hissing sound after shutdown

yotekiller · Mar 11, 2023

Has anyone had a hissing sound after shut down, i can't seem to find it, i suspect injector leak but not 100% sure..
Anyone else heard such before?
I did put an inline one way valve near the tank and now i have fuel at the filter head, since day 1 i been diagnosing and chasing fuel draw back, no leaks of fuel anywhere so one thing at a time, this hissing air sound has me puzzled..

Thanks for all the past help you guys are life savers.

franklin2 · Mar 11, 2023

Check the vacuum system. Disconnect the pump and see if it goes away.

CDX825 · Mar 11, 2023

Probably a vacuum leak. Check your brake booster.

IDIBRONCO · Mar 11, 2023

CDX825 said:
Check your brake booster.

That's where I'd put my money. I've heard them do that before. Sometimes, you can pump the brake pedal a time or two after engine shut down and the sound will disappear or change. That's a sure way to tell.

quickster · Mar 12, 2023

Those vacuum lines tend to rub on parts and get worn thru very easily. Air filter cover did it to mine.

Old Goat · Mar 12, 2023

Brake Booster. Mine was doing that under the dash when slightly pushing on the peddle when engine was off. That is when I noticed it. Didn`t really hear it when the engine was running.
I talked to an older counter guy at NAPA and he said it was normal to do that...didn`t sound right to me.

Finally replaced it with another "rebuilt" but got it from O` Really`s. That was what the problem was,
truck finally stops w/o having to stick my foot through the floor against the L/F Tire to slow it down.

Goat

yotekiller · Mar 12, 2023

thanks fellas...
soon as this weather clears up and warms back up i will ck that brake booster and vac lines...
i would have responded sooner but i did not get any alerts for some reason..

Old Goat · Mar 12, 2023

I have gone through 4 Boosters in the 8 years I have owned this truck, "Rebuilts" are a krap shoot. Finally got one that really tightens up the Binders.

Majority are done in Mexico from my experience.

Be alert, we need more Lerts...

Goat

hissing sound after shutdown

yotekiller

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franklin2

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CDX825

filtration nut

IDIBRONCO

IDIBRONCO

quickster

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Old Goat

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yotekiller

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Old Goat

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