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Hydro Lock PSA

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Tim McKay, May 29, 2020.

  1. Tim McKay

    Tim McKay Registered User

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    This is a Public Service Announcement to hopefully help others so this doesnt happen to you.
    I had installed a new body to hood gasket at the back if the hood, as I read on here about hydro lock and damaging engines. It seemed a little obscure to me, so I didnt worry too much about it. We had a ton of rain here in Atlanta in the spring, and I am sure this failure was due to water intrusion from rain sitting on top of the air breather, ( its a NA truck ). Make sure your grommet seal on the center of your air breather will hold any errant water out. Better yet, maybe modify the hood seal so water with drain further to the sides of the engine, or adapt another seal design.
    Unfortunately this engine was in fine shape. 156k miles, ran like a top, no smoke what so ever, and it got high gas milage. When we tore down the engine, everything was in excellent shape except #8 rod.
    Take heed, it can happen to you.

    upload_2020-5-29_7-54-23.jpeg

    The good news is its an IDIT now.
     
  2. Kizer

    Kizer Supporting Member Supporting Member

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    Man, I'm sorry that happened...not as sorry as you are.

    Happened to me too.

    The good news out of my disaster: I found this forum.

    It's funny to think back, the interwebs were very new (to me) then.

    What turbo set-up did you go with?
     
  3. Tim McKay

    Tim McKay Registered User

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    I got a factory reman (Motorcraft) IDIT with the factory turbo. It was in the back of a wharehouse, and forgot about. Got lucky.
    I hate it happened to you too, maybe more will heed the warning seeing our combined postings. I wonder over the years how many succumbed to this.
    This forum, and Wes (cant thank him enough) have significantly accelerated my learning curve on these diesels, as this was my first.
    Just trying to give back a little, and save others from this plight.
     
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  4. nelstomlinson

    nelstomlinson Full Access Member

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    That looks exactly like the #8 rod I pulled out of the junk yard engine I'm rebuilding. It was a good engine with little wear other than that graceful curve and some rust pitting in that cylinder.
     
  5. Golden Helmet

    Golden Helmet Full Access Member

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    If you put a new seal on, make sure you test it with a bottle of water. I heeded the warnings here and replaced my cowl seal before it started leaking, but the new one didn't fit quite right and it leaked like a sieve. I had to use a RTV to get the new cowl seal to stop leaking.
     
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  6. Kizer

    Kizer Supporting Member Supporting Member

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    Nice.

    Should you run across another one, please reach out to me!!
    I have two good trucks in need of a transplant
     
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  7. Macrobb

    Macrobb Full Access Member

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    So how did it run like that? I'm guessing that with the rod still intact(if bent) it'd still run... but perhaps have a dead cylinder?
     
  8. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    My hydrolock horror story, short version: Fresh rebuilt 6.9 with less than 1,000 miles on it. I’m out of state for a few months. Tell son to start it and let it warm up every week or two. Wife calls, says truck just blew up. Big Bang, all of the coolant on the ground, parts on the ground. Get home a few weeks later and found 3 freeze plugs and a piece of the head gasket on the ground. It blew the head gasket so violently that a chunk of the rear corner of the gasket about 2” long was on the ground WITH ARP head studs! On tear down found #8 rod bent, cylinder bore rusty. Cowl seal was in poor shape....
     
  9. pafixitman

    pafixitman Registered User

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    Yep - piss poor design on NA motors.

    I caught mine before I tried to start it. It was winter and I had ice in the intake. Vacuumed out the water and pulled out ice chunks, drained the oil (2 qts of water), pulled the GP and did the ATF / MM oil soak and slowly barred her over a little at a time and repeated the soak. She slowly spit up any additional water.

    I have the Banks lid so it was able to hold water and slowly fill the cylinders!
     
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  10. Enginerd

    Enginerd Full Access Member

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    I found the same advice on this forum and changed mine too when I first got the truck.
    I've been up in the woods a lot lately with the truck, and didn't realize I had a little stick jammed in the seal right over the intake. We've had a ton of rain here in Arkansas, and I went to start my truck up the other morning... One rotation and it hit that cylinder full of water. I suddenly realized what happened, opened the hood to find the intake lid holding water and that little stick sitting in the seal.
    I figured what damage could be done has already been done, so I went back and cranked the starter on that cylinder a few times. To my surprise it coughed all that water and a ball of soot all into the dirt (still impregnated two weeks later into the ground!) and fired up. No issues, but I'm lucky! It did clean my exhaust out though :D

    0601201045a.jpg
     
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  11. Tim McKay

    Tim McKay Registered User

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    it didnt run, The failure mode was it locked up.
    Im hypothesizing that maybe it had minor hydro lock earlier, mayBe with less rod bend. I say this because the upper rod bearing has a distinctive wide even wear pattern across the width of the bearing, indicative of a high load. The bottom bearing on rod looks perfect, even wear.
    This is based on experience I have with a particular small displacement 4 cylinder that was designed with a weak crank, and it can load a bearing in one zone at high RPMs.
    I dont claim to be an expert, but I am not a rookie either.
     
  12. Tim McKay

    Tim McKay Registered User

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    Damn, thats way worse! New engine, and it blew apart! Sorry to hear.
     
  13. Tim McKay

    Tim McKay Registered User

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    you should have bought a lottery ticker that day!
     
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