Little heat

[88silveradoRWD]

98 s-10 blazer 4.3, engine is operating at normal temp. about 190. Replaced thermostat, coolant full, no visible leaks, blower motor operates normal in all ranges. The temp. coming out vents is barely enough to dfrost windows, on highest temp. setting on dial. Does this sound like a plugged heater core, both inlet and outlet pipe from core seem about same temp. to touch. Is there anything i am missing, getting pretty chilly. Thanks for any info.

[Leeann94astro]

When engine is at operating temp, how hot are the heater hoses?

if they're not too hot to hold, I'd say you have a clogged core and need to backflush your core.

Also, have you burped the cooling system? You might have an air bubble.

[Chris Stewart]

You might try exercising the temperature knob a few times and verify cold temps to warm.
If flushing the heater core is necessary, start with gentle flow and pressure...we don't want to injure the heater core at all.
I don't know the procedure for burping the cooling system, please advise.
thanks

[Leeann94astro]

Put the passenger wheel up higher than the rest of the truck - on a ramp, jacked up with stands, whatever - and open the rad cap. Start the truck, run at ~1500 rpms or so, filling radiator as needed until truck has run at operating temp for a while (basically until it starts spitting). Turn off, let cool completely, do it again. It might take a few cycles if the heater core has air in it. These systems are more of a pain to bleed than most.

[blazes9395]

Lean94astro is right, the front has to be highest point of the coolant system to purge the air. On a level surface, the heater core is the highest part of the system. Any air will tend to find the highest point in the system. When you have a leak in the coolant system and you start hearing a sloshing sound inside the truck, its an indication air is getting into the cooling system.

It sounds like a common clogged, or partially clogged heater core to me. If they are both the same temperature, its most likely a partial clog. You have to back flush it. The two lines run from the firewall on the left side of the engine, on the top of the passenger side valve cover. Unhook both of these lines, and apply pressure(garden hose) to the smaller diameter hose. Keep working it until you have good flow through it out the other larger diameter hose. Like Chris said though, be carful not to over pressurize it or you will damage the heater core.

[ericn1300]

no need to lift the passenger side, just find a wide mouth juice container that fits snuggley inside the raditor fill tube. fill it with coolant and quickly insert it. the coolant in the jug will be the highest part of the cooling system and burp the air out.

[Chris Stewart]

Thanks for the info!

[88silveradoRWD]

Sounds good ill try to purge the air from system first since i had just put that thermostat in a few weeks before the problem started. Hope that works cuz my garden hose is put away for winter and its going to be a high of -10 up here in MN tomorrow. Thanks a lot i really appreciate it.