Heater Core took a dump. Is changing it really that Bad?
09-03-2010, 10:53 PM
#1
Racer
Thread Starter
Heater Core took a dump. Is changing it really that Bad?
For a number of month's now, I've suspected my heater core was on its way out. What started off as just an occasional smell of anti-freeze from time to time, gradually turned into having "steam" pouring out of my dash vent and fogging up my windshield every time the car started, or came to a complete stop. :o
I'd been putting off replacing the heater core for the longest time due in no small part, to all the horror stories I'd read on this forum in regards to removing them.
Last week, while vacuuming my car, I discovered my passenger-side floor mat completely soaked with anti-freeze and accepted the fact that the heater core had finally took a dump. I couldn't put it off any longer. The core had to be replaced...
I didn't bother to look through a repair manual because they usually only make things look a lot harder then they really are. It's always been my experience that common sense, patience and a good set of tools are usually all I've ever needed when working on cars. Just pay attention and make note of how things are while you're removing them so that you know how to re-install everything back to the way it was. I've only ever used manuals when I need specific information like torquing specs...
The following is a small write-up of how I went about replacing the heater core. Generally, I take a lot picture when I work on my car but due to the really cramped work area and the fact that there'd nothing much behind the dash besides a rats nest of wiring and darkness, I couldn't really take many photo's but I hope the photo's I did take, will be enough to help anyone looking to tackle this job on their 'Vette...
I started off loosening the 2 screws and 2 bolts holding the surge tank in place. Then I carefully moved it over so I had access to the 2 heater hoses underneath leading to the heater core through the firewall.
The hoses were caked on pretty bad, so I had to slice them down the side about 3/4" with an X-acto knife in order to pull them off.
Because there was still some antifreeze in the lines, I made sure I slid a tray underneath the car to catch any if it spilled. With the 2 lines pulled out, I simply wedged them off to the side pointing upwards so no more coolant would spill out of them.
(Though the picture doesn't show it because I took it later on, the heater core ends stick out about 1" from the firewall)
Now that all the outside work was done, I made my way inside of the car...
I removed the 2 screws holding the hush panel into place, then gently disconnected the wire that runs to the small light that's attached to panel. I squeezed my head into the foot well and peered into the dark void behind my dash. This was definitely NOT going to be a walk in the park....
Aside from being darker than ape sh*t in there, it was cramped, hot and there was about a million wires all over the place making access to the heater core and housing screws all the more difficult.
***I suppose if I could give anyone looking to tackle this job just one piece of advice, it would be this***
DO YOURSELF A FAVOR AND REMOVE THE PASSENGER SEAT!!!
I didn't because I'm a moron and like making things difficult for myself. By the time this little project was over, I had twisted and contorted myself into positions I never knew the human body was capable of.
(Just to give you an idea how cramped and uncomfortable it is in there with the seat still in place, go out and open your passenger side door and look inside. Not very much space in that foot well is there?)
Now imagine having to stick your head way up in that foot well so that the top of your head is right up against the fire wall. Now picture your lower back/@ss arched up and leaning off the very edge of the seat and your legs/feet sticking out the roof-line. This is NOT a natural position for the human body to be in.
Do yourself a favor and learn from my mistake. Take out the darn seat!! It will make a world of difference.
Once I'd finally positioned myself in there, 3 of the bottom screws were immediately visible and relatively accessible. I used a 1/4" wrench and socket with a flexible extension to get at the screws. I believe they were 9/32". You also have to unhook a bunch of clips GM decided to use to hold a bunch of wiring to the plastic shell that covers the heater core. They all have to come out before you can pull off the cover.
Next, I took out the glove box lid. I was really hoping I'd have access to the top screws this way, as I didn't want to remove the entire dash like most others have had to do.
There are 6 screws holding the hinge/door in place. Remove them and carefully pull away the door and set it aside.
Next you will find two philips screws holding the latch in place. They also happen to hold the entire tray in place as well.
Remove them and pull out the tray.
Right away I saw that at least one of the top screws was visible and accessible using a wobble extension. Good stuff. 4 screws down, one to go.
The 5th and final perimeter screw is way in the back on the right side just below the windshield. I was totally blind on this one, but after finding it with my fingertips, I used a 1/4" wrench with an adjustable extension and amazingly enough, found the head of the screw the first time in. So far, things were going pretty darn good...
