spfulfill

The vacuum tank/reservoir (the one mounted in the driver fender) on my '72 is leaking. I've purchased and installed the vacuum overhaul kit and relays, which are easily found online, but cannot find this tank at any of the typical catalog companies. I'm finding things on ebay used for $120 and new for $230, but it's odd to me that there's nothing in the catalogs to replace this. I can find one for 80-82 for $50 easily, but I'm not sure why there's nothing for any other C3. Does anyone know where there's a reasonable replacement or has anyone had experience fixing or replacing with something different?

Alan 71

Hi s,
Welcome!
First Post!
And a 72!!! Nice!
The tanks do sometimes end up leaking. Some folks have success in repairing them depending just what the problem is…. rust ?, a crack?, a leak at one of the hose connection pipes?.
You're right. There isn't anyone making reproductions of these tanks so you're limited to repairing yours or buying a used original or maybe an nos tank.
There certainly are other vacuum tanks you can use but what you choose might depend on if you're concerned about the 'originality' of your car.
Getting the old tank out in any case is a bit of a hassle that involves moving the master cylinder out of the way. The tank can't be dropped down under the car and is too odd shaped to bring into the engine compartment without moving the master cylinder.
Good Luck!
Glad your here!
Regards,
Alan

Always like to see pictures of member's cars!

spfulfill

Thanks for the quick reply! I just wanted to make sure I wasn't missing anything in case there was one available somewhere. Not too concerned about the originality, so I might just try to use a Summit Racing vacuum reservoir that I have laying around...

Alan 71

Hi s,
As I said getting the old one out is a project.
On a std brake car the master cylinder needs to be unbolted from the firewall pulled forward and then pushed toward the engine.
On a pwr brake car the booster is in the way too.
Good Luck!
Regards,
Alan

Mooser

I've never opened a tank up but always figure it's just a plain box (no valves or anything???)
If it's not completely rotten or anything I would think using one of the kits for sealing a gas-tank should work. The type you pour in and then rotate the tank to coat the insides and let it dry. I think they even make smaller ones for motorcycle tanks that would be lots. POR15 etc.

Any yes, removing that tank is a PIA
https://www.corvetteforum.com/forums...k-removal.html

M

Hammerhead Fred

It only hold air/vacuum - sealing it is easy as there are many options.
As stated above though - getting to it is the trick.
IF you can get it out - pressurize it OR hold it under water OR fill it with water to check for leaks.

Haggisbash

I had a leak in the vac tank in my '70. I disconnected the hoses from the tank and blocked off the outlets, connected a compressor to the inlet, pressurised the tank to 5 psi quickly found a split in the tank on the outer side. Luckily I could reach the split with my fingers and because removing the tank is such a pain I opted to patch the split with a piece of fibreglass cloth soaked in resin, this worked a treat.

jim2527

It's been awhile since repairing mine but I may have used JB Weld.

theandies

So here's a thought. If the tank is leaking why not bypass it? The only reason for the tank is to store vacuum to allow the headlights and wiper door (if equipped) to raise and lower, I think the owners manual or I read somewhere, 3 times without starting the engine????????
I don't think I've ever been in the situation where I needed to do that.
What do you guys think?
I know mine leaks but just looking at the location I've not messed with it. Just seeing this thread reminded me of it and I have my engine out for a clutch swap and other things and now would be a perfect time to do this while waiting on parts. If anyone has ever bypassed it without any negative effects I may just do that. My wiper door and headlights open and close fine at this time (after a lot of work lol).

Alan 71

Hi ta,
I believe you're right thinking that the headlight and wiper door system can operate without the tank.
The purpose of the tank is to supply a limited amount of vacuum without starting the engine.

" My wiper door and headlights open and close fine at this time (after a lot of work lol)."
Working headlight doors and wiper door are a beautiful thing!
Regards,
Alan

7T1vette

There is no need to open up the reservoir tank. It is a VACUUM reservoir...which means that it is leaking INTO the tank, not OUT OF the tank.

If you find damaged areas on the tank, patch them with epoxy on the OUTSIDE of the tank. Clean the surface, cut out or wire brush off any loose stuff, put a patch of JB Weld stick epoxy over the area to be sealed...and make it look as purty as you can. Paint it satin black, if you want. Then just put it back in place, once you are sure that it is sealed, again.

If you want to replace it (can't imagine why), you can find good used tanks at most Corvette parts swap meets.

sierra 43

On my 74 I did bypass the vacuum tank. Mine is in the front of the car, so it was easy to get to. I was having trouble with the lights going up and down. I used a Y fitting. The main vacuum line into the top the Y and the headlight regulator lines to the other ends. Boom lights work fine now.