I have a 225 that was just rebuilt from bumper to bumper. New radiator and cap, new thermostat new head gaskets,,the works..Why don't the cooling system pump up? I have no leaks!!,,what the hell..does anyone know what else I can look for that can cause this. Not sure if this is a problem with the system not pressurizing, it just seems odd to me. It runs at a cool 180*. It doesn't even puke out the overflow.

_________________
Brian Long

What are you using to pressurize your system ? A hand pump type tool ?

I always pressure test my cooling system after any work on it to look for leaks; I run it to 15psi and let it sit awhile; the test manual says that if it drops less than some number of psi in so many minutes, that's OK - I forget the #s offhand.

For me, if a system filled with *air* drops less than 5psi in 10min and I can't see any problem, I call it good enough and then put coolant in. After the systems have been filled & run awhile, I often see the drop <1psi in 20mi. There's a big difference between a system filled with air and one mostly filled with coolant - air will flow much faster and through tiny leaks that liquid won't.

I've found that the thermostat gaskets I used (Felpro and others) are rather porous to air when they are new, even when heavily coated with sealer. After they get used & soaked awhile, they get pretty much airtight.

Also, Chrysler factory radiator caps have a valve in the center that was normally hanging open and closed only upon sufficient flow; many aftermarket caps have the same valve held shut with a spring. Both work OK.

Could be the heater core is bleeding off pressure. To check, take the heater core out of the picture by bypassing it with loop back to the water pump. Also a poor fitting cap or, a crack in top tank above coolant level is preventing proper pressure building in your cooling system.

If the coolant level is about an inch and a half below the radiator fill neck it won’t puke out the over flow.

180 degree thermostat is OK, but 195 degree is preferable for an every day driver. Warmer block promotes better cooing (it’s a delta T thing), and less chance for sludge production problems.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC