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-   -   12 valve with a terrible fluttering paper bag sound from exhaust. HELP!!! (https://www.dieselbombers.com/12-valve-2nd-gen-dodge-cummins-94-98/135603-12-valve-terrible-fluttering-paper-bag-sound-exhaust-help.html)

Fievalfon 02-24-2019 01:09 PM

It’s a nick name I was givin back in my mini truckin days about 20 years ago. Fieval was the nick name and FON is short for Freaks of Nature, a car club I was in at the time. Been using it as a user name and such ever since.

Fievalfon 03-11-2019 12:34 AM

Just a quick update for those who still follow this post. Installed a new adjustable over flow valve and just as I suspected there was no change. I’m not surprised but it was worth the $60 chance that it might have had something to do with it. Any new clues out there possibly?

JBearSVT 03-11-2019 05:12 PM

No, but the adjustable valve is nice. They wear out, but when the adjustable one starts to get worn, you just tighten it up a little bit and pressure is GTG again. This is the strangest 12v thing I've ever heard of.

windage 03-24-2019 11:24 AM

I too, would like to see the results of a compression test on all 6...you have not mentioned excessive blow-by and it appears that you may have addressed valve seating (with new head) and setting lash. Have you gone over the crankcase breather system to assure it's OK?
I was reviewing the suggestion made earlier to jam something in the compressor to take the turbine rotation out of the equation in the exhaust..while I admit at first glance it seems crazy and counter intuitive to do so, (we tend to protect that opening from foreign objects)...but I was wondering how much force is really on the turbine and if it could be held stationary without damage to the compressor wheel....???
Without hearing the sound, we are guessing, but I tend to lean toward a sound created by 1 or more, cylinder misbehaving through the exhaust valve...or a bad injector...but you replaced those...how about a weak exhaust spring? Did those get checked with the new head and I assume, new valves? Are the rockers the originals or after market? Pushrod lengths checked? Each rocker going through full valve open motion when barring over engine (cam lobes OK?)

Fievalfon 03-26-2019 02:30 PM

I’m with you guys on doing a compression check. I’ve exhausted all efforts at this point besides a compression check which I’ve been hoping and praying all along is not the coperate. To answer your question Windage, yes all new 60# springs were installed (exhaust and intake). Push rods and rocker arms are stock just modified pedastools for the install of the head studs. I have no idea about the cam lobes, a lot of work to try and examine cam lobes so I haven’t gone that far yet obviously. I do plan on try to stop the compressor wheel with a piece of wood at some point as im certain that will not damage anything but I have high doubts that is the issue any ways. Exhaust has made this noise with two different turbos including the factory HX and I’ve heard plenty of other trucks with factory HX turbos that do not make this particular sound. Anyways, as soon as I find a few things out I will let you all know. Thanks for the help to this point guys, just too bad I still haven’t figured this thing out.

windage 03-26-2019 04:11 PM

well...sounds like you eliminated weak spring. could you borrow a mag based dial micrometer and check the arc of rocker motion against each other? pain in the ass, I know...but you haven't eliminated a worn cam lobe just yet. My reasoning is; if one cylinder isn't performing like the others, it could add a wonky tone to the exhaust.. Have you run a temp gun on each exhaust outlet to compare temps?

Fievalfon 03-27-2019 12:42 AM

To be honest windage, I wouldn’t even know how to go about using a mag base micrometer to do that test even if I did know someone that had one. Lol. But yes I did do the temp gun test awhile back and from what I remember nothing seemed awry. I’ll do that test again though just to double check. At this point I’m definitely leaning towards the worst and having to assume bad rings and low compression at this point. Obviously I won’t begin a rebuild though with out first doing a compression check and confirming but gut says that’s going to be a disappointing test. The truck seems to have plenty of power and moves right along down the road but then again not quite as peppy as I’d assume a 12 valve would be with all the upgrades I’ve done.

windage 03-27-2019 08:57 AM

I follow several youtube channels with good guys that know their way around a 12 valve...DeBoss Garage and Power Driven Diesel are some of the best...imo here is a link to DeBoss;
plenty of others too. There are also several good 'leak down' test vids...good luck and keep us posted on test results..

4x4manonbroke 07-04-2019 04:07 PM

Have you done an overhead or checked the timing on you p pump yet? ... Out of time or out of spec makes some real interesting sounds....


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