Heater Core Issue with 86 GN

kgturbo

New Member
Good Morning:
I was driving my GN yesterday when suddenly there was a slight antifreeze leak on my passenger side floor. I figure it has to be the heater core. But was wondering could it be a hose or hoses or any other part?? Should I replace the hoses and any other parts when dong this job, if it is the heater core? Is the heater core in the engine compartment or under the dash? I read that there are different heater cores and not only one that matches up with these beautiful cars. I also was wondering if someone could advise a step by step way of doing this job, if they have done it. Also how long should it take to do?

Thanks so very much!! Have a great Memorial Day Weekend and let us remember all of our Great Military people, past and present!!!!!
 

pacecarta

LOGGED OUT
Staff member
the hoses slip on the heater core far enough to leak into the box
check the core pipes at the ends of hose if they are dry , then you should be looking to replace the core or cap it off
if they are wet replace the hoses , try not to damage the core getting hoses off , and dont overtighten the clamps
kirbans and others like gbody parts sell hose kits for the heater
the core is inside the hvac box under the hood , you need to remove the lower windshield trim , the cowl screen , the trim brackets on firewall , the blower fan , the case bolts into firewall and then a bunch of 9/32 screws holding the case together (look down inside theres a couple more ) then pry the top of the box off
the only available replacement core i know of is an aluminum version thats a little smaller and needs some neoprene foam to seal up properly
you can also get a new gasket for the box from gbody parts and may need to use the top half to replace your old seal
also grab some 3m butyl strip caulk to reseal case top to the lower half and ultra black rtv to reseal the case to the firewall
 

GNRick

Retired member
the hoses slip on the heater core far enough to leak into the box
check the core pipes at the ends of hose if they are dry , then you should be looking to replace the core or cap it off
if they are wet replace the hoses , try not to damage the core getting hoses off , and dont overtighten the clamps
kirbans and others like gbody parts sell hose kits for the heater
the core is inside the hvac box under the hood , you need to remove the lower windshield trim , the cowl screen , the trim brackets on firewall , the blower fan , the case bolts into firewall and then a bunch of 9/32 screws holding the case together (look down inside theres a couple more ) then pry the top of the box off
the only available replacement core i know of is an aluminum version thats a little smaller and needs some neoprene foam to seal up properly
you can also get a new gasket for the box from gbody parts and may need to use the top half to replace your old seal
also grab some 3m butyl strip caulk to reseal case top to the lower half and ultra black rtv to reseal the case to the firewall
Only thing I can add is keep track of where the screws go. Some are different sizes. Also, for some reason, parts stores sometimes carry the wrong part for our cars. Match yours up with the one they order for you, if you don't get one from a Buick vendor.
 
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