Running white hot

-
I'm sure someone with more experience will have a better idea, but... I've had my slant run pretty hot when the carb was set too lean but I don't remember the manifold getting white hot.
 
What are you working on
What year
What engine
What modifications
Has it always done this
If not what changed right before this started.


If the exhost manifold was painted the white is just the paint burning off.

As for boiling at shut off, a couple issues.

  1. If the rad cap is defective, or too low a pressure, the wrong type
  2. If there is air in the system.
  3. If the thermostat is installed backwards, bad, or stuck closed .
  4. If there is incificiant air flow through the radiator
  5. If the rad is clogged
  6. If the water pump is defective.
  7. If passages inside the block are clogged
  8. A bad head gasket

The list goes on.
 
Last edited:
Manifold was painted blue so maybe that’s the white? Didn’t know it changed when heated... It’s a slant 6 225, 1972 no mods, all stock as far as I know.

As for the cooling system I haven’t changed a thing since I got it so it could be a myriad of those ideas. I’ll probably start with the thermostat just to validate it works
 
Get an IR gun and see how hot it's really running.
 
Many paints turn into white powder residue when exposed to the heat of an exhaust manifold.... What ever you do don't snort it... :lol:
 
Pull your spark plugs and see what story they tell.
does your exhaust manifold have a counterweight baffle?
 
Mine was runnning hot when I got it. Float was set wrong, heat riser stuck, along with stuck wieghts and blown vacuum canister in the distributor. Looking back I'm amazed the poor thing even ran. Do vefity temp guage is working properly.
 
If the distributor loosened up and timing is way retarded it will put lots of heat in the exhaust and the cooling system.
 
72smallairparticler said:


Bubbling coolant and white hot exhaust manifold ‍♂️
Click to expand...

The manifold isn't "White hot" Objects take on a dull red glow around 1100F but cast iron melts at 2200. You need to do a cooling system pressure test and check the cap for starters. As mentioned, make sure the heat riser is open when the engine is warm. Like Rusty mentioned, a non contact thermometer can be an effective tool to check block and hose temps. Say that the block near the thermostat is 230 F and the hose going to the t stat is 100F and the engine has warmed up, you probably have a stuck thermostat.
 
Get a real temp reading..
And I'll be that guy , please be careful, we had an upper rad hose blow off an overheated car my dad and I worked on ( without a proper temp gauge)
and it cooked him from the waist up like a lobster.
 
On a cold motor check your heat riser flapper. Triangle lever looking thing on left side of exhaust manifold right under carb. It should pivot easily and actually bounce once it's wound against its spring. By default a cold riser valve will be in the 'blocking position', diverting the exhaust up to the bottom of the heat stove under the carb. When the manifold gets hot, the spring relaxes and pulls the riser position to the bypass position directing exhaust straight down the manifold to the head pipe. If it's stuck up in the cold.position it will really heat that intake up, not good. A lean carb (intake leak) will cause a hot combustion chamber/motor as well. And of course a sheared/rotted impeller or rad blockage/frozen Stat will cause a motor to run hot.
 
You must log in or register to reply here.
-

Back
Top