12 valve with a terrible fluttering paper bag sound from exhaust. HELP!!!
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#44
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?)
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?)
#45
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.
#46
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 ***, 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?
#47
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.
#48
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..
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09-04-2013 07:15 PM