Exhaust putting out excessive moisture

Discussion in 'GM Diesel & DuraMax' started by Dirty Dog, Mar 24, 2012.

  1. Dirty Dog

    Dirty Dog Member 2 Years 500 Posts ROTM Winner

    Hey all not sure if anyone has noticed this with their duramax, but my 07 LLY seems to be expelling what i consider to be an excessive amount of moisture from the stacks, I fired up a few trucks around here yesterday and let them run till normal engine temps then drove them around a bit, and did the same test runs with the top kick, and found that my observations are correct, ,,,
    now if your wondering why this concerns me while that is simple, as you can see from my pics i am fairly annal retentive about the cleanliness of the dirty dog, and Polishing exhaust/rust stained water runs and marks off of 57" chrome duel stacks really sucks.... I have read in some other posts about this problem but no one had the cure.
    It seems to be only on the duramax, the inter smash ups and cummins are a lot older, and there are some stains showing on the stacks, but nothing like the topkick.. I am going to look at the lowest section of the exhaust today to see if i can drill a small 1/4 vent hole, but i am not sure this will cure my drippy exhaust blues, as the moisture seems at its worst when the truck is working, I don't think its a build up from idling....
    Any help or suggestions on this would be greatly appreciated...
  2. Blazer454

    Blazer454 Member

    sounds like a possible internal coolant leak, i would check for that. if its got an internal coolant leak and is burning the coolant its going to have moisture out the exhaust and show more when the truck is hot and working. I would check for that.
  3. Dirty Dog

    Dirty Dog Member 2 Years 500 Posts ROTM Winner

    Thanx Blazer, for your reply

    Its a good thought the coolant thing, but no smell of brunt coolant, 2 years not a drop of coolant has been lost, when I first got the truck from the dealer I found a lose rear heater hose clamp on the return line but other then that I have never had to add any coolant.........

    This Moisture is a clean wetness, that before i put the stacks on ran off the mufflers tail pipe and actually left a small puddle or ice patch in the winter beneath my truck. A very clean smell less almost looks like filtered water good enough to drink... lol maybe a very expensive Britta filter .... the rust and exhaust colours and residue i have to clean off is most defiantly coming from the inside of new stacks, and I am hoping that once i have a few more hours on them they will weather and the issue will settle down

    I am fairly confident that is nothing more then a duramax issue, and one i most likely will have to live with. I will be doing a cat delete update in the future, and personally suspect the cat as the culprit and this may indeed fix the problem, until then i think a small hole after the flex pipe, and before the chrome Y pipe, this being the lowest area of the system, will relieve most of this extra moisture from idling and warm up.

    I will be doing that this weekend and keep you all updated on my success or struggles with this issue,,, until then its just a little more detailing then i am use too... But they do look real sweet all spit polished
  4. Blazer454

    Blazer454 Member

    So it sounds like just normal eshaust moisture then. Every vehicle builds up moisture in the exhaust system which is why factory mufflers have the small hole in them for the water to drain out. I think your idea of drilling that hole would be good and hopefully it will take care of your problem. Cant wait to hear if it helps. Good Luck
  5. Dirty Dog

    Dirty Dog Member 2 Years 500 Posts ROTM Winner

    Ok I went to the city yesterday for B&E and coffee with my best friend yesterday, I drove the truck a break neck on the way to the city, then let it idle well we ate and chatted about an hour or so. and when we returned to the truck i revved her up and sloooosh splat .......... so we have determined that the excessive moisture is coming from the the idling time, when there is not enough exhaust pressure to move the vapour out of the 5 inch stacks(60+height). so our technical savvy concieved from a monday morning breakfast, is to drill a small drain hole in the 90 elbow below the chrome Y pipe..... so I will clean the stacks today and drill this drain hole. and try again, with exactly the same test, hard drive to the city, and then bacon, eggs, toast and hash browns... ohh the tests we come up with here.....they are fun and fulfilling....
  6. Blazer454

    Blazer454 Member

    That sounds like a good test. I just got very hungry. It does make sense that while idling that moisture just isnt being pushed out with the exhaust so it build up at the lowest point. DO WORK! and drill that hole :great:
  7. Dirty Dog

    Dirty Dog Member 2 Years 500 Posts ROTM Winner

    yeps it seemed to alleviate the build up all though we only have tested in the yards far,,, defiantly draining some clean clear liquid drops, I believe the rust is just off the new stacks, i guess chroming the inside would be costly.... once they oxidize the rusty slime should be gone as well.....haven't decided how big the hole should be yet started at 1/4 .... it was sorta funny the hole worked out to be in the exact spot of the stock tail pipe......
    will most likely have to clean them a few more times in the next few miles, but thats ok:money:
  8. Blazer454

    Blazer454 Member

    at least its working so far. Hopefully it will solve your problem
  9. Sierraowner5.3

    Sierraowner5.3 Epic Member 5+ Years 1000 Posts

    if it makes you feel better, the exhaust on my truck (gasser, i know) does almost the same thing, due to the style tips i have, water drips off them and discolors the ends. idling time and short trips is whats getting me. there are even holes in them, i widened them out slightly, and that seems to be helping, but still annoying.

    unfortunitly, my truck dosnt get run hard enough, often enough. to much slow poke driving on post, not enough 50+ mph for a while.


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