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73-87 Chevy _ GMC Trucks => Interior & Equipment => Heating, Ventilation & Air Conditioning (HVAC) => Topic started by: Customdeluxe81 on July 26, 2021, 10:30:18 am

Title: Thermostat and heater hose
Post by: Customdeluxe81 on July 26, 2021, 10:30:18 am

Can anyone tell me what thermostat my 1981 C10 with  250 6cylinder non ac takes? I’m thinking 180 but parts store says 195. Also does anyone know what size heater hose it takes? Is it 3/4 and 5/8 or something else ? Hoses are rough and I can’t find any markings on them.
Thanks
Bill

Title: Re: Thermostat and heater hose
Post by: Shifty on July 26, 2021, 10:44:56 am

The 195 is for emission laws, and most vehicles will run cleaner when warmer.  I prefer a 180 on most of my things, though I've run a 160 on a few.

Heater hoses are indeed 5/8 and 3/4. 

Title: Re: Thermostat and heater hose
Post by: bd on July 26, 2021, 10:53:51 am

195° F, 5/8", 3/4"

Title: Re: Thermostat and heater hose
Post by: Customdeluxe81 on July 26, 2021, 11:04:27 am

Thanks, that’s what I needed to know!

Title: Re: Thermostat and heater hose
Post by: Customdeluxe81 on July 26, 2021, 12:26:37 pm

Any thoughts on how to get more heat from this? New heater core? Do the aluminum heater cores put out more heat?

Title: Re: Thermostat and heater hose
Post by: bd on July 26, 2021, 01:03:51 pm

If the truck still has the original core, it is more than likely clogged to some degree.  Thorough flushing of the cooling system followed by a new 195° F thermostat, 50/50 antifreeze mix, and a new core should produce a significant improvement in heater function.