Before the cover can be pulled out, there are 3 small plastic hose's that direct air to the various vents behind the dash that need to be disconnected. They just pull right out and can be slid back into place later.
Unfortunately, as I found out later, not only are there the 5 perimeter bolts to remove, but there's a hard plastic hose screwed into the middle of the plastic cover with two screws holding it in place.
You can see in the picture below the hole in the cover. That's where the hose goes into. Just above and below it, are two screws holding it in place.
The bottom one, I got from underneath. The top one was a MAJOR pain in the butt and probably added about 1.5 hours to the job.
This one single screw was a real head ache, but eventually, I was able to get the little b@stard out!
With that out of the way, I now had the joy of trying to pull out the cover through the foot well. A job easier said than done. All the wiring back there is in the way so I had to take my time and move the wiring around as I pulled out the cover .
With that done, I finally had access to the heater core. You'll notice right away there a thin metal "strap" along the bottom of the core with a screw on one end of it. This little arm/strap basically just holds the heater core in place. Remove the screw and swing out the arm and pull out the core.
There will still be some anti-freeze inside, so if your floor isn't already soaked like mine was, you may want to put a plastic bag on the floor so your carpet wont get wet.
Looking at the old core, it was obvious it was leaking from the top corner...
I could also see that a few of the rows of "fins" were bent/crushed for whatever reason. It was probably put in that way 18 years ago from the factory so I guess I can't really complain since its lasted this long...
Before I installed the new one, I made sure the new core matched the old...
Then went about putting everything back together.
I noticed afterwords while trying to install the new core, that there was another little bracket at the top of the inner housing which I'm assuming was there to hold the heater core into place just like the little arm/strap at the bottom.
As hard as I tried, I was not able to slide the new core back into place with this "hold-down" bracket in place. I decided just to remove it. With that out of the way. The core went right in. I tried to re-install the upper bracket but couldn't. I couldn't see it and couldn't even reach it if I did.
I ended up leaving it off since there's really no need for it. The core is held in place by the bottom strap and the inlet/outlet pipes extending out of the firewall towards the engine also keep the core in place. Then there's the plastic front cover which also helps keep the core in place as well. Bottom line is, that upper bracket is totally over kill and NOT necessary. Good riddance.
Once the core was put back in, I started up the car and let it idle to reach normal operating temperature. Turned on the heater and inspected the outside lines as well as the core itself, for any leaks.
All was well.
Put the plastic cover back on (another major pain in the butt with all those wires in the way) re-attached the 3 plastic vent-hoses on the inside and once again started the car. I cycled through each of the vent settings to make sure all the vents were working the way they were supposed to.
Again, all was well and each "mode" worked as it should. I finally re-attached the glove box liner and installed the door again.
Note:
The top right screw just below the windshield (the one totally hidden away, unfortunately, I was not able to put back but there doesn't appear to be any sealing issues with the box as I did not feel any leaks from that area even with the heater on full blast. The 4 remaining screws hold the two haves of the box together tight enough and there's a "ridge" between the two haves that basically locks them into place when the perimeter screws are tightened. No air leaks, no problem. Haven't given it a second thought since.
The whole job probably took me about 5-6 hours but I know I could have done it in less time had I removed the seat and been allowed to work a little more comfortably but hey, live and learn I guess.
My heater is now working again, no more anti-freeze smell, no more fogged up windshield, I can go back to enjoying the car again.
In a nut shell, yes, it's a time consuming project. Patience is definitely a MUST and thin arms really go along way in helping you reach some of the screws but this project IS doable in a garage with some basic hand-tools in an afternoon. Any reports of HAVING to remove the entire dash are not entirely true. I didn't, and everything turned out alright!
Just remember, take your time, be patient and don't forget to remove the seat.
I'd been putting off replacing the heater core for the longest time due in no small part, to all the horror stories I'd read on this forum in regards to removing them.
Last week, while vacuuming my car, I discovered my passenger-side floor mat completely soaked with anti-freeze and accepted the fact that the heater core had finally took a dump. I couldn't put it off any longer. The core had to be replaced...
