So how do you change the heater hose nipple?

[someotherguy]

I'm no cooling system expert, nor hydraulic expert.. but aren't pressurized liquid systems kinda hydraulic systems?

There's a small amount of debate on whether the restrictor is needed. Not all vehicles use a restricted fitting. Some have used a regular hose barb (I have) and had any issues. In that thread I do mention my '94 5.7 had some audible gurgling in the heater core but it turned out to be air in the system due to a slow intake gasket leak. Once I did the intake gaskets, no more gurgle.

Richard

 

[isle_cruiser]

I'm no cooling system expert, nor hydraulic expert.. but aren't pressurized liquid systems kinda hydraulic systems?

100% ... I just didn't want to create an argument haha

Doesn't matter the hose size or orifice size. Pressure is still the same within a closed system

 

[PlayingWithTBI]

Doesn't matter the hose size or orifice size. Pressure is still the same within a closed system

Yeah, we had this discussion a couple years ago - Pascal's Law FTW

Back to

 

[DeCaff2007]

The Dorman part is restricted just like OEM.

What do you mean by "restricted"?

 

[someotherguy]

What do you mean by "restricted"?

You need a special license to purchase them.

Have you really not been reading along in the rest of this thread?

Richard

 

[Caman96]

What do you mean by "restricted"?

That’s Restricted Information!
Lol, sorry, had to.

 

[Caman96]

What do you mean by "restricted"?

The nipple has a inside ID of about 1/4”.

 

[Schurkey]

Doesn't matter the hose size or orifice size. Pressure is still the same within a closed system

ABSOLUTELY TRUE...in a STATIC system.

Cooling systems are not static when the engine is running. There are TWO sources of pressure, and a thousand sources of restriction, the primary one being a closed or partially-closed thermostat, and another being the restricted quick-coupler for the heater core.

First source of pressure: Radiator cap. With the engine hot but not running the system will have the rad-cap pressure EVERYWHERE. When the engine is NOT running, the system is STATIC.

Second source of pressure: Water pump. The pressure at the water pump outlet (pressure side) will be higher than at the water pump inlet (suction side). COOLANT FLOW CHANGES EVERYTHING. The system is now DYNAMIC.

The engine water jacket, restricted gasket holes, casting flaws, heater core, connecting hoses, radiator water tubes, etc. all have some amount of resistance to flow...but the closed thermostat is king.

Consider the outlet and inlet of the water pump with the engine running: The outlet into the block will be the rad cap pressure PLUS the water pump pressure. The inlet into the pump will be rad cap pressure MINUS water pump suction. Both the pressure and the suction increase with a closed thermostat, but still exist with an open 'stat.

The heater core is fed by water pump pressure somewhat reduced by the restrictions in the engine coolant jacket, restricted head gasket coolant holes, etc. But the big restriction will be the quick-coupler that chokes flow down to 1/4" approx. OTOH, the heater core outlet will be into the water pump suction side directly, or perhaps into the "cool" radiator tank--which is connected to the water pump suction side by the lower rad hose. Water pump suction reduces pressure in the heater core that can't be recovered due to the partially-blocked (restricted) flow through the quick-coupler.

This whole system is not unlike an A/C system, where the orifice tube or TXV produces a restriction that drops pressure, and the pump (compressor) therefore has low pressure on the inlet (suction) side, and high pressure on the outlet side.

What do you mean by "restricted"?

Interior passage reduced to approx. 1/4".
Visible in this photo--lower left corner:

You must be registered for see images attach

 

[PlayingWithTBI]

The heater core is fed by water pump pressure somewhat reduced by the restrictions in the engine coolant jacket, restricted head gasket coolant holes, etc. But the big restriction will be the quick-coupler that chokes flow down to 1/4" approx. OTOH, the heater core outlet will be into the water pump suction side directly, or perhaps into the "cool" radiator tank--which is connected to the water pump suction side by the lower rad hose. Water pump suction reduces pressure in the radiator that can't be recovered due to the partially-blocked (restricted) flow through the quick-coupler.

Not really. 1st thing we need to agree on is there's no air, which is compressible, in the system (water is not). In my 88, the return line to the radiator is just below the cap so (not the "cool" side, that's the bottom of the radiator), it's seeing the same pressure as flow coming from the water pump, when the T-Stat is open. If the pressure going through the heater core, was lower, the pressure from the radiator will apply too much backpressure, thus stop flow though the heater core. The only reason for the restricted fitting is to help the heater core supply heat to the cabin when the T-Stat is still closed AND help the engine warm up quicker with less flow back to the radiator, again until the T-Stat opens up.

And Pascal's Law does apply to any sealed system, whether static or dynamic.

Edit: I need a drink!

 

[Supercharged111]

Not really. 1st thing we need to agree on is there's no air, which is compressible, in the system (water is not). In my 88, the return line to the radiator is just below the cap so (not the "cool" side, that's the bottom of the radiator), it's seeing the same pressure as flow coming from the water pump, when the T-Stat is open. If the pressure going through the heater core, was lower, the pressure from the radiator will apply too much backpressure, thus stop flow though the heater core. The only reason for the restricted fitting is to help the heater core supply heat to the cabin when the T-Stat is still closed AND help the engine warm up quicker with less flow back to the radiator, again until the T-Stat opens up.

And Pascal's Law does apply to any sealed system, whether static or dynamic.

Edit: I need a drink!

Orrr, maybe it's also part of the secret sauce that prevents these trucks from overcooling in the dead of winter?