1/2" from the top of the tank, this allows for expansion of the fluids when they get hot.
Once it cools down and you look in your radiator and if you can't see any coolant then you do have a problem.

[68r/t]

You may have a blown head gasket, check to see if there is air bubbles in the radiator when the motor is running.

[doctor4766]

Is your overflow tank full at start up?
BBD

While on the subject of overflow tanks..
I have a 26" radiator that currently doesn't have an overflow tank.
If I were to connect one up will it work ok with the 26" and is there a need for a special cap?
I'm sure I read somewhere that a different cap is needed.

Mine drops to around an inch and a half too so it would be good to be able to recover what spurts out.

[69bronzeT5]

You may have a blown head gasket, check to see if there is air bubbles in the radiator when the motor is running.

The motor was just gone through last month....it's only been running in the car for 3 days now

[TUFCAT]

Listen to these guys - they're right!

I agree with everything said...especially about overflow tanks and radiator caps. Both are often overlooked. Most people are often misinformed on how a coolant system works and end up installing new radiators that really don't "fix" the problem.

First thing, don't overlook the radiator or the block . Both could be full of sediment or debris which can restrict flow nearly 50-75% easily...and constrict proper flow rate. Clogged engine passages act as insulation that really trap heat in the motor (more than a clogged radiator because there's no air passing through).

Since you said these are okay....here's the next step.

Flush the entire system to remove old coolant and potential contaminants.

Consider installing an overflow tank. Before you condemn this, (I wouldn't put one on a car that wasn't kosher for the year and model) but I think 1974 Dusters were required to have them due to the feds not wanted any potentially toxic pollutant chemicals dripping out of cars. If you can find one from a 1974, if that was the first year, then definitely put one one...

Now the next problem - radiator cap. This is another big, and often overlooked problem. A leaky cap can also be a culprit of allowing air back into the system as the radiator cools. The volume of air can eventually replace the volume of missing coolant that your radiator just dumped on the ground...thus the need for an overflow tank. Also as your radiator cools, the fluid contracts and pulls in more fluid from the bottle - going straight back into the radiator. This eliminates air bubbles.

[TUFCAT]

Cody, think of any tiny pockets of air in your system as places where the coolant isn't touching metal, therefore not transferring heat.  It could also prevent proper flow of the coolant thoughout the system.

In most cases, if the coolant gets to much air mixed in, this "bubbly mixture" can't carry enough heat out from an engine and into the radiator to shed it off.

Also, by a product called "Water Wetter". It prevents water bubbles from forming when coolant reaches its boiling point, preventing bubbles in the system. I've used it for some years now with great success.

[mikesbbody]

And, like you said Cody definitly add that Shroud