Hi I just finished doing my injectors and adjusted my valves to .012 and upon the test drive I got on it and a boost tube clamp was loose and it blew off...... no biggie right? well now I have a popping sound that is reonating through the boost tubes. Like a hollow ba ba ba sound. Did a balance test . all squirters were within +/- .4 so that's good. When we tried a cylinder contribution test they were all good and even until it got to #8 then the snap on scsnner went into error mode...2-3 times in a row. whts up with this? Some how I think I lost an intake valve. was perfect before the boost thing happened. guess ill pull ff the dr side again and see wtf happened. have a feeling im doing the heads.any help appreciated
boost tube failure ..... bad valve now?
- Thread starter nwodiesel
- Start date
If you have a valve problem, it should show something on the balance rates. Balance rates don't really show anything about the injectors. They show how much the computer is compensating to even out the cylinders by adding or removing fuel with the injectors. If you have a valve that is hung open or damaged and not sealing, there should be a high + balance rate on that cylinder. I would run a compression test before I started pulling the motor back apart.
Did you tear or get a small hole in the boot or boost tube when it blew off. Just something to double check.
That' how a diesel sounds with no turbo.. turbo muffles that sound. Put the tube back on and drive. If it still sounds bad then re check your valves. When i did my head gaskets 2.5 years ago i left #2 cylinder exhaust valve lash nut loose so on start up it was fine then after about 10 minutes of idling it started popping really loud out of exhaust and intake. Pulled valve cover and saw the exhaust valve had loosened up all the way.
ya they were all in balance. +/- .4. When we did a cylinder contribution test it showed all wer good till it hit #8 then it errors out. 3 times it went thru the motions...shutting down one hole at atime but still stall at #7.... but shows a error message for #8. Terrified after all that I have to take off heads
boy I was sweating doing the injectors but now that ive done them..... id take that over a valve repair. Hope u r right. gives a small light at the end of the tunnel.hope its something easy. It didn't make noise till the tube come off .... unless it was coincidence but my hindsight says no
I wish. Its a loud sound ..... sounds like a have a private drummer under the hood keeping pace with thr rpm lol
Have you tried shutting the cylinders down one at time with the scanner rather than doing the contribution test? This sounds a lot like a 4500 I dealt with. Ended up one of the bridges had popped off. Balance rates weren't bad at all.
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well,the contrib test with the snap on scanner shuts them down one at atime to determine the individual contribution. when it got to #7 it went into error mode on the scanner... but says "error 8,,,, a few times. so its either #7 or #8.... but my buddy says iy may be shutting a different cylinder down to load up the one its testing. im frustrated. $3500 and countless hrs learning and im worse off. Least I knew the injectors are good now. Had a feeling when I buttoned it up it wouldn't be the last time in there..... but not the same day!
btw what "bridge are you talking about". first duramax
I'm honestly a little confused about the contribution test as I don't recall ever seeing that option for a dmax in my old red brick or my solus.
Try shutting off #8 and 7 manually and see what it does.
The bridge is the little guy the rocker pushes on that spans 2 valve tips. Maybe my vernacular is off.
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I thought that's what umeant. I did adjust all the valves while the covers were off... to .012'. one of them was tight.... back valve on the drivers side (#8). No matter how many times I rolled it over or what position the crank was in I couldn't get a feeler into it. hmmmmm.maybe it had a seat issue already and it was just coincidence.... oddly enuff that's an intake valve too
btw how do I shut them off.. with the scanner u mean?.
Which snappy scanner do you have? IF my memory serves me its under functional tests or output controls. You are using the correct software and not global correct?
If the truck is not skipping, and its popping out the intake, chances are you have a pair of exhaust valves not opening. Feel free to take what I'm telling you with a grain of salt, compared to alot of the folks on this particular forum I'm a noob, and I've only seen what I'm describing once.
Its abuddy who runs a shop and keeps paying the updates so im sure its current.the exhaust valve thing makes sense. im tearing down again right now. gonna start on the drivers side as that's the valve that was too tight when I adjusted them. couldn't get a feeler in to it no matter where the crank was.then I undid the lock...backed locknut it off till it was loose at set it at 012. snappy says its an error #8. cant or wont even finish the contribution test. im hoping a bridge fell off or ???? damn im frustrated.....what could have happened?it was immediately there after the boost tube come off....and it was building boost pretty good when it let go. Im thinking it has something to do with that.Ran for an hr mint last night
I would shut the cylinders down one at a time to see if shutting down one cylinder quiets it up. That will tell you which valve cover to pull. I wouldn't just start tearing it down. Although it sounds like you have some shenanigans going on cylinder number 8 and you know it.
Youre right..... one of the lock nuts for the valve adjustment had backed off all the way. One thread left holding it. Could have been worse for sure. Know what a non functioning pair of exhaust valves sound like now haha.Thanks for the tip