Vacuum leak question question

[retirednak]

In an earlier post,my problem (besides me) might be a vacuum leak. If I cut the vacuum line where it Tee's off going into the cab. (middle of the upper firewall) and use my air compressor to blow air into the line going into the cab and then into the line that goes toward the driver side. Will I screw up or break anything if too much pressure goes into the line? The only thing I have to blow air into the line is a air chuck w/rubber tip. I don't know of any other way since I can't hear a leak with the engine running.

Does anyone have another idea how to pressurize the system to find the leak? Last question,if blowing air in the line turns out to be OK,would I cause problems if I was to use some of the coloring stuff that is used to find engine leaks,the coloring stuff you pour into the engine oil. (not sure of the name) I used it once to find a small oil leak on a commuter beater I use to have. It worked great since there was old oil leaks that I never wiped off. Had to use a black light for the coloring to show up.



Thanks fellas

Casey

 

[Hoefler]

I would not use air pressure in a vacuum system, you could really mess it up, the diaphragms and such. Use an A/C evacuation pump.

 

[rscurtis]

Best yet, if you know someone with a smoke generator, that will find your leak in an instant and not damage any components.

 

[retirednak]

I don't know of anybody with a A/C evacuation pump or a smoke generator.

It seems like I remember a link on how to build a smoke generator quite a while back,I'll have to do a bit of research and see if I can find it. If anybody knows about the link,please speak up.

Thanks-Casey

 

[jelag]

If you get a vacuum gauge, all trucks with power brake boosters were designed to hold vacuum for 2-3 minutes after the truck is shut down, so that the brakes will have boost. Even though the trucks no longer have a vacuum brake booster the same applies... there would be a constant vacuum in the system for several minutes if the valves in the vacuum pump are good... .

Another simple test would be to run the truck at high idle, hold your finger over the end of one of the hoses and shut the truck down... wait a couple of minutes and pull your finger away... you should fell the rush of air as its sucked into the system... . if your hand isn't sensitive enough let the hose rest against the back of your hand or forearm. . in either case it should hold vacuum...

you also might consider an air regulator, set at 2-5 lbs like you'd inflate a kids ball... . let it run and spray the connections with soapy water... .

On a gas engine you just spray the connections with carb cleaner and wait for the engine to race from the extra fuel once it reaches the engine. .

Hope this helps. .

 

[retirednak]

I didn't think about using soapy water to look for the leak. I also have a vacuum guage and will see if I might be able to rig it up.

Thanks for the ideas!

 

[Hoefler]

You can purchase a hand vacuum pump at the auto parts store for $30-$50. I would never pressurizer a vacuum system.

 

[retirednak]

I do have a hand vacuum pump from a cheap brake bleeder that didn't work. I'll give it a try,I know it won't pump much pressure since it wouldn't build enough pressure to move brake fluid.

Thanks for the idea. I guess I shouldn't have inhaled when I was younger,I should have thought of using it.