Heater Cores

**sil80 1J** · 01-05-2008, 01:11 PM

Does anyone know whether the heater tap comes before the core to control flow or after? it would make sense its before but ive been told otherwise. Does anyone know for sure?

**Hiro** · 01-05-2008, 02:46 PM

Before, otherwise if you have a leaky core it'll just continually dump hot coolant into the passenger-side footwell no matter what setting the tap is on. The tap usually sits on the firewall on the coolant line running into the core. If the tap is off, it returns the coolant back into the cycle, if it's on then it allows it into the core.

**sil80 1J** · 01-05-2008, 07:36 PM

just as i suspected, very good point about the leaking core, thanks for your help mate

**Draven** · 01-05-2008, 11:36 PM

if it were after you'd have to wait for the coolant in the core to cool before the heat went away, which would be crap

**MWP** · 02-05-2008, 12:12 AM

Some odd theories in here....

Originally Posted by Hiro

Before, otherwise if you have a leaky core it'll just continually dump hot coolant into the passenger-side footwell no matter what setting the tap is on.

It would leak no matter which side the tap is on... pressure in the cooling system will make it leak even if the tap was before as there is no one-way valve.

Originally Posted by Draven

if it were after you'd have to wait for the coolant in the core to cool before the heat went away, which would be crap

Its the same if the tap is before too... turn the tap off, the hot coolant in the core still gets dissipated.

**Mos** · 02-05-2008, 12:49 AM

Originally Posted by Hiro

If the tap is off, it returns the coolant back into the cycle, if it's on then it allows it into the core.

If it did that it would need 4 connections. A closed tap allows no coolant flow - it does not cycle it back around the core, it just shuts that circuits.

Originally Posted by Draven

if it were after you'd have to wait for the coolant in the core to cool before the heat went away, which would be crap

Where's the heater tap in my loopra busting IS400?

A lot of cars don't use heater taps and run a full flow heater core. The amount of heat is controlled by the amount of air passing through the core, and not the amount of water.

Just ask Matt about his leaking core in his IS250

Mos.

**The Real Roadrunner** · 02-05-2008, 02:22 AM

Originally Posted by Mos

Just ask Matt about his leaking core in his IS250

Mos.

talking about that i better fix it now that we are going into winter, shrivle much

**sil80 1J** · 02-05-2008, 08:32 AM

well as you can tell from my nickname im putting a 1j into my sil80 so does anyone know which way a 1j flows for sure and does anyone know if a 180sx runs a heater tap or not, i cant find one in the engine bay, nor is there a control cable or vacuum solenoid for one so im assuming it either doesnt run one as said earlier or it is internal which doesnt make much sense to me.
thanks for all the info guys!!!

**Hiro** · 02-05-2008, 09:51 AM

Originally Posted by Mos

If it did that it would need 4 connections. A closed tap allows no coolant flow - it does not cycle it back around the core, it just shuts that circuits.

Sorry, got confused (was half asleep, despite the time). In the future, probably shouldn't try to think of the plumbing on my AE82 as it currently has the heater core completely bypassed (either 'cause the core leaks, or the whole heater box itself is rusted out)

Probably look at getting that fixed soon too, weather has been getting quite cold lately