Salerno's Auto Air

Sometimes it takes a little help from a professional. I took Helen over to Salerno's Auto Air and showed them my problem. Terry pointed out that the thin tube would overheat and melt before the thick block it was attached to would let the braising material melt to seal the crack. He figured it was better to get a replacement part. I left the car with him all day and he found one replacement part, put fresh hose on it, charged the system and found no other leaks. I think we're back in business. :D Blows nice and cold again.

A/C Leak

No luck on the A/C leak. It seems there is a second problem that is due to a tiny crack where the aluminum tube is brazed onto the block that attaches at the back of the compressor. Wow, no chance of getting a replacement any time soon. I guess I will have to break down and take the car over to a shop that can repair the crack. It would be so nice to have a spare to drop off and have refreshed with barrier hose, but I can't drive tha car in this heat anyway. Phooey!

A/C

Well, it may not be the o-rings on the compressor that are leaking after all. When the car was converted to use 134a, the kit they used had a high pressure adapter that has a 90° swivel bend in it. I was checking to see if it was loose and it turns out it was. I started to tighten it down but then though I'd better check the o-ring in it... voila! The o-ring is toast.
Closer inspection reveals that this o-ring is even more critical than usual on an adapter. The adapters I've seen are straight and very short. They do not have their own schrader valve but rely on the original R-12 valve. The o-ring in these adapters is only to seal when charging the system. As soon as the hose set is removed from the adapter, the original core seals shut and the o-ring does nothing, essentially. But because this adapter has the bend, the original core was removed and there is a schrader valve in the adapter instead. The o-ring now has to hold pressure all of the time, not just when charging. And with the swivel, it has to be a perfect seal or it leaks like crazy. Copper flare-nut type swivels, which this is similar to, can be really tightened down to seal and the soft copper will crimp itself to the shape needed to seal as you go tighter. But you can only tighten this swivel down so far before the o-ring distorts and tears... exactly what happened.

Off to Pep Boys for a replacement high side adapter... of course they only had the pair in a full conversion kit. No matter, it included a new schrader valve core, which I was going to need as mine had been removed. The bend in the old adapter had made it easier to connect the charging hose, but I found that it wasn't much more trouble to connect with the straight stubby one though. The seal will be so much more reliable it will be well worth any minor inconvenience anyway.

Right now I have a 15 in vacuum pulled on the system and I'm waiting to see if it holds. I had already ordered an assortment of o-rings and if the system won't hold the vacuum I'll need to wait for them to arrive before I can charge. But I think these o-rings are OK. For one thing, the compressor is a rebuilt unit and the rings are green, so they are correct for 134a. They can't be that old!

Thermal Vac Switches

Replaced the two thermal vacuum port switches that manage all the smog control devices. I seem to have them back to working in harmony again now.

Unfortunately, when I charged up the A/C system I found that the compressor is leaking at the back where the hose pad connects. Probably just the o-rings but now I need to find a set that work with 134a.

More EGR Investigation

After following the troubleshooting steps in the manual, I see the two ported vacuum thermal switches are bad. The full manifold vacuum that goes into one port is getting sent all the way back up the chain to the ported vac connection on the carb, screwing up pretty much everything. I can get new ones easily, about $35 each. In the meantime, I have plugged the manifold vac hose which seems to only affect the thermac door on the aircleaner.

EGR Issue

I'm having an issue with my '76 regarding the EGR valve operation. The old valve was weak, so was letting exhaust gas pass even with no vac signal. I replaced it with a new valve and it turns out the real problem is that it is getting a vac signal even at idle, so the idle is real rough when the hose is connected. I went all the way back to the carb and it seems the ported vacuum point on the carb body has vacuum at idle too, so the various temp switches are just passing it on. Ported vacuum should be zero at idle, right? Is the Q-Jet due for a rebuild then?

Passenger side mirror finally correctly aligned and functional! I had gotten a electric unit off of an '80s Buick some time ago and replaced the manual, dealer mounted original. I had even made a space in the dash for the control and ran the wires over to the right A-piller. But that was where it sat for quite a long time. But recently I found the head was coming loose and the angle has never been right anyway, having adapted the '80s car mounting arm to the '76 door in a not so great way. Again, quite some time ago I had gotten a correct, cable-controlled '76 model mirror on eBay, figuring I'd use the correct arm when I got around to wiring up the mirror the rest of the way. So this was the weekend make it all come together. New arm nicely mated to the '80s electric head and wired up so it's working beautifully. I tapped the power and ground for it from the clock, as it was convenient and close by.