Ok I bought a Mightyvac pump kit.
-I have all of the new headlight lines installed and the 3 long lines coming to the vac tank.
-Off the tank I have 2 lines running to the 2 into 1 valve and then into the fiter,
-I have the line that goes to through the firewall clamped shut with vise grips.
-I connected the vaccum pump to the line at the filter and started pumping.

I probably sttod there for 3 minutes pumping the gun and it never came off zero. What am I doing wrong???

 

Your system has a leak?

Isolate parts at a time until you've checked it all out. Actuator seals and control valves are prime targets.

 

Thats a big job for that little Mightyvac, you have 3 actuators and a big tank your trying to pull down.

 

That is a lot of volume to pull down with a hand pump. An electric pump, like for a/c systems, is better. That way it pulls down fast, close a valve to isolate the pump, then watch the gauge to see if you have any leaks.

 

Ok I definately have a bit of work to do. The passenger side can holds both up and down preasure without leaking. The drivers side is good on the up which is the red hoes but has a slow leak on the green hose port. According to the troubleshooting guide I need to replace the seal around the plunger shaft.

Both override switches are good. as well as the check valve.

Here is where I think I have a problem. Both relays open and close the valve smoothly when vacuum is applied to the small port at the top of the relay. However, When I block the red port off and draw vacuum on the yellow (center port) I cannot get any vacuum at all. According to the site below I should maintain vacuum. I would have thought that I would get come vacuum but it would drop quickly. Howver I am getting no vacuum at all. So am I right in assuming that both relays are bad since both failed this test???


http://www.corvette-101.com/relays.htm

Thanks
Wade

 

Hi Wade,
I'm not just trying to get you to spend money.... but.... the trouble shooting guide that Dr. Rebuild sells for a few $$ shows how you can test each component individually to see what's working properly and what's not.
Regards,
Alan

 

To get the vacuum to go from the yellow to the red you have to apply vacuum to the small port also.

 

Test #3 looks like I did wrong...:o

TROUBLESHOOTING: Disconnect all 4 vacuum hoses. Remove the filter at the base of the relay and inspect it for damage and to make sure it isn't clogged. If it is clogged, the headlamp doors may open slowly.

1. Block off the green port and attach the vacuum pump to the yellow port. Vacuum pressure should be maintained. If not, the relay should be replaced. Failure of this test does not mean the relay will not function at all. What it does mean is that once the car is turned off, the holding tank will not hold a vacuum because the yellow port is always open to the vacuum storage tank.

2. Apply vacuum to the small metal port and note if the valve moves freely up towards the diaphragm. If is doesn't, the valve is frozen and the relay needs replaced. This test was successful

3. Release the vacuum at the small metal port. The valve should sharply snap toward the filter end. Slow movement indicates either a worn spring or the valve is sticking. This will cause the headlamp doors to open slowly. This test was successful

4. Apply vacuum to the small metal port. Pinch off this hose to maintain vacuum pressure and remove the vacuum pump. Block off the red port and apply vacuum to the yellow port. If vacuum is not maintained, replace the relay.

 

Well that didn't work. I pulled 20hg of vac onthe small port which opened the valve. I clamped the line and it held the valve open. I then blocked the red port and hooked the hand vac up to the yellow port and could not pull any vacuum. The canister itself held steady.

So in thinking about this was I checking to see if I could build vacuum or was I testing to make sure I was not removing vaccum from the canister by the valve?????

I am so confused!!!

 

If the engine is operational, I never really understood why one needed a vacuum pump to check out the vacuum systems in a C3. Just fire up the engine and the vacuum [supply] is already there. What you need is a vacuum gauge (your vacuum pump may have one so you can still make use of it). The strategy for finding vacuum leaks can be summarized as follows:

1. Determine the maximum vacuum capability of the engine at idle by disconnecting all but one of the vacuum supply lines from the carb and intake manifold and sealing all of the open connections off. Connect the vacuum gauge to the remaining line so you can measure vacuum level. Don't forget the distributor advance can; you may need to loosen the distributor and adjust it for maximum reading [with advance can disconnected]. Then hook the advance can in the circuit and reset the dist. for maximum vacuum level. If the max. vac. level is the same for both conditions, leave the advance can hooked up for all other tests; if not, replace the advance can.

2. Connect the main feed line from the manifold up to, and including, the vacuum reservoir tank. Cap off all outlets from the vacuum tank if you can. This tests the feed line, the filter, check valve and vacuum tank for leakage. When this test is completed, shut the engine off and see how long it takes for the tank vacuum to bleed off. If it doesn't hold vacuum well, your check valve may be bad.

3. Add one section of the vacuum system back in [at a time] to see if that section will still maintain the same level of vacuum as measured with your 'baseline' check [with all systems removed]. (engine running, of course) Any one section should not cause more than 1" Hg loss to the baseline reading. If it does, then there is a leak somewhere within the system you just reconnected. You must continue diagnosing that section by dividing it into smaller segments and re-testing, until you isolate the leakage and fix it.

4. Continue this process until all sections (supply/tank, headlights, wiper door, heat/A/C, distributor, emissions) have been analyzed and resolved.

This is not a difficult process...but it does require a gauge, some patience, being organized and methodical, and a bit of time. Generally, the results are the successful repair of the vacuum system--usually for a relatively small amount of money. Most components in the system can be repaired, rather than replaced, if you are mechanically competent. Good luck.

 

This is the next project on my list that I am working on. All the components were in a box from when I purchased the car. There isn't a vacuum port on the intake yet. I am trying to bench test the components with a handheld pump and guage before putting them on the car. If everything were already on the car and connected you are correct using the engine as the vaccum source would be the ideal method. Right now I have a box of new hoses and a box of parts to sort through.
It does appear that both relays are bad. I did see that there was an R&D method for the relays but it also stated that it may or may not work. Wilcox had them on forum special for $38 a peice new. I did get the new seal and boot kit for the actuators as well as a new filter.