freegdr

Let me rephrase that when thermostats open it also act as a restrictor for heat transfer . To coolant flowing thru radiator in which heats extracted by air flowing across radiator fins.

salad

I think you're trying to say that if the coolant goes through the radiator too fast, the less heat is removed.

freegdr

Yep

djb383

The problem with that is, it's an old wives tale/myth. If coolant flow slows down thru the rad (cooling), flow also slows down in the block/head (heating).

I thought we were talking about overheating. Presuming the stat is wide open, it ain't causing overheating. Again, a wide open stat will flow more coolant than the pump can push. If the stat were to see overheat was no longer an issue, it will close.

The whole system is designed to "fight itself".......and it does a remarkable job. The stat tries to heat the motor up and the rad tries to cool the motor down.......and unlike some folks, the stat and rad reach a happy medium (normal operating temp range) 99.9% of the time.

http://www.stewartcomponents.com/tec...ech_Tips_3.htm

freegdr

Have you read this ....http://jeep-xj.info/HowtoRadiatorRestrictor.htm

salad

Interesting read, but I've never heard of anyone with that problem... djb383 is correct - if it ain't broke don't fix it.

freegdr

That's for sure.

djb383

Yep, I've read/seen that link post here several times. I think it's full of holes.

For example: Was not overheating but the temperature swung down from 195*F to 160*F every 30 seconds!

Think it did that when it was new?....not.....and it didn't come from the factory with a restrictor, did it?

Another example: The reason is that once the thermostat opens, you loose pressure inside the block which allows the coolant to boil off the side of the hot spots against your cylinders and inside the head.

Why would you loose pressure inside the block? There's a big 'ol hole beside the stat that allows coolant (and pressure if u like) to flow escape by the closed stat the moment the motor starts.

And another: The restrictor keeps the pressure higher as well as not letting the coolant flow too fast through the radiator so it has enough time to exchange the heat with the air passing through.

Again, if u slow down the flow of coolant thru the rad, u also slow it thru the motor. Yes, coolant will cool more the longer it stays in the rad but it also heats up more the longer it sits in the motor.

And another: The theory is not a new one as some Audi's and Fords came with restrictors in their heater hoses to increase the efficiency of the heaters.

We're talking about overheating....not my heater doesn't work.

And another: Well once the thermostat opened at the right temp, it just sat there idling with no fans at all ( I have twin electrics ) running with 24*C/75*F outside temperature.

Really????.....we're testing/experimenting on the cooling system in nice/pleasant/cool/no shirt and shorts 75*F outside temp weather.....WTF? In 75* ambient temp, a well maintained properly functioning cooling system should hold coolant temp very close to the t-stat rated temp.


The 1st sentence in the Stewart Components link I post says: We strongly recommend NEVER using a restrictor, they decrease coolant flow and ultimately inhibit cooling.
I hope the restrictors continue to work for those 2 guys in that restrictor link that say coolant can flow too fast thru the rad, thus causing overheating.

I'll just continue to put a little more trust in a engineering firm that has done extensive cooling system testing for those NASCAR dudes and passed along the "what works and what doesn't" info to us. They (Stewart Components) strive to increase coolant flow.