Odd cooling issue. Would appreciate input

[MikeyM]

Hi all,

69 Bee with a 383, 22" radiator, no AC. The car runs and cools fine except at idle in hot weather, it starts to creep up. I will be installing a shroud soon but my questions are:

- Why does the temp gauge go up when the engine is turned off? Is this just residual heat going into the coolant?
- Why does my standard (non-lever type) radiator cap burp coolant out of the very top? I have an overflow bottle installed but the coolant doesn't go down the hose to the bottle.. I've confirmed it's clear.

Thanks,
Mikey

 

[RR Fan Dan]

Where does your cap burp fluid? Temperature goes up when car is shut off due to residual heat and no cooling flow. Temp goes up at idle because no airflow across the radiator and reduced coolant flow because water pump is not spinning at a higher rate.

 

[eldubb440]

after shutdown, the hottest coolant rises to the top

 

[j-c-c-62]

Temp goes up at idle because no airflow across the radiator

Nor the across the engine itself. An engine radiates by itself a decent amount of heat. Another factor often overlooked, heat takes time to travel. When an engine is ioperating, there can significant internal hot spots that generate heat. When the system is operating normally, the amount of heat being removed is equal to the heat being generated and that is flowing. When engine/water/fan all stop, the heat is still present and continues to flow, so cooler surfaces that where present when everything is running normal, keep absorbing the flowing heat and their temp rises. When that temp rises enough that the temp differential is great enough (delta), the system stabilizes and starts to slowly cool at the new higher temp and rate.

 

[RR Fan Dan]

Nor the across the engine itself. An engine radiates by itself a decent amount of heat. Another factor often overlooked, heat takes time to travel. When an engine is ioperating, there can significant internal hot spots that generate heat. When the system is operating normally, the amount of heat being removed is equal to the heat being generated and that is flowing. When engine/water/fan all stop, the heat is still present and continues to flow, so cooler surfaces that where present when everything is running normal, keep absorbing the flowing heat and their temp rises. When that temp rises enough that the temp differential is great enough (delta), the system stabilizes and starts to slowly cool at the new higher temp and rate.

You are correct. I was trying to keep it simple.

 

[1STMP]

Stock or aftermarket aluminum
radiator?

 

[Lefty71]

I know this doesnt answer your questions, but it is worth noting, since you said that you'll add a shroud soon, that any part removed from the cooling system in your car is going to have a play in this problem.

Ive seen dicussions over the years, especially in the C body forums regarding cooling issues from the get go, up to and including the bean counters at the corporate level trying to save a buck in the radiator department. While you may find that to be a stretch, i can assure you that if your car came with a shroud and also rubber trim designed to channel air from the bumper area to the core support, you will see a rise in temperature if these items are altered or removed.... The engineers job does include doing his best with the materials and methods alloted to him.

 

[OMTWF-72SE]

If your cap leaks thru the rivet it has failed, if it is a smooth top there is only 1 place coolant can go, past the gasket at the neck (failed spring) and/or a issue with the overflow. Possible a little of both.

 

[1967coronet]

Most all cars will have a rise in coolant temps when 1st shut off.
If you have a clutch fan test the clutch.
The shroud will help.
Also buy yourself a new 15# cap and when filling the radiator leave the coolant level at least 1 " to 1 1/2 "below the radiator top.

 

[69 Sleeper Bee]

I have the same exact setup as you and no issues. I would look at a new cap first.
When you say the temp creeps up, to what ?