Very low cooling pressure

[justthatguy]

I recently had to pull the radiator out of my 72 Newport. I put it back in, bled it, and I seem to have an air pocket trapped however I can't seem to find it. No leaks, the heater hose has coolant, I have reasonable heat, it's a brand new cap, radiator, new fan clutch, it doesn't overheat, and I have an overflow that's neither low nor overly full. It will pressurize slightly but not firmly. My temp gun says 175 to 184 so I know the tstat is good and cycling, considering at least it has a new one in it.

I burped it by parking on an incline and slowly filling til full, then squeezing the hose until I can no longer feel bubbles.

I can buy a high capacity funnel and try to burp like that but I've never had this methodology fail me. Any ideas as to what gives?

 

[70bigblockdodge]

Sounds normal to me. Low temp equals no steam pressure with really no need. Top tank would normally run 1/4-1/2 full, but overflow tank should catch overflow on warm up and fluid from the tank will siphon back in as it cools. Allowing for less monitoring of coolant level maintaining proper level

 

[Toolmanmike]

Run it/drive it. If there's air in there out it will come out. Sounds like it's working properly.

 

[CBODY67]

No real place for an air pocket to get trapped in those engines/cars. Look at the radiator tank level compared to the rest of the engine. It's the highest place in the system. Any coolant recovery system should have the lines close to that level, too, for things to work correctly.

You can seek to keep the upper tank full, but everytime you remove the radiator cap, it spoils things as it allows more air back into the tank, which you're seeking to prevent. Been there, done that! No real performance (heater or otherwise) difference as the systems were designed to compensate for the upper tank being about 1/2 full, as mentioned.

I know that it can be hard to not remove the radiator cap to check the level. Been there, done that. But once you get the radiator tank as full as it can be, with the engine COLD, then fill the coolant reservoir to the "COLD" level or a bit above, and monitor the level in the jug over the next few days/hot-cold cycles. After a while, you'll see (or shoiuld see) a somewhat consistent level for hot and cold engine temps. Should you remove the cap with the engine cold, then to get things back to where they were, you'll need to squeeze the upper radiator hose to get the air that's now in the tank and lines to the jug purged again.

With the weather we're having now, not the best time to get the coolant recovery systems to operate as designed, especially with a short-trip/drive cycle possible orientation.

You mention "reasonable heat" from the heater. What temps on the heater hoses to the heater and at the bottom floor vent (over the trans tunnel)?

Enjoy!
CBODY67

 

[justthatguy]

As I recall I think it was ~130 out of the top vent. The car has never had fantastic heat for a number of reasons but it's fairly steadily always this temp.

I'm just used to having firm hoses, it seemed a little odd to me.

 

[Toolmanmike]

You would need to pressure test the cap. Even though it's new doesn't mean it's right. A radiator pressure tester with the cap adapter is the way to test it. That's how the system pressure is protected.