Incorrect direction of water flow may trap air in the heater core. Even if the hoses are reversed you should get heat, just less. If I recall correctly, the driver's side of the core goes to the connection closest to the radiator. (I would assume the water inlet would be the side with the control valve.) If both hoses are hot to the point that you can't hold on to one comfortably, it makes me assume there is maybe a vent door not working or an obstruction. If you have one of those heat measurement "guns" check to see if both heater hoses are about the same temperature. If they are, then it sounds like an airflow issue. Here is a general article with troubleshooting: http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/27-hvac-heating-ventalation-and-air-conditioning/86-heater-performance-diagnostics Thanks, Gary H. > -------Original Message------- > From: Bill M > > That's definitely backwards from how I have it plumbed up. I > could've sworn though that I remember somebody saying its bad to have > the output of the water pump going to the heater control valve as the > pressure will fatigue the valve. Don't know if that's right or > wrong > -- -- -- Please address private email -- email of interest to only one person -- directly to that person. That is, email your parts/car transactions and negotiations, as well as other personal messages, only to the intended recipient. Do not just press "reply" and send your email to everyone using the general '62-'65 Clubhouse public email address. This practice will protect your privacy, reduce the total volume of mail and fine-tune the content signal to Mopar topic. Thanks! 1962 to 1965 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html and http://www.1962to1965mopar.ornocar.com/general_disclaimer.html. -- You received this message because you are subscribed to the Google Groups "The 1962 to 1965 Mopar Mail List Clubhouse" group. http://groups.google.com/group/1962to1965mopars?hl=en. --- You received this message because you are subscribed to the Google Groups "The 1962 to 1965 Mopar Mail List Clubhouse" group. To unsubscribe from this group and stop receiving emails from it, send an email to 1962to1965mopars+unsubscribe@xxxxxxxxxxxxxxxxx For more options, visit https://groups.google.com/d/optout.