Fay vette

I have 2 vacuum lines that change to wires. One looks like it goes from a shut off of the hotwater line to heater core. The other goes off a tee off the drivers side of the 3 pronged valve on the intake manafold. The wire then goes back behind the distributor somewhere.

How do these work, what is their purpose?

Also in that vacuum line off the drivers side of the 3 pronged valve on the intake manafold is a little round disk that looks like an in-line fuel filter on a lawnmower. What is this, what is it for?

Durango_Boy

They are not changing to wires, just smaller more hardened vacuum lines. They provide the vacuum for the shut off valve. That three prong tree is where that part of the system gets it's vacuum.

That disk is a check valve to keep the vacuum going only one way.

Fay vette

OK Thanks

Can someone explain how to splice a new section of hose onto one of these little vacuum wire/hoses. This may be my vacuum leak the rubber hose (very short piece) is old, hard and brittle and will not stay on barbs of the fitting. I bubba-ed it with electical tape and car seemed to idle better but it was raining so really couldn't test.

Durango_Boy

I have never had to replace any before, but I think some of our vendors sell stock diameter vacuum tubing, and might be able to help you. Chances are if you have one leak you'll have more than one, and it's best to replace the entire length, but patching might work using vacuum tube with an inside diameter the same as the outside diameter of the bad tubing. Just use a small amount of silicon on the outside of the old tube when you slide the new on, and let it cure.

AimHigh

a temp fix for stiff or brittle lines is to get a swab or small towel or such and soak it in armor all or equiv and then wipe down the rubber line with it. The line will soak up the juice and get malable. Take your time and have patience.

Petroleum jelly works too but remember most of these products will eventually break down rubber, especially the p/j.

word of caution this is only a temp fix... some lines are old and done for and need to be replaced, but maybe this will help you get back up for now.

bmotojoe

From the barb fitting on the tee facing the drivers side there actually should be 2 disk like fittings. The first one after the barb should be white in color, this is a filter only. The second one inline is made of metal with a single port in and a duel port out. This is the check valve.
You can cut a short piece of the hard line out and take it to your local auto parts house. Have them cut you a length of vacuum line that fits the OD of the hard line. Use a shot of silicone spray on the hard line to make the new rubber line slide on a bit easier.

Fay vette

I have both those disks, one line goes off that 1 to 2 disk and goes throught the firewall somewhere (I think its a smaller dia. rubber hose line). The 2nd goes about 10 inch to a plastic tee (the tee was bad, I replaced it). The one off the tee goes to the headlights. The other is the little piece of rubber hose that is hard/brittle (their is maybe an inch of rubber) with thes little wire hose line glued in to the little piece of rubber hose. What does this go to?

bmotojoe

What line are you talking about? The hard white line going to the hot water shut off heater hose valve? Pictures would give a better guess on the problem area.

jnb5101

the small vaccum line outer diameter is the same as the inner diameter of regular(1/4") vaccum line. carefully cut the small line with a razor knife to prevent cracks, clean thoroughly it's outer surface and the inner surface of the regular line, coat the small line with weatherstrip adhesive(keep it away from the end to prevent blockage) and slide it into the line about an inch.

Fay vette

I will get some pic's tonight. Their are 3 sizes of line, 2 rubber (it looks like one will fit the other but thats not what I need to splice) and one looks like a piece of wire (its green I think). Its the piece of wire looking one onto the smaller sized rubber. Current one looks like some type of hard black cement holding it in. The wire one is way smaller than the inside of the smallest rubber tube.

Fay vette

I fixed it, its bubba-ed with black electrical tape but its idleing smooth. bmotojoe can you post the pic's. What is this wire to/for? Anybody know.

bmotojoe

This is a picture Fay Vette sent to me last night. It is hard to see but there is a yellow circle around the end of the tee. This small line enters through a round rubber grommet behind the distributor on the firewall. This small vacuum line is the source line for your heater control system. After replacing the tee you applied tape to you are going to have to get a small length of regular vacuum hose to slide on the hard small vacuum line and connect it to the small end of the new tee I told you to look for on Corvette Centrals web site or have your local parts house match it up for you.
The second picture is one I have used for many years from Dr. Rebuilds web site I dolled up a little with the correct color codes for the 77 model. The red circle on the second picture is what that broken line is.

TFitz

go to Napa, they sell small packages with various size barbed fittings to make splices and repairs

AimHigh

Silly question...but what does the manual show (assembly) ? I'd be lost without that thing.