Big block cooling

-
D

Dusty1970

Member
Joined
Apr 25, 2017
Messages
20
Reaction score
26
Location
Dallas Texas
FA685A1B-16E0-4CFC-8A14-4549874CE201.jpeg


I have a Chrysler 400 from a 1973 Plymouth Satellite in my 70 duster. I bought the car with the engine already in it.
While testing the other day I noticed that the temp was about 200-215 on the top of the heads. About 145 at the TOP of the radiator at the hose and about 194 at the BOTTOM of the radiator at the hose. All was done with my temp gun. The car has a sending unit in the stock location and it reads about 20 degree higher than the one in the radiator itself.

question : if the flow is normally bottom to top, this doesn't add up. I believe I am using a stock pump housing and a high flow standard rotation pump.

should temps be lower at the bottom of the radiator?

thansk
 
  1. Water enters the top of the rad and is pulled down to the pump.
  2. Your measurements are totally normal
  3. You have no issues
 
Dana67Dart said:
  1. Water enters the top of the rad and is pulled down to the pump.
  2. Your measurements are totally normal
  3. You have no issues
Click to expand...
Then why isn’t the water at the top of the radiator hotter? It just came out of the engine. Then the rad cools it and it enters the bottom of the engine at its coolest point. Right? Thanks
 
Dusty1970 said:
Then why isn’t the water at the top of the radiator hotter? It just came out of the engine. Then the rad cools it and it enters the bottom of the engine at its coolest point. Right? Thanks
Click to expand...
Yes. My assumption is that where you are measuring is the issue.

Infrared temp probs don't work well on certain materials, like shiny surfaces.

There is another possibility...

The water pump is a later verity from a serpantine belt and is running backwards.
 
Just noticed you have a cross flow rad, that might help explain the odd seeming measurements.
 
Air in the system can cause everything you describe.
That upper rad hose looks tough to get all the air out of?
 
Thank you all for your replies.

I just can’t see a 55 degree difference from the top of the radiator to the bottom with the bottom being the hotter at about 200 degrees.

thanks
 
Dusty1970 said:
Thank you all for your replies.

I just can’t see a 55 degree difference from the top of the radiator to the bottom with the bottom being the hotter at about 200 degrees.

thanks
Click to expand...

Depends how the inlet and outlet align, and how fast the water is moving. The upper hose comes into the top of the tank - water could be rushing to the bottom of the tank and going straight across the bottom toward the outlet (to the pump). No idea if the end tanks are baffled, or have any other design features to prevent this kind of flow establishing itself - but it's definitely possible.
I'd be checking all over the core and seeing if you can 'map' the heat - or even get/borrow a thermal camera to see if there's anything to see.

Also, a hole in the thermostat won't bleed all air in all circumstances. That upper 'loop' in the rad hose could be trapping air in the system if it's the high point in the routing. Even without something like that, I often have to massage the rad hoses while filling to force as much air out as I can.
 
If you take the rad cap off before it's hot

Then let it idle till it is up to temp. You should be able to see the flow
 
Dana67Dart said:
If you take the rad cap off before it's hot

Then let it idle till it is up to temp. You should be able to see the flow
Click to expand...
Thanks, good idea. It was low a little from a leak. So I could see pretty good.

it was flowing from upper hose to the other side.
 
Dusty1970 said:
it was flowing from upper hose to the other side
Click to expand...

Assuming you mean flowing from passanger side to drivers side.

You said you have a tri flow (IIRC) so it would be from passanger side to drivers, down, then from drivers to passanger, down, then from pass to drivers side to the outlet.

If the outlet is on the passanger side then it is only a dual pass.
 
You must log in or register to reply here.
-

Back
Top