Heater Core


New Member
Dec 1, 2005
Has anyone ever had to replace a heater core in a 87 Buick Grand National? Just wandering because i need to do it pretty soon and i was just wanding what kind of a job i was getting into.
It's not entirely too hard. Its located on the passenger side. Just have to take off the windshield wiper and the cover it rests on. Its pretty striaghtforward...maybe an hour or two.
Ive done all three of my 85 turbo Buicks, and I dont believe there is any difference between the 85's and the 87's. Although it takes a while to do it its not hard and can be done in a few hours as long as your patient.

Heres step by step instructions

Completely remove both wiper arms. Take off the metal trim that goes along the bottom edge of the window, there are 4 screws that hold this on. Remove the cowl seal. Take off the vent screen that covers your airbox inlet, there are I believe 4-5 screws that hold it in place and two of these are holding your passenger side windshield washer sprayer on. Now look at the firewall and right under where the winshield trim sits and above the air intake for the air box there will be two metal brackets that you have to remove. There is a heatshield that mounts with one screw to the side of the lid on the 84/85 but Im not sure if the 87s have these. After those are off you can start taking out all the screws that hold on the air box lid. Just carefully check to make sure you dont miss any. There are two screws located down inside the air box inlet. Also there are 4 largers bolts that hold the lid to the fire wall. I usually remove the blower motor and all the other sensors/conectors and such from the lid as well just to get everything out of the way. Once everything is clear and you make sure you have all the little screws out of the lid just carefully start pulling up on it and it should come right off may take a little prying. If it doesnt come easily though youve missed a screw. Once the lids off you will see the heater core which is held in place by one screw that is right between the two tubes coming out of it. When you remove this screw make sure you note which way the little bracket that holds it in place is sitting. Remove the two heater lines from it and pull it out. Reverse the process to install the new one. When it comes to putting the lid back on it will take some coaxing to get it back down into place but just be patient about it and make sure you put new 3M rope seal all the way around the base to make sure your air box doesnt leak. If you have any questions just email me and Ill help you out. dthom8787@yahoo.com
3 hours your first time.

Under 2 the second time.

Don't forget to seal it up good. :)

gnttype.org has a tech hint topic for it I believe.
To save you doing it a second time- have the necks ( where the tubes enter the core) on the new heater core soldered all around each one where it goes into the core- makes the necks about 5 times stronger for when you remove your hoses- it wont loosen up the tubes coming out of the heater core where most leaks originate. 84/85s are different from 86/87s-the tubes come out at different angles.