Heater core hoses

Tiny
BUCK211
  • MEMBER
  • 1990 DODGE DAKOTA
  • 3.9L
  • V6
  • 2WD
  • AUTOMATIC
  • 218,000 MILES
I actually have two questions. #1. I was wanting to know which of the two hoses running through the firewall is inlet hose to heater core? Is it the top or bottom? #2. Which direction should the heater control valve arrow face? Towards the firewall or the radiator?
Do you
have the same problem?
Yes
No
Wednesday, January 11th, 2017 AT 7:59 PM

8 Replies

Tiny
JOHNNY G.JR
  • MEMBER
The hotter of the two would be the inlet. Use an infrared thermometer to find out if you get no more responses here.
Was this
answer
helpful?
Yes
No
+1
Wednesday, January 11th, 2017 AT 9:06 PM
Tiny
BUCK211
  • MEMBER
They were both warm to the touch. So I am not sure about which is inlet and outlet.
Was this
answer
helpful?
Yes
No
Wednesday, January 11th, 2017 AT 9:16 PM
Tiny
STEVE W.
  • EXPERT
If it has a heat control valve, that will be in the inlet hose. The arrow indicates the direction of flow. So the arrow would point away from the engine towards the heater core when installed in the inlet line.

As a general rule of thumb, a heater core with the same sized lines, you install the inlet hose on the fitting that feeds the bottom section of the core as that tends to push the air out of the core as it fills.
The return line fitting on the engine is 99% of the time the one closest to the water pump. That helps draw the heated coolant through the core providing better heat.

On a vehicle that has different sized heater hoses, the smaller line is the inlet side. That is done because the incoming coolant is under pressure. By increasing the size of the return line to the water pump it lowers the pressure in the core and makes it less prone to leakage, it also reduces the noise that the coolant creates as it flows through the core.
Another advantage to the different sizes is that during assembly, it is hard to mess up and install the lines the wrong way!
Was this
answer
helpful?
Yes
No
+1
Wednesday, January 11th, 2017 AT 10:22 PM
Tiny
JOHNNY G.JR
  • MEMBER
Steve thanks for putting more insight on this issue. I learned something new here.
Was this
answer
helpful?
Yes
No
Wednesday, January 11th, 2017 AT 10:39 PM
Tiny
BUCK211
  • MEMBER
Steve W and Johnny G. Thank you both for replying to my question. I greatly appreciate the information. I have been about to pull my hair out trying to fix all of the "repairs" (Lmfao) that previous owner did. I would not let that guy check the air in my tires. Lol. Again thank you both. I will post how repair goes.
Was this
answer
helpful?
Yes
No
Thursday, January 12th, 2017 AT 6:04 AM
Tiny
KEN
  • ADMIN
Glad we can help, please use 2Carpros anytime.

Best, Ken
Was this
answer
helpful?
Yes
No
Wednesday, January 18th, 2017 AT 1:24 AM
Tiny
BUCK211
  • MEMBER
Ty guys for the help. Sorry it's taken so long to respond, but life happens. Lol. I DID install the Heater control valve backwards. Smdh. I feel like a dumbass. All I had to do was open my eyes. Lol Ty though for the info, it is appreciated.
Was this
answer
helpful?
Yes
No
Thursday, January 19th, 2017 AT 6:45 PM
Tiny
STEVE W.
  • EXPERT
No problem Glad to help. Don't feel bad about the valve, I've done MUCH worse before.
Was this
answer
helpful?
Yes
No
Friday, January 20th, 2017 AT 1:07 PM

Please login or register to post a reply.

Recommended Guides