Twibs415

iTrader: (8)

im not sold on that statement. fwiw ford sells heater core restirctors. iv personally blown out 2 heater cores until i drilled holes into my t-stat

deezums

iTrader: (3)

Then you've lifted the head and the rest of your coolant system is **** and inoperable, mainly the overflow and cap.

Or you bought a ford, you should not do that.

Twibs415

iTrader: (8)

^lol ok

aidandj

iTrader: (5)

No holes in thermostat, heater core intact.

ryansmoneypit

iTrader: (6)

I have yet to explode a heater core. Ever. In my life. I've never drilled a single thermostat.

18psi

iTrader: (76)

he was racing dom for his pink
blew the welds on the heater core

deezums

iTrader: (3)

I have no idea how fords work, but the pressure in the miata heater core should be about neutral at all times. In stock form it's set up to shunt 100% of the available flow from the water pump.

Therefore, the only way it could ever pop would be pressure, not volume which would best be controlled by a restriction on the inlet. In fact, doing so would place a restriction on the water pump and increase pressure or cause cavitation from unnecessary inlet vacuum whenever the thermostat were closed.

Ergo, if it pops other components of your coolant system failed or you built a shitty cooling loop. Pretty sad really, because it's so ******* easy.

lol

bbundy

The heater core is not as effective at removing heat as the radiator.

bbundy

FWIW i run a thermostat in the heater core line just after the heater core. As coolant exiting the heater core exceeds 160 F it starts shutting flow through the heater core down. At 180 F it shuts about 95% of the flow through the heater core off sending more flow to the radiator.

aidandj

iTrader: (5)

So like a reverse thermostat?

Joe Perez

iTrader: (8)

Google bypass style thermostats.

aidandj

iTrader: (5)

bbundy

It's a remote oil cooler thermostat. I changed the wax plug in it to a much lower temp value and plumbed it to operate like that.

Twibs415

iTrader: (8)

My car has nothing coming out of the front of the head and its a begi style reroute so when its cold i only have coolant going through the heater core and through the oil cooler. All i know is that drilling the hole fixed my problem. The heater core was the only thing letting go the rest of the cooling system was new and functional.

Also all the m-tuned/rebranded reroutes iv installed had removed giggle pins with the holes enlarged.

bbundy

The Miata water pump is not so much a positive displacement pump it will churn away like crazy and not build much pressure even if the system is fully blocked. I don't buy that as what cured your problem. Guys that enlarge the bypass hole are usually doing so because they don't have a heater core circuit for flow to bypass at all and it reduces the rate of temp rise.

The only way you are going to pop stuff is either from thermal mechanical fatigue with too many heat/pressure cycles or you over pressurize the system which generally happens with a head gasket or head issues.

Jumbosrule

Pulled the figure from 949's site for the standard M-tuned routing schematic



And revised it to show the change I made to the system using the green line. So the water in the section of hose from the back of the head to the T-stat is no longer static, which means the T-stat directly sees the temperature of the water as it comes out of the motor.



Going back to the first page - the static column of water is not ideal because it takes a while for convection to do it's job as compared to flowing directly over the T-stat. I'd rather that T-Stat open as soon as the water is up to temp rather than letting it spike over temp (inside the motor) until the hose column heat soaks and triggers the T-stat, only cooling back down after that point.

The size of the hose isn't changing; only the location of the outlet so I would not expect any increase in pressure or volume to the heater core beyond what it is already seeing with the standard coolant reroute.

Joe Perez

iTrader: (8)

Since others have been muddying the thread with tangential discussion, I'll re-state that your logic and execution are both sound.


This business of "increased pressure on the heater core" makes little sense. The heater core is already being exposed to a pressure differential of around 14 PSI (or whatever the venting pressure of the radiator cap is), and there's unlikely to be more than a pound of difference (if even that) placed across it by the flow of whatever trivial volume of water that tiny little impeller in the coolant pump is producing*. And, at any rate, said flow will be roughly comparable regardless of the relative locations of the thermostat and the heater core inlet/outlet, for any reasonably sane cooling-system configuration. (eg: one which has a thermostat, a bypass, a mixing manifold, etc.)


* = I can't seem to find any sources here which tell me typical flowrates through or differential pressures across heater cores in automotive cooling systems. If anyone knows of data, I'd be curious to see it.

aidandj

iTrader: (5)

Yes. your modification was correct. Your original explanation was either confusing or incorrect.

bbundy

Sound logic themostat will be a little more responsive.

codrus

While I agree that the new coolant path is theoretically better, I have the as-shipped M-tuned reroute on my car and it works fine. There's no apparent delay in opening the thermostat, if there were then datalogs would show the coolant temp spiking above the thermostat temperature before dropping back to where it's supposed to be, and they don't. So sure, it's theoretically better, but I don't think it's worth the hassle of modding the remote thermostat housing.

--Ian