Not to get too fussy, but steam doesn't need a path to escape. It turns back
liquid water as soon as the temperature drops a bit or pressure is increased,
If you have a steam bubble forming on the wall of a wet sleeve as soon as it
gets away from the wall it almost certainly collapses. If you're seeing steam
in the tanks it's only because you've opened the cap and dropped the pressure
low enough to cause boiling. Steam is water in it's gasous state.
Trapped air is a different story.
On Mar 18, 2013, at 2:57 PM, "Greg & Alison Blake" <ablake2@austin.rr.com>
wrote:
> John,
>
> One of the short comings of the TR3 and TR4 cooling system design is the
> inability of steam to escape the system. Once formed, it creates hot spots
> and air has replaced water in the area steam has formed if you don't give
it
> a path to escape. The fact that the thermostat housing is typically the
> high point of the system doesn't help. Another problem is lack of flow to
> the back of the head and to piston #4.
>
> I started down a similar path as you suggest. I assumed that if I routed
> hot return water back to the suction side of the water pump (return heater
> port) I'd be recirculating hot water and this would be bad. So for my
> system, I installed a expansion tank with a 22-25 psi cap on the firewall
> routed the heater supply (port on back top PS of head) to the top side port
> of the tank and routed the return line from the bottom of the tank to a
> fitting I installed between the thermostat housing and the intake of the
> radiator (I run a Chevy style cross flow radiator read more later). This
> allowed the hot water from the back of the block and head to return
directly
> to the radiator and be cooled prior to go back through the engine.
>
> This seemed like a great idea. I now had a place for steam to collect (the
> expansion tank) and I had increased the flow to the back of the head and
> block. Only problem was it worked too good. Even with a 180 degree
> thermostat, I could not get any heat into the engine it was running less
> than 120 degrees.
>
> The system simply bypassed the thermostat as all water was flowing from the
> back of the head through the tank and back to the radiator. I had bypassed
> my thermostat. I thought about playing with various restrictions in my
> return line but figured that the correct restriction would likely change
> based upon conditions.
>
> So I scrapped my idea and plumbed my return line directly to the heater
> return port. Works like a champ now.
>
> I mentioned that I use a Chevy style cross flow radiator. This design has
> several advantages to the top to bottom flow of our standard radiators.
The
> problem with a top to bottom design is that the radiator is seeing block
> pressure on the top of the radiator which means your radiator cap is seeing
> full block pressure, or very close to it. I have not put a pressure gauge
> on my block but I have read that block pressure can reach 30 psi. For this
> reason, some TR racers are always pumping at least a little water past
their
> caps on a top down style radiator. With cross flow, the radiator cap is
> kept on the suction (low pressure) side which allows a low rated cap, I use
> a 7 or 12 psi cap in the radiator, can't remember exactly.
>
> More on expansion tanks. Do a little research and you will find that most
> if not all modern cars run stem vent tubes from the cylinder heads or other
> high points to an expansion tank. A good example is the Gen III & IV small
> blocks.
>
> I also use a 1/4 npt drain valve on the top of the thermostat housing to
> vent all air out of my system when filling, this is very important. I use
> the expansion tank as the fill point and fill until the water leaks out
> through the open 1/4" valve. I prime the system a little by squeezing the
> house on the intake side of the water pump as I fill the system. Once all
> the air is out, I close the valve and fill the expansion tank to within
1/4"
> of the top. So far, one race weekend, I have had zero water pump past
> either of my caps with this installation.
>
> My dad is using this same setup but with a Wizard top to bottom radiator.
> He was getting a little water past the cap on the radiator cap and the
> expansion tank cap. He was using a 12 psi on the radiator and 18 on the
> expansion tank. He has replaced the caps for higher rated ones so we will
> see how it goes at ECR in May.
>
> Bob Kramer has been using this setup with a top down radiator for a few
> years. I think in a 15-20 min race he fills his expansion tank overflow
> bottle but he is using a lower rated cap I think it was 12psi. I have
tried
> to convince him to switch to a higher pressure rating on the expansion
tank,
> we shall see.
>
> Let me know if you want more information or pictures.
>
> Greg
> 04 TR3
>
> -----Original Message-----
> From: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] On
> Behalf Of John Wagner
> Sent: Monday, March 18, 2013 2:27 PM
> To: Fot@autox.team.net
> Subject: [Fot] cooling
>
> Amici
>
> I am thinking of running a tube from the heater outlet to the front of
> the engine.
> In past threads it said to connect it to the water pump inlet (heater
> return) that is just taking hot water and returning it to the engine,
> wouldn't it be better to plumb it to the thermostat housing and on to the
> radiator?
>
>
> Thank you
> Just the wrench
> John Wagner
> _______________________________________________
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