67 Skylark Heater Core Replacement

[jedbmw]

What is the straight scoop on replacing the heater core in my 67 Sklark. No air.

I have heard about the hole drilling in the fender well and I have heard that to just take the damm fender off.

can anyone give me the straight scoop.  If I drill the hole how do mI reseal the outer housing?

I just want to do it correctly.

Any info would be appreciated.

[rocketraider]

Do you have the factory service manual for your car? It will outline the whole process.

 

Cutting out the flap stamped into the inner fender is a shortcut for some years Olds blower removal/replacement. Not sure on Buick A-body. If you cut the hole save the plug, but you might have to use a larger diameter plate to cover it. Seal it with small sheetmetal screws, then with rtv or body seam sealer if you can get that.

 

On a job like this, I tend to look at what is going to make the job go easiest and simplest. If that means drop the inner fender, do it.

[joe_padavano]

All 1964-67 GM A-body cars have exactly the same firewall and HVAC boxes. The only differences are A/C vs. non-A/C. The heater core itself is in the box under the dash. The problem is that common fasteners run all the way through the firewall and retain both the under-dash box and the box on the engine side of the firewall. There is one fastener that is on the lower outside corner of the firewall-side box. This fastener must be removed to release the under-dash box from the firewall. The only non-destructive way to do this is to pull the fender, or at least the inner fender. The problem with doing that is that the clip nuts that the fender fasteners thread into are almost always rusted and will snap off and just spin when you try to remove the bolts. In nearly 50 years of working on these cars, I have NEVER been able to remove all of them without damage. This invariably means taking the fender off to fix it right, which also means taking the hood off first. Don't be surprised when you find rot in the fender.

 

This is why some people advocate just cutting a hole in the inner fender. Personally I can't bring myself to cut unnecessary holes in perfectly good factory parts, but that's your call. I will say that once you get the inner fender out of the way, replace the blower motor at the same time. If you don't, you'll find that Murphy was an optimist.

[jedbmw]

So I just completed the job. The nut that everyone says is Impossible to get at was tight but far from difficult.  The one tight fastener located on the lower left of the heater box in the engine compartment required some patience but it was accessible. I was able to get at it from the engine compartment and no I did not put it back on. Hard to believe that the factory service manual wants you to cut the inner wheel well. 
Header bolts are in tighter places. Job took less than an hour. 

[rocketraider]

Dealer mechanics get paid according to flat rate manual. If a factory time study said job can be done in x amount of time using this procedure e.g. cut a hole in the fenderwell vs fumbling after that fastener for an hour, that's the time they got paid for.

 

Two fallacies: 1) engineering and design sometimes make the job more complicated than needed, 2) flat rate manuals assume perfect conditions. As in no rusted fasteners, no 50 yr buildup of grunge, you get the idea.

[joe_padavano]

1 hour ago, jedbmw said:

So I just completed the job. The nut that everyone says is Impossible to get at was tight but far from difficult.  The one tight fastener located on the lower left of the heater box in the engine compartment required some patience but it was accessible. I was able to get at it from the engine compartment and no I did not put it back on. Hard to believe that the factory service manual wants you to cut the inner wheel well. 
Header bolts are in tighter places. Job took less than an hour. 

 

My hat's off to you. I've never had any luck. Maybe the contours of the Buick fenders are just different enough from Oldsmobile to let your hand in.