Coolant flow direction
 

Hey Gang,

Any idea which direction coolant flows in our engines, does it flow from bottom to top or top to bottom. I am asking because my coolant temps rose to 221 degrees ( normal is 180*-190*) this morning with an ambient temp of 64 degrees while traveling at 70mph.
Once I got my car in the garage I used my infrared temp scanner to measure the temp differential between the upper radiator hose and the lower radiator hose. The upper hose read 200* and the lower hose read 115*, I'm not sure if this old trick for detecting a faulty thermostat works for our cars but I'm inclined to believe the thermostat is to blame. My car btw is a cammed 05 A4 running a 180 degree thermostat.
Thanks in advance for any insight you all may have.

I believe the top goes to the radiator and the bottom leaves the radiator. Not for sure though.

lower radiator to thermostat to block to heads to water pump outlet to upper radiator

How does that work? The thermostat is in the water pump port that goes to the lower radiator. If the lower radiator hose is the outlet the cooled coolant hits the 195 degree thermostat as soon as the thermostat opens and the cooled coolant will quickly close the thermostat again. Thus the thermostat would oscillate from open to closed and back very quickly. There wouldn't be much coolant flow that way. The way it is supposed to work is hot coolant opens the thermostat and then flows past it to the radiator. Once the coolant passing through the engine is cooled sufficiently the thermostat closes again.

I suspect the thermostat being in the water pump port to the lower radiator hose indicates the coolant flows into the right side of the radiator.

Here is what the SM says about coolant flow:
Cooling System Description and Operation
Cooling Cycle
Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. Some coolant will then be pumped from the water pump, to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.
Coolant is also pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where it absorbs heat.
The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.
Coolant is also directed to the throttle body. There it circulates through passages in the casting. During initial start up, the coolant assists in warming the throttle body. During normal operating temperatures, the coolant assists in keeping the throttle body cool.
From the cylinder heads, the coolant is then forced to the thermostat. The flow of coolant will either be stopped at the thermostat until the engine is warmed, or it will flow through the thermostat and into the radiator where it is cooled and the coolant cycle is completed.
Operation of the cooling system requires proper functioning of all cooling system components.

Bill

I have an EWP so my t-stat is on the top hose. I guess mine is backwards.

And it does, it just isn't telling you which end is the radiator outlet,

Two sources I found were from MSD and S&P and a schematic


scroll down to pg 7

http://www.hotrodlane.cc/PDFFILES/60biscayne.pdf



again, scroll down

http://www.msdfuelinjection.com/pdf/frm28799_mefi4.pdf

"These new engines incorporate a water pump that spins opposite of the crankshaft. The water enters the pump from the side and exits the engine out the top. The thermostat is located on the inlet of the pump instead of on the exit on old small blocks."

See post #7 schematic
http://www.ls1.com/forums/showthread.php?p=2144163

Good job on your research. Pretty much answers anyone's questions. What we have to realize is these LS engines are the opposite of 99% of all other engines out there when it comes to thermostat placement.

Placing the stat at the pump inlet obviously works but is the reason why the actual running temp of the engine is so much different (higher) than the stat rated temp.

"This makes the engine run warmer for a given thermostat. For instance, a 160°F thermostat will not open when the engine temperature gets to 160°F. It will only open when the incoming water gets to 160°F. So if you have too much air moving through the radiator the thermostat may not open until the engine is 175°F or so. Keep this in mind when selecting a thermostat."

I love what mtspro6 on the LS1.com forum example you posted says and then after the others present their info he never comes back.

"Listen, i'm only gonna explain this one more time. I don't care what you read about aftermarket waterpumps or anything like that. The thermostat is the OUTLET. Period." and "I have no idea where you got that information but obviously you do not understand how cooling systems work. That page is absolutely incorrect. My information was cut and pasted from general motors service information. What in the hell do you think a thermostat does when cooled antifreeze passes by it? It CLOSES. So how would it cool the engine if it was closed? Magic? Three wishes? sheesh. If i gotta put a clear hose on one of my cars here and run a video of how it works, i will. Not trying to get into a pissin match with ya but damn. Your page is wrong. wrong, and wrong."

Never say never!

That schematic seems to be from an LS1. Anyone have one for an LS2/3 ?

Common sense says the hose with the thermostat is the outlet from the engine to the radiator.

Coolant reaches 195°, thermostat opens, water flows to/thru the radiator and then back to the engine where it gets heated again.

Have a nutter butter peanut butter cookie

pretty pic w/caption

http://www.chevyhiperformance.com/te.../photo_06.html

Then I guess you ain't got it

GM manual for 07 says radiator outlet hose is the lower hose. This hose leads to the thermostat housing. And going by what Bill says "Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump"

I'd still say the thermostat is the inlet

Nice research. Your link to ls1.com, post #7 is crystal clear, the thermostat is the INLET side of the engine/cooling system. The schematic leaves no doubt.

:thumbs:

Hey, glenB you win the 64K dollar question. A well credentialled Vette service tech in my area validated that the thermostat is the inlet. Turns out my problem was indeed a faulty thermostat. Thanks again.:thumbs: