heater hose question
 

I have a 71 c10. it has a 2005 5.3 out of a Silverado.right now I have no a/c or heater.the installer blocked off the heater hose outlets. should they be blocked off or looped together?if looped together is the answer what size hose do I need?THANKS

Re: heater hose question
 

Better to run a bypass hose. I’m running one on my LS swap.
https://www.amazon.com/Heater-Bypass.../dp/B013QNJ9SQ

Re: heater hose question
 

THANKS I was not comfortable with capping them off.

Re: heater hose question
 

X2....I was told not to block them off if not running a heater...and to use a loop....

Re: heater hose question
 

Yes, they must be looped because the LS water pump, unlike the old small block chevy, does not have an internal bypass.

Re: heater hose question
 

THANKS everyone bypass hose is ordered. I ordered a extra for the guy who did the swap for me to show him the best way. this is only temporary till I can get the vintage air ordered.

Re: heater hose question
 

At which time you will go right back to blocking them off...... The way I understand it, which may or may not be right, is the system was designed the way it is for faster warm ups to help with emissions. Once the cooling system is full, it shouldn't matter. When you put a Vintage Air set up on it, whenever the A/C is on, the heater hoses will be blocked off by the heater control valve, essentially blocking the same ports off. I've personally put well over 200k miles on LS swapped vehicles with this same set up and never had an issue, most of which miles were put on in the heat of the summer with the aircon on.

Re: heater hose question
 

There is a big discussion regarding that on ls1tech, isn't there. Some guys put that pre-heater bypass loop in, others say its not necessary. I went your route. Leave it (without) until I see a need for it.

Re: heater hose question
 

Yes there is, those discussions get pretty heated at times. LOL! I've done it both ways and haven't seen a difference in either one.

Re: heater hose question
 

So if you are blocking them off what is the correct method? Is there a part that fits over the tube and then tightens like a hose clamp?

Re: heater hose question
 

mine has some rubber caps held on with hose clamps

Re: heater hose question
 

In can say with experience, you may overheat if you have a smaller radiator and the heater core lines are blocked. In my bmw 5 series LS swap, the heater core lines go to the factory heater valve. Maybe the same as vintage air system, ac on, no need for hot water to flow inside the ac box, and its closed. Ive seen the coolant temp rise above 220-230 before I realized what's going on (automerer gauge) That's at the water drilled and tapped next outlet by the tensioner. The temp sender in the head goes higher. As soon as the heater valve is opened, coolant temp goes down and back to normal. Before I thought the radiator was too small, stock. It wasn't the road, it was the design of the heater core flow. Also have the 160* stat
Clint

Re: heater hose question
 

Sounds to me like your main problem is the too small of radiator matched with a 160* thermostat. It's been my experience that putting too cool of a thermostat in actually does the opposite of what you would think by not letting the coolant to spend a sufficient amount of time in the radiator therefore causing it to actually run hotter.

Re: heater hose question
 

Never thought about it like that.. once I get the ac lines made up, I'll see how the temps are with the 160 stat and maybe change it to the 180 just to see.
Thanks for the help

Re: heater hose question
 

The LS runs better when it’s at or around 195, this allows the intake to better atomized the fuel so it’s runs more efficiently and economically.