Heat issue 4.3 s10

[4x4ZR2]

I have a 2000 s10 with the 4.3. The heat Works ok (not great) while driving or revving engine but cools off when at idle. I checked the coolant and it was low so I topped it off. That seemed to help a little bit but not that much. Engine usually warms up to 160 when it's not 0 degrees outside. Doesn't smell like coolant inside the truck and I don't have any noticeable leaks anywhere. I can feel a difference in the temp by adjusting the temp knob in the truck.  The problem started about a week or so ago. Any ideas? Thanks

[Crazymays77]

they are know for clogging in the heater core. try to back flush it and see if that helps. here about this all the time. i bet that is the issue.

[4x4ZR2]

How would I go about doing that? Never done it before

[Crazymays77]

Pull the heater hoses off and take a garden hose and run water thru it backwards. Top hose should be the outlet so that's the one u will want to put the garden hose on. What u could do before this is go for a drive then check both heater hoses and see if there is a diff in temp between them.

[4x4ZR2]

That's pretty much what I just read on google. Will give it a shot tomorrow. Thanks

[Crazymays77]

No prob

[BIG TODD]

dump white vinegar in it instead of water had to do it on my jimmy every winter

[burl]

Dont use a hose go to the car wash n take both hoses off the heatercore, spray big side first till clear the little side till clear that way u wont get much of a bubble or barly any coolant lost, just did it to my new truck and had to do it to my blazer in the fall

[J.C.]

I wouldnt use high pressure on it...

[jbexc]

My zr2 did the same thing,new thermostat fixed it.

[72 Bogger]

Sounds like a stuck open thermostate to me. It ain't got enough pressure to build heat. And as jc stated DON'T use a power washer to flush the heater core.

[4x4xdodgeman]

I say put thermostate, it sould run at 195*

[4x4ZR2]

i changed the t-stat not too long ago so thats why i wasnt thinking that was it. but there only $5 or so so ill throw a new on in.

[71 Highboy]

I wouldnt use high pressure on it...

x2 garden hose works fine. ive done it on several vehichles. i flush them both ways?

[burl]

Car wash power washer is fine, ive done it many times garden hose doesnt have enough pressure to get everything out, used a garden hose 3 times in a row, id have heat for a day (thats after completly flushing the system n new coolant) I finally said screw it n went to the car wash and now it will cook you outta it

[burl]

And its not the t stat, argued with the guy for an hour who I bought it from, stopped at the car wash on my way home n wah la I had heat

[Mudgrunt]

had the same issue with my sons Zr2 changed t-stat no difference pulled hoses of heater core flushed out with garden hose works great very simple fix

[4x4ZR2]

what about compressed air? my spigot is frozen out side

[4x4ZR2]

blew out the heater core with air, poored some water in and blew that threw both sides. little improvement. going to get a t-stat. engine wont heat up over 120 even while being hard on it so hopefully thats the issue

[burl]

Still a clogged heater core, seriously take it to the carwash it will not hurt it