I NEED TO REPLACE MY HEATER CORE

1991 Isuzu Stylus

Tiny

Siam

November, 16, 2011 AT 1:10 AM

I have no idea being a woman where the heater core is for this car. I plan to do the job myself but I was hoping for a diagram or instructions on how to do this? Anyone with ideas?

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4 Answers

Tiny

DrCranknWrench

November, 16, 2011 AT 1:20 AM

I have attached instructions and diagram, Referred to as FIG 8 in instructions.

Tiny

Siam

November, 16, 2011 AT 3:06 AM

Thank you so much but can you tell me is it under dash or on motor side?

Tiny

Siam

November, 16, 2011 AT 3:09 AM

Can you get a lil more info on this like does the whole dash have to come out if its there?

Tiny

DrCranknWrench

November, 16, 2011 AT 4:32 AM

You will mainly be working under the dash. The only work in the engine bay is to remove the 2 hoses which are the inlet/outlet hoses. There is usually a nut or 2 that hold the heater core in place and are removed from the engine bay on the firewal and will be right next to hoses.
Under the dash in the middle, you will find the heater box which is the diagram I sent you. You may have to remove some things to get them out of the way, but it is pretty straight forward and you can usually remove the whole box and pull it out and put the heater core in with it out of the vehicale. Then you just put the whole assembly back in and all you do is line up the hose inlet/outlet on the heater core to the holes in the firewal, this is where the hoses connect, and then bolt the box in and hook up hoses and retaining nuts and you are done.
When you refill the sytem with anti-freeze turn the heat all the way up, temperature, so that theheater core will have full flow and after you fill the radiator, start the vehicle and continue to fill it until it reaches operating temperature or when the level drops, this is the thermostat opening. Drive it around some, but don't go on a road trip yet, let it cool off until you can safely remove the radiator cap and repeat the process.
This is the best way to keep air bubbles from formaing in the sytem. Sometimes it still happens. Some vehicles have a bleed screw on the thermostat housing. You would open this until it just started to move and then with the car running to do aforementioned, put the raiator cap on and when it gets to operating temp, open it and let it flow some, close it. Repeat until the flow comes out in a steady stream. Then you should be good to go, but just keep an eye on it the first 100 miles or so. When you empty or nearly empty the cooling sytem it can be a bear to keep air bubbles out which will cause overheating.
So, watch temp gauge and keep anti-freeze with you in vehicle for a while so you don't get stuck. Just in case.

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