Posts like a Camaro
Join Date: Feb 2005
Location: Gilroy, California
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Heater core'* done, easier than expected.
Well, I swapped out the heater core yesterday on my '99 SLE. I was prepared for an all-day evolution, but the job only took about 3 1/2 hours.
I began by removing the hoses from the firewall side at the heater core, behind the shock tower. Bill Buttermore was kind enough to lend me his Mayhew clamp remover. After 15 minutes to so of maneuvering trying to get to the clamps, and failing, I got a long cold chisel out of my toolbox, and together with a dead-blow hammer, removed them in 2 minutes. (The nipples on the stock heater core are plastic. Coupla taps, they're off)
Now to the interior work. I read all the material on this site about removing the dash or going through the glovebox. Since I'm a big guy with a bad back, I decided removing the passenger seat was the way to go, and did so.
After removing the hush panel and looking around, I found that it was awkward to get to the two screws holding the heater core cover, but possible. I felt around on top of the box and removed the rod that moves the heater door It'* threaded, but fits into a snap-in fitting with no bolt on it. After then removing the small electrical plug that goes into the door motor, I used a 1/4" nut driver with a long extension on to get to the two screws. Took about 10 minutes. The heater core cover is a tight fit to remove from under the dash, but if you pull the carpet back, if will come out from the bottom.
Next, I grabbed the new heater core and greased the outside of the nipples with vaseline, removed the two screws holding the clamp on the old core, removed it, and put the new one in and tightened it down.
I bought new hoses from the dealer for this job ($22) and wouldn't do it without replacing the hoses, as it'* so hard to get to them. It was about a half-hour to get the hoses in place on the nipples (I vaselined the inside of the new hoses as well) and just used worm drive hose clamps because of the access problems. I was able to get down to the screw on the hoses once they were on with a long extension on a 1/4" ratchet.
Next, I hooked them up to the engine side (they are, almost unbelievably for GM, clearly marked) filled the cooling system for the coolant that leaked out, and started the car, letting it warm up to operating temperature to make sure there were no leaks. A check of both the interior, for a leaky core, and at the nipples, for watertight integrity, revealed that all was sealing perfectly.
Next, I reinstalled the heater core cover. Getting it carefully back into place, reinstalling the little electrical plug, and getting the motor'* pushrod back into place took about 20 minutes. I next checked for proper operation of heat, air, and defrost, and all was well.
Putting the seat back in was the work of a few minutes (I took the time to sweep out under it, there was 7 years worth of crud, there, of course) and next used leather conditioner on it while it was out.
The biggest waste of time was trying to go in through the dash. My '99 has a large, thick steel plate on the back of the glovebox, for some reason, and I couldn't get that removed, but as it turns out, it wasn't necessary.
Lastly, when I checked the box in which I had stored the new heater core and hose, I discovered the Mayhew clamp tool that Bill Buttermore mailed to me about 4 months ago. Man, was my face red-I'd forgotten all about it! It'* going out today, Bill, and thanks.
So, my advice to save time and money are:
1. I got the heater core on e-Bay. $22! The parts puppies wanted almost $70. It'* aftermarket, as well, and is all aluminum, not plastic, even the nipples.
2. Forget the glovebox, at least on a car without climate control, it'* not necessary to remove it.
3. Take out the passenger seat. Access under the dash is much easier.
4. Use new hoses. Also, don't waste time trying to get to the clamps at the firewall side of the old core. A long cold chisel or screwdrive works and saves tons of time.
Check for watertight integrity before reassemb;ing. You don't want to do this job twice.
I'll be happy to answer any questions others may have in this thread or by PM.
1999 SLE K engine