Engine hissing
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Joined: Dec 2007
Posts: 7,986
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From: Boise, Idaho
About the only thing over on that side of the engine vacuum related that I can think of is the brake booster.
Next time it does it, take a length of heater hose or the like and put one end to your ear and move the other around the engine bay (if possible, cover your other ear). The noise will grow substantially louder in the hose when you put the opening over the source of the sound. It'll help you track down its origin a bit easier.
Next time it does it, take a length of heater hose or the like and put one end to your ear and move the other around the engine bay (if possible, cover your other ear). The noise will grow substantially louder in the hose when you put the opening over the source of the sound. It'll help you track down its origin a bit easier.
Junior User
Joined: Sep 2010
Posts: 89
Likes: 1
From: California
Good answer
AB posted some good advice, the one thing I might add is that since the only thing on that side of the engine vacuum related is your vacuum advance unit and brake booster.........use a pair of pliers and pinch the brake booster hose somewhere and see if the hissing goes away. If it does, easy fix....probably the check valve but also could be the hose itself. Also the vac advance unit on your dizzy may have a vac delay valve. Those will hold vac for a really long time. Check that out as well by pinching the line on both sides of the valve....Mike
Oh, sounds kinda dumb but are all your spark plugs tight. The 'ol big six has (with good rings) enough compression to last for days after the engine is shut off. Do what AB said and listen at each spark plug.
Oh, sounds kinda dumb but are all your spark plugs tight. The 'ol big six has (with good rings) enough compression to last for days after the engine is shut off. Do what AB said and listen at each spark plug.
Senior User
Joined: Feb 2006
Posts: 109
Likes: 0
From: springfield
not ruling out the brake booster, just keep in mind that if its efi there is a bunch of stuff. could be the controlling valves/solenoids for your emissions near the firewall. could be the egr solenoid sticking and exhausting the vacuum can?
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