I need to replace my heater core in a 1987 GMC Sierra 5.7 liter step by step as I am not that mechanically inclined From a female Thankyou

Heater core is under the dash in the same enclosure as the interior fan motor. as to remove/replace, I recommend getting a chilton's manual for your vehicle, they have step by step instructions and specifications. Its a great investment if you want to do things yourself, and if it's too complicated it should give you an idea as to what to expect from a mechanic

you left info for a 91 gmc sierra no such thing try again

pull blower out if no frash in there then replace the motor lower passenger side of the dash should be tree or four screws

ID BE LOOKING AT THE HEATER CORE FOR LEAKING. YOU MIGHT PRESSURE TEST IT FOR AN HR. YOU WILL MOST LIKELY FIND THE LEAK.:)

For 2000 GMC Truck Sierra 2500 4WD 5.3L SFI 8cyl the Fuel Filter is located: Under vehicle, driver side, below seating area, near fuel tank, mounted on frame rail in fuel line.



Fig. Typical in-line fuel filter mounting location

Hope this help (remember comment and rated this post).

There is no replacing of the inlet outlets on a heater core. You will have to replace the heater core.

no,, the system works from a vacuum and has to be worked on in a service garage. sorry about the bad news...

try autozone.com to see if they have your car listed for diagrams pictures and step by step instructions if your car is not listed then try your local library they have all the car manuals and even copy them for you and here is a place that sells only GM parts Schram auto and truck parts 1-800-292-1032 if you need it

Try “autozone.com” or your local library for diagrams and step by step instructions and for GM parts try Schram auto and truck parts 1-800-292-1032

I experienced the same head ache. First attempt was to replace the thrmostat and after taking it apart I realized that there was nothing wrong with it. I then removed the plastic cover/panel located under the dash board on the passenger's side. (only a few 4-5 smalls screws) Removal will enable you to see the on/off switch/gate moving/rotating as you turn the knob to hot or cold positions, on the control panel. If that switch/gate seems to work ok, then the trouble is within the heater core. Many mechanincs suggested that I replace the heater core. A very expensive proposition.
I checked the heater core supply/intake hose and found it hot to the touch, while the return hose was nearly cold. It was definitely a heater core blockage. I removed both ends (supply and return) hose connections/clamps. They are located near the fire wall in the engine compartment. A special tool is very helpful to remove those clamps easily and to replace them as well. It can be done the old fashion way but this tool was a life saver and reduced work time to just minutes. (Tool is $70.00 bucks at auto parts store,so I borrowed mine from a mechanic/friend)
I then hooked up a garden hose to the return end of the heater core and reversed the flow of coolant/water through the heater core. My truck is a Sierra 2000 and I refuse to see how a heater core could get clogged up with clear coolant alone. To my surprise a flat piece of rubber about the size of a quarter blew out of it and the flow of water became unobstructed. I reconected the ends of the hoses to the heater core, replaced the lost antifreeze & everything returned back to normal. No money spent for something most mechanics suggested I replace control valves/switches ($280.00) replace heater core ($500.00) etc etc. I am glad I was curageous enough to tackle this myself and save a few pennies. Good luck, and I hope this will work for you.