[Help]'73 Possible Heater Core/Cooling System Issue
Thread Starter
Team Owner
Joined: Apr 2002
Posts: 26,563
Likes: 29
From: Northridge California
St. Jude Donor '14
[Help]'73 Possible Heater Core/Cooling System Issue
'73 L82 with stocker cooling system...I bought this car a few weeks ago.
Car had a Moroso 27-29lbs 'Racing Use Only' Radiator cap on it. Car has been running fine with that cap, no overheating or issues etc.
Decided to swap for a correct 15psi cap. Drove the car around a bit. First thing I noticed about 10 minutes into the drive, was a coolant smell. Then I noticed some smoke/steam coming out of the heater vents. The car never overheated. Pulled into the garage and noticed coolant on the PASSENGER side floor mat. So...
Heater Core? What other possibilities could be going on here?
Car had a Moroso 27-29lbs 'Racing Use Only' Radiator cap on it. Car has been running fine with that cap, no overheating or issues etc.
Decided to swap for a correct 15psi cap. Drove the car around a bit. First thing I noticed about 10 minutes into the drive, was a coolant smell. Then I noticed some smoke/steam coming out of the heater vents. The car never overheated. Pulled into the garage and noticed coolant on the PASSENGER side floor mat. So...
Heater Core? What other possibilities could be going on here?
Last edited by Chinaski; Sep 20, 2012 at 10:04 PM.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
It does seem odd that after lowering the system pressure (27-29# down to 15#) you all of a sudden develop a leak in the heater core, but that is exactly what it appears you have, a leak in the heater core. Unfortunately not at all uncommon for a vintage C3, especially if it's the original one. I would check out the hoses and fittings under the hood where they go through the firewall, just to eliminate them as a possible source of a leak (possible, but not probable however).
If you do end up changing out the heater core, do get the best one available, not the least expensive one. Changing out the heater core is not a job you want to do very often at all.
Wait, you did say on the "drivers side floor mat"... didn't you? Did you mean to say the passenger (right) side? Does the car have air conditioning?
Good luck... GUSTO
If you do end up changing out the heater core, do get the best one available, not the least expensive one. Changing out the heater core is not a job you want to do very often at all.
Wait, you did say on the "drivers side floor mat"... didn't you? Did you mean to say the passenger (right) side? Does the car have air conditioning?
Good luck... GUSTO
Thread Starter
Team Owner
Joined: Apr 2002
Posts: 26,563
Likes: 29
From: Northridge California
St. Jude Donor '14
It does seem odd that after lowering the system pressure (27-29# down to 15#) you all of a sudden develop a leak in the heater core, but that is exactly what it appears you have, a leak in the heater core. Unfortunately not at all uncommon for a vintage C3, especially if it's the original one. I would check out the hoses and fittings under the hood where they go through the firewall, just to eliminate them as a possible source of a leak (possible, but not probable however).
If you do end up changing out the heater core, do get the best one available, not the least expensive one. Changing out the heater core is not a job you want to do very often at all.
Wait, you did say on the "drivers side floor mat"... didn't you? Did you mean to say the passenger (right) side? Does the car have air conditioning?
Good luck... GUSTO
If you do end up changing out the heater core, do get the best one available, not the least expensive one. Changing out the heater core is not a job you want to do very often at all.
Wait, you did say on the "drivers side floor mat"... didn't you? Did you mean to say the passenger (right) side? Does the car have air conditioning?
Good luck... GUSTO
Passenger side, my fault. I'm going to bypass it for now, it's a fair weather car anyway.
Any tips for bypassing it? I can use the search function, but figure since I'm here I'll ask.
Burning Brakes
Joined: Sep 2012
Posts: 818
Likes: 0
From: coon rapids mn
remove the two smaller coolant hoses going to the fire wall .you can use a brass fitting to connect them together .or you can eliminate the heater hoses and their fittings with threaded plugs on the water pump and the intake .inspect your radiator to make sure it won't leak also.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
Since you're dealing with two different sized hoses, I found a fitting that is 3/4" on one end and 5/8" on the other and just removed the hoses from the heater core and connected them together with the fitting. I also capped the heater core outlets to keep any insects from building nests in places you don't want them.
Good luck... GUSTO
Thread Starter
Team Owner
Joined: Apr 2002
Posts: 26,563
Likes: 29
From: Northridge California
St. Jude Donor '14
Thanks to all, I bypassed the Heater Core today. I used two 1/2 inch NPT Brass Pipe Plugs on the water pump and intake. Hoses removed from the car. Ran the car for a few minutes and drove it around the block and everything seems okay. I'll drive it a bit more tomorrow to make sure.
I'm in SOCAL, so not having a heater isn't the end of the world. This is strictly a fair weather car anyway. I'll get around to fixing the heater core eventually, but a minor priority right now for me.
I'm in SOCAL, so not having a heater isn't the end of the world. This is strictly a fair weather car anyway. I'll get around to fixing the heater core eventually, but a minor priority right now for me.
