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Matt Hardy
Matt Hardy, ASE Certified Technician
Category: Dodge
Satisfied Customers: 920
Experience:  ASE Master Auto Tech, ASE L1, Jeep/Chrysler Dealer Tech, 18 yrs exp
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can a bad water pump cause heater to not work

Submitted: 7 years ago.
Category: Dodge
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Jerry, Master Mechanic
Satisfied Customers: 17155
Experience: ASE Master tech, 30 years exp. troubleshooter, driveability tech
replied 7 years ago.

Hello and welcome to Just, Super mechanic here. About your vehicle.


Actually, if the system is not building up the proper pressure, the coolant can't circulate the way it should and that can have an adverse effect on the heating system. You will want to stop the water pump leak, (replace it) and make sure that the radiator cap is holding pressure, (15psi)

Customer reply replied 7 years ago.
If the pickup doesn't overheat wouldn't that mean the water pump is still moving water? Fixing the heater is my main objective I will replace the pump when I know for sure it is leaking and have some time. Is there any other reasons the heater might not be working?
Jerry, Master Mechanic replied 7 years ago.
Sometimes too much pressure will not allow the coolant to circulate. You will want to be sure that it is building up to about 15psi and not much more. Also that the engine temperature is at least 190F.
Customer reply replied 7 years ago.
Why would it put out hot air on recirculate and not on defrost?
Jerry, Master Mechanic replied 7 years ago.
Ah..that sounds like it may be a problem in the heater box. I have never run into that type of problem with one, but wait, I am sure someone here has. Let me open it back up and see. No need to reply, someone should be along shortly, I'm sure. Thank you for your patience.
Matt Hardy, ASE Certified Technician
Satisfied Customers: 920
Experience: ASE Master Auto Tech, ASE L1, Jeep/Chrysler Dealer Tech, 18 yrs exp
replied 7 years ago.

Try this method to bleed air from the cooling system:

  1. Get an extra radiator cap.
  2. Cut the smaller seal (the bottom one) and remove it from the cap.
  3. Install this modified radiator cap on the radiator and run the engine. You can also drive around locally.
  4. The missing seal will allow air to escape into the overflow bottle, and coolant will be sucked into the radiator.
  5. Watch for bubbles in the overflow bottle.
  6. Keep the overflow bottle full of coolant.
  7. Be sure to install a good radiator cap when done.

Hopefully this will help!

Matt Hardy, ASE Certified Technician replied 7 years ago.

Thanks. Reply back here with any new info.

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