SO I'm reading that the vacuum tank should be on the passenger side wheel well area.? The references indicate it's either a ball or flat pancake style unit? From my previous post about the vacuum line to the water valve, .....I'm trying to trace out the vacuum lines and the manual I have shows a vacuum tank that I can't find. ? Where's Waldo sort of thing I guess. Thanks in advance.

 

I have ‘66’s, not ‘75, but depending on amount of vacuum accessories installed, at least in my year, some cars had a small tank, some got a big one, some got multiple tanks connected in series.

Also over the past 50 years, it’s also possible a previous owner discarded it for leaking or it never had one if the vacuum needs are very basic.

By ‘75 a few accessories that had been vacuum in the ‘60’s had long since converted to electric solenoids - things like power door lock and power trunk releases. I suspect with the main vacuum accessory being the heater/AC system, your car had a smallish tank - likely the ball shaped one. If it’s missing and the engine is running the A/C/Heater shoudl still work, just not with the engine off.

It shouldn’t be too hard to find a reproduction unit or one from a junkyard, or check EBay for a similar year A-body (Chevelle, Skylark, GTO/Tempest) for the vacuum reservoir and you should find the part you need. Then it’s pretty much dealer’s choice on where to mount it. I’d follow the factory site if it were me, but you may want it somewhere different.

Cheers
Chris

 

I found this photo online that says its a 1975. I added an arrow to show where the tank is on it.

 

Thanks for the reply. Appears mine is MIA but the vacuum needs I beleive changed as prior owner stripped out all the pollution stuff. The diagram for the HVAC vacuum lines appears to have it in line. While sniffing around I did find my broken 1/8" hard vacuum line that goes to the heat /water control valve on the manifold. I've ordered some 1/8" line to fix it as the hard plastic one broke. The line that broke is right near the blower motor.. In looking on the inner wheel well I don't see ANY holes for mounting that vacuum tank. I found the service manual diagram (attached) for what I believe is the correct routing for vacuum lines.. On my car, there's no vacuum tank and I don't see the Air Inlet Diaphragm. I don't see a orphaned vacuum line that would go to the air inlet diaphragm! There are three of the hard plastic vacuum lines (1/8") going into a area near the blower. There's one from the Vacuum port coming off the maniforld left rear of engine, then there's the "white" line pictured that went to the water valve that I will replce as soon as I get some tubing to do that and lastly there's one more line going through the firewall that I suspect goes to the heater & a/c control on the dash?
Do I NOT need the air inlet control valve and if so where would that have been mounted?
I'm going to see what happens after I hook up the broken white vacuum line....would be phase 1 of my troubleshooting. If that takes care of my main issue which was having heat come out of the heater as that control valve was not shutting and was in the "default" open position for lack of the vacuum line to it!
Any other ideas as to what might be missing?

 

A vacuum reservoir is an easy thing to mistake for part of an emissions system if you’re new to car modifications.

If an inexperienced someone ripped out emissions stuff, it’s not at all surprising you have some open lines to nowhere and missing reservoir.

Chris