Vacuum leak????

69fastback · June 27th, 2008, 12:59 PM

I replaced the intake gasket on my car a few months ago because it was leaking oil, and coolant, and haven't had any problems since I changed it.

In the last few weeks my car has been staying idled up a few seconds after I stop before it settles into a good idle. I will come to a complete stop and it hovers around 1100-1200 RPMs, and then will slowly settle into a normal idle after I come to a complete stop.

If I downshift into first, and let the engine slow me down, I will wait until it gets to 700 RPMs, push in the clutch, and it will jump back up to 1100 - 1200 and then slowly settle back down. It will also occasionally backfire through the carb when I give it gas.

Except for the backfire, it kind of sounds like a vacuum leak to me. I don't think that new intake gasket is leaking, but I guess it could be. Could trash in the carb be casuing these symptoms?

460brevill · June 27th, 2008, 04:27 PM

try spraying around the gakets with carb cleaner and see if the idle changes.if it dose check that area for a leak.the pop back could be timeing.or air fuel adjustment.

69fastback · June 27th, 2008, 11:08 PM

Thanks I'll try that. The timing and air/fuel have been the same since the engine was built so I don't really see them being off all of a sudden.

Kobra Killer · June 29th, 2008, 05:25 AM

Could be something binding/dragging on throttle or dashpot linkages.
Also check vacuum advance on distributer & hoses.

69fastback · June 29th, 2008, 07:09 PM

Originally Posted by Kobra Killer

Could be something binding/dragging on throttle or dashpot linkages.
Also check vacuum advance on distributer & hoses.

I just got home from being at the lake all weekend, so I may go up and check it tonight, or I may wait until tomorrow.

The car doesn't have vacuum advance, and it doesn't have power brakes, so if it has a leak it has to be the intake gasket, the carb base gasket, or one of the rubber vacuum plugs on the carb.

69fastback · June 30th, 2008, 07:38 PM

I sprayed carb cleaner around the base of the carburetor, and the idle surged, so I tightened it up a bit, and it still does it, so I'm going to get me a new gasket tomorrow.

69fastback · July 1st, 2008, 10:20 PM

All fixed up. She runs like a new car.

June 27th, 2008, 12:59 PM	#1
69fastback Enthusiast 1969 Mustang Mach 1 OLDNSLO Join Date: Aug 2006 Location: Oklahoma jackass, get to driving Posts: 676	Vacuum leak???? I replaced the intake gasket on my car a few months ago because it was leaking oil, and coolant, and haven't had any problems since I changed it. In the last few weeks my car has been staying idled up a few seconds after I stop before it settles into a good idle. I will come to a complete stop and it hovers around 1100-1200 RPMs, and then will slowly settle into a normal idle after I come to a complete stop. If I downshift into first, and let the engine slow me down, I will wait until it gets to 700 RPMs, push in the clutch, and it will jump back up to 1100 - 1200 and then slowly settle back down. It will also occasionally backfire through the carb when I give it gas. Except for the backfire, it kind of sounds like a vacuum leak to me. I don't think that new intake gasket is leaking, but I guess it could be. Could trash in the carb be casuing these symptoms? __________________ New ride http://www.superior-motorsports.com/...aig/craig.html Old ride http://www.superior-motorsports.com/...g/mustang.html old rides engine in new home http://videos.streetfire.net/video/4...285480b970.htm

June 27th, 2008, 04:27 PM	#2
460brevill Enthusiast Join Date: Apr 2007 Location: Farmville VA Posts: 879	try spraying around the gakets with carb cleaner and see if the idle changes.if it dose check that area for a leak.the pop back could be timeing.or air fuel adjustment. __________________ i sixing 200 six with 300 hp.

June 27th, 2008, 11:08 PM	#3
69fastback Enthusiast 1969 Mustang Mach 1 OLDNSLO Join Date: Aug 2006 Location: Oklahoma jackass, get to driving Posts: 676	Thanks I'll try that. The timing and air/fuel have been the same since the engine was built so I don't really see them being off all of a sudden. __________________ New ride http://www.superior-motorsports.com/...aig/craig.html Old ride http://www.superior-motorsports.com/...g/mustang.html old rides engine in new home http://videos.streetfire.net/video/4...285480b970.htm

June 29th, 2008, 05:25 AM	#4
Kobra Killer Regular Join Date: Sep 2006 Location: Arvada, CO Posts: 122	Could be something binding/dragging on throttle or dashpot linkages. Also check vacuum advance on distributer & hoses. __________________ Clevelands Rule https://home.comcast.net/~jimmiephil...er_project.htm

June 30th, 2008, 07:38 PM	#6
69fastback Enthusiast 1969 Mustang Mach 1 OLDNSLO Join Date: Aug 2006 Location: Oklahoma jackass, get to driving Posts: 676	I sprayed carb cleaner around the base of the carburetor, and the idle surged, so I tightened it up a bit, and it still does it, so I'm going to get me a new gasket tomorrow. __________________ New ride http://www.superior-motorsports.com/...aig/craig.html Old ride http://www.superior-motorsports.com/...g/mustang.html old rides engine in new home http://videos.streetfire.net/video/4...285480b970.htm

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July 1st, 2008, 10:20 PM	#7
69fastback Enthusiast 1969 Mustang Mach 1 OLDNSLO Join Date: Aug 2006 Location: Oklahoma jackass, get to driving Posts: 676	All fixed up. She runs like a new car. __________________ New ride http://www.superior-motorsports.com/...aig/craig.html Old ride http://www.superior-motorsports.com/...g/mustang.html old rides engine in new home http://videos.streetfire.net/video/4...285480b970.htm

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