Billy Baroo

I was driving around on Father's Day and everything was great until I pulled into my driveway and the car started to run rough. I started it up today and it continued to run rough and it wouldn't rev past the idle. While it was running the headlight doors opened and my wiper door opened without being switch on?!? I sprayed cleaner in the carb with no success. Anyone have any ideas on what's going on? How can a rough idle effect my headlight and wiper doors?

Thanks, Andy

BarryK

sounds like a vacuum leak.

a vacuum hose may have popped off somewhere, a check valve may has gone bad, etc but it definitely sounds vacuum related

Eldogg

Sounds like you have a vacuum leak to me. I feel you! I'm fighting one right now also.
Eldogg

400hp427vette

If its running really rough. It may be a intake manifold leak, If a hose popped off you idle speed would increase. Both could cause the headlight & wiper issue. Good luck

Billy Baroo

Everyone warned me that this would be a problem at some point in my c-3 experience! Any recommendations on where I should start to look for the leak? I'm new to this problem!

Billy Baroo

What's the best way to check for a leak in the manifold? Do I need to take it off and replace the gasket? I do hear a hissing sound when it is idling. It gets louder when I hit the gas.

bvanpelt

Where to look: Cap the big vac line between the vac filter & the 1-way-valve/splitter. They're along the firewall between the wiper motor & master cylinder. The rough idle will probably stop. If it does, google the vacuum diagram for your car & start looking at hoses. If it doesn't, look close to your engine. I'm voting for a hose failure. Let us know?

400hp427vette

when at idle cover the carb with your palm you should feel alot of vacuum, if not you know its something after that

Bronze76

The best way to find vacuum leaks is to grab a can of carb cleaner and spray it around the suspected area. If the idle speed increases, you have found a leak.

Start at the carb first. Test the carb to intake area, then check the shaft bushings (these are like little axles that has the linkage pieces on the exterior of the carb and open the venturi blades inside the carb). Don't forget about the vacuum ports at the rear of the carb at the base.

Move on down the line from there out to the brake booster, check valves, tees etc.

The vacuum lines for my headlights broke by the hood hinge area. It was hard to see but something rubbed through the lines there and started the leak.

Good luck!

Billy Baroo

Thanks for the advice guys. I'll try all of these suggestions and let you know what I come up with!!

jdp6000

Narrow it down a bit. Disconnect the hose that feeds the headlights as suggested above. Its on the drivers side. Plug the port. Start the car. If it idles properly you know its in that set of components. Next is to check the hoses and components. It could be in one headlight or the other, the can, the pulldown switch under the steering wheel, the headlight switch,etc.

Do you have power brakes? There would be a hose that goes to a one way valve on the brake booster. The one way valve sometimes fails.

Vaccum keeps everything from opening not the opposite. So what you are getting is a loss of vaccum at some point for some reason.

Jim

Billy Baroo

JDP6000,
Thanks for your ideas. I have started to plug a few hoses but have not had any success yet. I also tightened all bolts on my carb and manifold; still didn't help. The saga goes on! I'll keep you posted.
Andy

Billy Baroo

I couldn't feel much, if any, vacuum when I covered the carb with my hand. I have a feeling that it's not the headlight/wiper system where I'm losing my vacuum. My car barely runs with the whole block shaking (can that be from the vacuum system?). I have to keep hitting the throttle with my hand to keep it running. As suggested earlier I'm going to try and spray the carb cleaner around the carb and intake manifold to see if I can get any results. I hope this doesn't drive me to my grave.

If anyone else has any other ideas I'm all ears.
Thanks, Andy

72LS1Vette

If you have a power brake booster, are your brakes working normally? There is a big vacuum line to the brake booster and if the seal around the shaft going into the master cylinder failed that would cause a big leak. Also check the vacuum reservoir to see if it has sprung any rust holes. Most likely you have just a split hose or a failed actuator but finding the culprit can take some time.



Rick B.

Billy Baroo

No power brakes. I'll keep searching.

Thmprr

Is an auto transmission? If so, it's common for the vacuum line to the modulator to come off, causing a vacuum leak. To check this out you would need either to observe under the car to see if the steel line is connected to the modulator at the rear on a TH350 or the side on a TH400. Another way is to disconnect it at the manifold, just to the front of the distributor behind the carburetor on the passenger side, and plug it, if that fixes it you need to reconnect it down below at the transmission modulator.
Other vacuum source leaks are (besides headlight actuators):
- PCV hose
- distributor vacuum hose
- smog hoses off if still fitted to car.
- carburetor gaskets and port block off plugs

Another way to trace the leak is to get a yard of garden hose, run the engine and put one end to your ear, then move the other end around until you get the maximum sucking noise which will be your leak.

jdp6000

Sounds like you have a totally different problem.Aside from the headlights and wiper door there isn't much there that runs off vaccum. It sounds like the engine is not generation enough vaccum to keep the lights closed. Probably because the idle is so low. It could be some other type of mechanical failure. Do you have an egr valve? Check and see if its closing.

What else is it doing? You start it. But when you give it gas no matter what you can't get the idle up? Is it back firing? smoking?

Jim

Billy Baroo

JDP6000,
You're right, I can't get it to pick up the idle at all. It doesn't back fire and there is no smoke. Yes, I have an egr valve. Any ideas?
Andy

jdp6000

Strange for this to just start with no other symptoms. 68 327 motor is pretty basic. Gas/air /spark. When is the last time you turned it up? Bad gas?

Look at the coil and cap. One plug or one wire would not cause that problem so its got to be something that is effecting everything.

Are you getting fuel? What if you pour some fuel down the carb any change?

Look at the carb. Everything appear to be working?

I'm not sure if the egr would cause that problem on a none HEI engine. While running push up on the bottom of the egr diaphram if its fine it will make a change in engine performance.

Jim

Billy Baroo

My first thought was bad gas. Now I'm thinking my first guess might be right. I put a 1/2 tank of gas in at a Shell station about 30 minutes before this started (93 octane). What's the best way to see if this is the problem? Can I add something to the tank? Should I pour new gas down the carb to see if there is a change? Everything on the carb seems to be working and the fuel flow seems fine too.

Thanks, Andy