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Vacuum Leak?

Forum: C3 HVAC, Fuel, Emissions, and Exhaust

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Vacuum Leak?

Posted: 8/23/04 6:38pmMessage 1 of 7
m
Former Member
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Tecumseh, MI - USA
Joined: 9/14/2003
Posts: 221
Vette(s): 1980 all org. with 18000 act. miles dk claret with matching interior..Eagle alloys ..loaded..excellent cond.
Have developed a rough idle on my 80 Vette. Changed the carb to intake gasket last week-end, but did not cure problem. Car runs fine cruising down the road, but at a stop light, I have to put it in neutral to keep it running. Problem seems to come and go. Car has only 19000 mi. on it. Sounds like a vaccum leak somewhere, but can't find it. |headscratch|
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Vacuum Leak?

Posted: 8/23/04 7:22pmMessage 2 of 7
S
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CONCORD, MA - USA
Joined: 6/12/2002
Posts: 185
Vette(s): 78 Silver Anniversary (2 Tone) L82 auto loaded
Your car has a lot of miles on it. Probaly every hose needs to be replaced.Put the carb on fast idel and spray some choke cleaner on everything-when the engine speed picks up you found the vacuum leak!
Steve |wavey|
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Vacuum Leak?

Posted: 8/23/04 8:52pmMessage 3 of 7
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Hot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
 Steve said: Your car has a lot of miles on it. Probaly every hose needs to be replaced.Put the carb on fast idel and spray some choke cleaner on everything-when the engine speed picks up you found the vacuum leak!
Steve |wavey|
 


or if you have oxy acetylene tanks turn the oxygen on ONLY.. and move the head near an area you suspect a vaccum leak.. when it sucks in pure oxygen the engine will rev..

i would take all the vacuum hoses off the engine and plug everything.. then add things on one by one until you find the leak..
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Vacuum Leak?

Posted: 8/24/04 5:13pmMessage 4 of 7
b
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Pasadena, MD - USA
Joined: 6/16/2004
Posts: 315
Vette(s): 72 Coupe L48 4 sp Air Tilt Leather
All of the suggestions sound cool, but do the easy thing first and isolate the vacuum system from the rest of the car. Just plug off the vacuum port(s) from the intake and see if the idle returns ok. This leaky situation causes a lean condition in the rear two cylinders and make a rough running baby. Had the same problem on mine and most likely it will be in the headlight circuit. ( 80's have vac lights? ). Had to eventually replace everything, as the vacuum leaked a tiny bit from everywhere and added up to one big one. Expensive repair, but she ran great again till I decided to fix the horn and eventually the fatal restoration vortex swallowed me. Good luck....it can be done. |biggrin|

Bruce
72 Coupe L48 4sp
Custom Blue/Silver/Pearl

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Vacuum Leak?

Posted: 8/24/04 5:52pmMessage 5 of 7
m
Former Member
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Tecumseh, MI - USA
Joined: 9/14/2003
Posts: 221
Vette(s): 1980 all org. with 18000 act. miles dk claret with matching interior..Eagle alloys ..loaded..excellent cond.
Thank's for the imput guy's. Will try your suggestions this week-end and hopefully find the problem
| |thumb| (19000 mi.not 190000 mi.) |thumb|
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Vacuum Leak?

Posted: 8/26/04 6:48pmMessage 6 of 7
m
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Tecumseh, MI - USA
Joined: 9/14/2003
Posts: 221
Vette(s): 1980 all org. with 18000 act. miles dk claret with matching interior..Eagle alloys ..loaded..excellent cond.
Found the vaccum leak |bouncy| Replaced the EGR valve gaskets and everything is fine. Thank' for the imput guys
|cheers|
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Vacuum Leak?

Posted: 8/26/04 8:51pmMessage 7 of 7
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
|thumb| |thumb| |cheers|
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