I didn't bother to look through a repair manual because they usually only make things look a lot harder then they really are. It's always been my experience that common sense, patience and a good set of tools are usually all I've ever needed when working on cars. Just pay attention and make note of how things are while you're removing them so that you know how to re-install everything back to the way it was. I've only ever used manuals when I need specific information like torquing specs...
The following is a small write-up of how I went about replacing the heater core. Generally, I take a lot picture when I work on my car but due to the really cramped work area and the fact that there'd nothing much behind the dash besides a rats nest of wiring and darkness, I couldn't really take many photo's but I hope the photo's I did take, will be enough to help anyone looking to tackle this job on their 'Vette...
I started off loosening the 2 screws and 2 bolts holding the surge tank in place. Then I carefully moved it over so I had access to the 2 heater hoses underneath leading to the heater core through the firewall.
The hoses were caked on pretty bad, so I had to slice them down the side about 3/4" with an X-acto knife in order to pull them off.
Because there was still some antifreeze in the lines, I made sure I slid a tray underneath the car to catch any if it spilled. With the 2 lines pulled out, I simply wedged them off to the side pointing upwards so no more coolant would spill out of them.
(Though the picture doesn't show it because I took it later on, the heater core ends stick out about 1" from the firewall)
Now that all the outside work was done, I made my way inside of the car...
I removed the 2 screws holding the hush panel into place, then gently disconnected the wire that runs to the small light that's attached to panel. I squeezed my head into the foot well and peered into the dark void behind my dash. This was definitely NOT going to be a walk in the park....
Aside from being darker than ape sh*t in there, it was cramped, hot and there was about a million wires all over the place making access to the heater core and housing screws all the more difficult.
***I suppose if I could give anyone looking to tackle this job just one piece of advice, it would be this***
DO YOURSELF A FAVOR AND REMOVE THE PASSENGER SEAT!!!
I didn't because I'm a moron and like making things difficult for myself. By the time this little project was over, I had twisted and contorted myself into positions I never knew the human body was capable of.
(Just to give you an idea how cramped and uncomfortable it is in there with the seat still in place, go out and open your passenger side door and look inside. Not very much space in that foot well is there?)
Now imagine having to stick your head way up in that foot well so that the top of your head is right up against the fire wall. Now picture your lower back/@ss arched up and leaning off the very edge of the seat and your legs/feet sticking out the roof-line. This is NOT a natural position for the human body to be in.
Do yourself a favor and learn from my mistake. Take out the darn seat!! It will make a world of difference.
Once I'd finally positioned myself in there, 3 of the bottom screws were immediately visible and relatively accessible. I used a 1/4" wrench and socket with a flexible extension to get at the screws. I believe they were 9/32". You also have to unhook a bunch of clips GM decided to use to hold a bunch of wiring to the plastic shell that covers the heater core. They all have to come out before you can pull off the cover.
Next, I took out the glove box lid. I was really hoping I'd have access to the top screws this way, as I didn't want to remove the entire dash like most others have had to do.
There are 6 screws holding the hinge/door in place. Remove them and carefully pull away the door and set it aside.
Next you will find two philips screws holding the latch in place. They also happen to hold the entire tray in place as well.
Remove them and pull out the tray.
Right away I saw that at least one of the top screws was visible and accessible using a wobble extension. Good stuff. 4 screws down, one to go.
The 5th and final perimeter screw is way in the back on the right side just below the windshield. I was totally blind on this one, but after finding it with my fingertips, I used a 1/4" wrench with an adjustable extension and amazingly enough, found the head of the screw the first time in. So far, things were going pretty darn good...
Before the cover can be pulled out, there are 3 small plastic hose's that direct air to the various vents behind the dash that need to be disconnected. They just pull right out and can be slid back into place later.
Unfortunately, as I found out later, not only are there the 5 perimeter bolts to remove, but there's a hard plastic hose screwed into the middle of the plastic cover with two screws holding it in place.
You can see in the picture below the hole in the cover. That's where the hose goes into. Just above and below it, are two screws holding it in place.
The bottom one, I got from underneath. The top one was a MAJOR pain in the butt and probably added about 1.5 hours to the job.
This one single screw was a real head ache, but eventually, I was able to get the little b@stard out!
With that out of the way, I now had the joy of trying to pull out the cover through the foot well. A job easier said than done. All the wiring back there is in the way so I had to take my time and move the wiring around as I pulled out the cover .
