Heater core

Tyrone, Check the attached links,instruction and guides, the last link has some very good info. and pics. on S10 heater core replacement. Good luck.
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Heater core replacement 2000 S10 4 3L slideshow picture
How to Change Heater Core on 1994 Chevy 10 Blazer GMC Jimmy Oldsmobile...
98 GMC Jimmy Heater Core Replacement Video Diary
Heater core replacement procedure 99 S10

Hi Ronald,

That vehicle is equipped with one of the easiest heater cores in the world to replace. Here are the instructions form the service manual:

Drain cooling system. Raise vehicle. From underneath, remove heater hoses from heater core. Remove drain tube. Lower vehicle. Remove right and left side sound insulator panels. Lower heating duct and hoses. Remove heater core cover and heater core. To install, reverse procedure. Fill and bleed cooling system.

HINT: I never drain the cooling system to replace a heater core. It is not necessary if you use a couple pairs of long-nose Vise-Grips to clamp off the heater hoses before you disconnect them from the heater core. That way, the only coolant you will lose is what is actually in the heater core itself.

sounds like a bad heater core usually located under the dash and stereo

Basic mechanical experience is all you need. Remove the intake tube, fan, fan shroud, upper and lower hoses and it comes right out. I think you can do the whole job with a 10mm wrench and a phillips screwdriver. (Maybe a couple other tools, but no special ones.) Be sure to get a 1" core radiator and not the stock 1/2" core, for added cooling capacity.

Check my tips and tricks in my profile. If you have a 88 ranger 4 cyl. like mine. It's a piece of cake. I can't imagine the 6 cyl version being that much more complicated but I haven't worked on one. If you have any mechanical skills and common screwdriver bits or small sockets it should take you all of 30 mins. And like everything else I ever had to replace on the truck it costs $25 - $35.