Thermostat comparison

With this water cooling design, I doubt any water really flows through that air vent hole, as the bypass back to the block is open until the t stat actually opens to the radiator and the lower disc starts to close off that bypass.

You need a pressure differential across the t stat to get flow, and I don't think there is a pressure differential with this T stat closed.

Unlike a Chev, for example, where the pump dead heads against the T stat until it opens because there is no bypass (other than a small passage in the WP itself). You can run a Chev without a Tstat,and it will pump mass quantities of water through the rad, if you remove the T stat in an Fcar, no water (or very little) goes to the rad.

Doug

 

Doug, wouldn't the temperature delta of the coolant on either side of the tstat (prior to its opening) cause a pressure differential? Most header tank caps are set for between .9-1.1 add'l atm above ambient atm, for example, in order to keep the boil over point down (=pressure).

 

There is always flow at the back of the thermostat whether it is closed (main orifice) or in bypass (extension plate) closed mode. We don't just wait for heat propagation (convection) to open the thermostat. But you are right, probably very little gets through... Where I live (sunny 80 degrees yesterday) it probably makes no difference. But for folks who live in the high latitudes, every little bit helps. Location could add 50+ degrees to the imbalance this time of year. Knowing what has been published on the subject, if I lived in high latitudes I'd be inclined to open that hole (shock or vent, your call) even further... 3/16"?

Folks, lets not get caught up on semantics... Mike was right. It was/is an air bleed hole - or at least it started its life that way. But over the last 10-15 years engineers have found it has other benefits and we should be grateful Ferrari had the foresight, wisdom or just dumb luck to employ it when they spec'd out their thermostats.

Rick

 

Temperature increase will cause a pressure increase, but it is uniform across the system, a pressure increase in the block due to temp increase would just cause the pressure to increase in the radiator back through the radiator return line and also on the cold side of the T stat for the same reason.

If you have a 100 foot long closed pipe that is filled with water and heat one end, the pressure in the pipe will be constant everywhere, even if water is boiling at one end and almost frozen at the other.

There is obviously some small amount of flow through that little 1.5MM hole (approx), but I do not believe enough to warm the fluid in the radiator, as the radiator is a long way away, with down pipes and horizontal pipes and up pipes and return pipes.

The T stat doesn't slam open when it gets to whatever opening temp it is set at, it starts to gradually open, slowly letting warm water go to the rad,and slowly mixing cold return water with the warm water from motor jacket.

Doug

 

Now I'm forever going to visualize you as Gene Wilder in Willy Wonka... <grin>

Rick

 

Just ordered a t-stat via B-man's link in post #43.... it is a legendary heat wave here in NYC so it is timely to hit the cooling threads..... I hope the link still points to the right t-stat that b-man got... since if I put " 056 121 113 " inthe web sites part number search engine ... itactually pulls up a different whaler t-stat... but I will still stuck with b-man's page link'd t-stat.... ( how's that for confidence!), b-man if I ordered the wrong one ( e.g they changes the page link) please stop me before Iinstall it and wreck my engine with a aftermarket t-stat..

 

Ok confused... Which do we use in the 308 qv?
The thermo that is in ther now is the Behring. , I got the whaler 113F. Not 113 A.

Are they the same ? What is cheapest source for the Behr .?