With that done, I finally had access to the heater core. You'll notice right away there a thin metal "strap" along the bottom of the core with a screw on one end of it. This little arm/strap basically just holds the heater core in place. Remove the screw and swing out the arm and pull out the core.
There will still be some anti-freeze inside, so if your floor isn't already soaked like mine was, you may want to put a plastic bag on the floor so your carpet wont get wet.
Looking at the old core, it was obvious it was leaking from the top corner...
I could also see that a few of the rows of "fins" were bent/crushed for whatever reason. It was probably put in that way 18 years ago from the factory so I guess I can't really complain since its lasted this long...
Before I installed the new one, I made sure the new core matched the old...
Then went about putting everything back together.
I noticed afterwords while trying to install the new core, that there was another little bracket at the top of the inner housing which I'm assuming was there to hold the heater core into place just like the little arm/strap at the bottom.
As hard as I tried, I was not able to slide the new core back into place with this "hold-down" bracket in place. I decided just to remove it. With that out of the way. The core went right in. I tried to re-install the upper bracket but couldn't. I couldn't see it and couldn't even reach it if I did.
I ended up leaving it off since there's really no need for it. The core is held in place by the bottom strap and the inlet/outlet pipes extending out of the firewall towards the engine also keep the core in place. Then there's the plastic front cover which also helps keep the core in place as well. Bottom line is, that upper bracket is totally over kill and NOT necessary. Good riddance.
Once the core was put back in, I started up the car and let it idle to reach normal operating temperature. Turned on the heater and inspected the outside lines as well as the core itself, for any leaks.
All was well.
Put the plastic cover back on (another major pain in the butt with all those wires in the way) re-attached the 3 plastic vent-hoses on the inside and once again started the car. I cycled through each of the vent settings to make sure all the vents were working the way they were supposed to.
Again, all was well and each "mode" worked as it should. I finally re-attached the glove box liner and installed the door again.
Note:
The top right screw just below the windshield (the one totally hidden away, unfortunately, I was not able to put back but there doesn't appear to be any sealing issues with the box as I did not feel any leaks from that area even with the heater on full blast. The 4 remaining screws hold the two haves of the box together tight enough and there's a "ridge" between the two haves that basically locks them into place when the perimeter screws are tightened. No air leaks, no problem. Haven't given it a second thought since.
The whole job probably took me about 5-6 hours but I know I could have done it in less time had I removed the seat and been allowed to work a little more comfortably but hey, live and learn I guess.
My heater is now working again, no more anti-freeze smell, no more fogged up windshield, I can go back to enjoying the car again.
In a nut shell, yes, it's a time consuming project. Patience is definitely a MUST and thin arms really go along way in helping you reach some of the screws but this project IS doable in a garage with some basic hand-tools in an afternoon. Any reports of HAVING to remove the entire dash are not entirely true. I didn't, and everything turned out alright!
Just remember, take your time, be patient and don't forget to remove the seat.
Last edited by LT1*C4; 12-21-2010 at 06:06 PM.
09-03-2010, 11:47 PM
#2
Heel & Toe
Member Since: Jun 2010
Location: Alabama
Posts: 17
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Congrats! You have now discovered what a true joy it is to own and maintain a corvette. I maintain that nobody has had fun with their corvette until they have replaced the heater core. Did mine about two months back. Unfortunately in a '94 there is no glove box, just a crappy air bag. Dash removal is a necessity to get the bag out of the way. I've heard rumors that it can still be accomplished with out doing it, but if there was, I couldn't find it. Damn near wasn't able to get the box open even with access from the top. If it starts leaking again, I'm gonna sell! 
You have now discovered what a true joy it is to own and maintain a corvette. I maintain that nobody has had fun with their corvette until they have replaced the heater core. Did mine about two months back. Unfortunately in a '94 there is no glove box, just a crappy air bag. Dash removal is a necessity to get the bag out of the way. I've heard rumors that it can still be accomplished with out doing it, but if there was, I couldn't find it. Damn near wasn't able to get the box open even with access from the top. If it starts leaking again, I'm gonna sell!
09-04-2010, 09:34 AM
#5
Drifting
What a great write-up man, way to document it! You should have Socal put it in the DIY section.
And yes, now was the best time to do it.
And yes, now was the best time to do it.
