Hissing sound

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For some time now my truck has hissed for 8-10 seconds after I shut the truck down. It sounds like it is coming from the front of the truck near the radiator, but I can find no problem or where it is coming from. It is kind of annoying and none of my friends have this problem. Has anyone of you ever experienced this?
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1997, 3500 club cab slt,4x4,5 spd,4. 10 rear end,no cat,no muffler,110 gal fuel tank,BD exhaust brake & 60 lb springs

 

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You might try tighting the clamps on the intercooler pipes and hoses.

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Joe George
Eureka, CA

'95 2500 CC auto 4X4,3. 54,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver

 

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If you have been running with the defrost or AC on it will hiss after shut down. The turbo also takes about 10 seconds to quit spining(spool down)Normally you would hear this noise from the air filter or tailpipe area,unless as Joe says,you have a loose clamp. My bet is it's the AC,try shuting down in any other mode than AC or defrost.

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95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(Play truck)95 3500,5 speed,Driftwood,Banks&Phscotty,34,000 GCVW apple and tractor hauler(work truck)

 

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Joe I have tried that to no avail. If those clamps are loose doesn't it hiss during operation as the turbo pressurizes the system and it leaks

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1997 3500,4x4,slt,club cab,4. 10 limited slip,5 spd,BD exhaust brake & 60 lb sprinds,no cat,no muffler,110 gal. fuel tank, work truck-hauls a D5 dozer,310backhoe,and everything on the farm

 

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Illflem Thanks for the advice, that's the only thing I haven't tried(in ac or defrost). Sounds like you work you're truck too. I live about forty miles from where they make the fords, no one around here can get much more than 150,000 miles out of them working them the way we work these dodges. They can't get the mpg my friends and I are getting out of dodges.

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1997 3500,4x4,slt,club cab,4. 10 limited slip,5 spd,BD exhaust brake & 60 lb sprinds,no cat,no muffler,110 gal. fuel tank, work truck-hauls a D5 dozer,310backhoe,and everything on the farm

[This message has been edited by jeff harrod (edited 11-28-2000). ]

 

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A couple of years ago, I had a leak on my inner cooler, it wasn't the clamps, it was the metal pipe between the inner cooler and the intake manifold, where it made a 90 degree bend. The pipe was split, it was leaking to much air to give a person a hissing sound, but if it would have been a smaller hole, then it probably could have. It was an easy fix, but I still check it once in a while.

Rodney

 

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Yeah Jeff,my 3 axle 12 wheel 28' gooseneck gets loaded to the max at times. Moved a D-6 high track with it a couple of years ago,won't do that again,only problem was brakeing,a 3500 just isn't heavy enough,the Cummins had no problem. The Psycotty unit was the best thing I've added for heavy hauling,you should try one.
As far as the hiss,I didn't know what it was till I asked a dealer and he told me about the AC coming on in defrost,owners manual doesn't say a word,there is a way around it though- Check here

 

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My truck does this also. It is the A/C on mine . I would say that is what you are hearing.

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1994 4X4 2500 Auto.
1998 Harley FXDS
1998 Harley Sportster 1200

 

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I too believe it's either the A/C or Defroster being on when you shut it down

 

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I get the same hiss. My hiss is from the AC too.

Story: My dealer troubleshot my complaint of defroster "frosting more than defrosting" and traced the problem to my disconnected AC (I figured "what the **** do I need this for anyways?). Consequently, with the AC working in the defrost mode, my windows stay drier. I just leave it alone and tell my buddies that the hiss is the pumped up turbo still screaming to let the air out...

 

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Like others I have only noticed the hissing sound after running the A/C. I read the reference article on Fritz's web site that Illflem refered to. My question is why does the A/C come on when the climate control knob is in a defrost mode? I have always wondered why my A/C clutch engages when the fan is on (especially in the winter). If this function is disabled will it affect the A/C system. On older vehicles with A/C I remember always hearing you need to run the A/C periodically in the winter to keep the A/C pump seals lubed to prevent them from drying out leaking.

 

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1tuffram,the idea behind running the AC in defrost mode is that the AC dries the air and defrosts better,it also exercises the AC components in the off season to keep seals and hoses healthily. Problem is sometimes it's to dam cold to run the AC when defrosting and many times the drier air isn't necessary,the AC also sucks quite a bit of power. The mod from Fritz's site allows you to chose when you want AC defrost,you're not stuck with something Dodge figured was right for everybody. It will not effect the AC whatsoever.