1999 12.7L detroit repair

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by City-Boy, Dec 2, 2023.

  1. City-Boy

    City-Boy Light Load Member

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    May 20, 2017
    Deep south BAMA
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    Hoping someone may be able to spread some kind of knowledge for me!
    Took my classic in for major oil leak it was front gear cover turns out it was crack so they replaced the 2pc cover with new front main seals. They called back and apparently it was still leaking they were vague on details but I guess a oil return port sooo they say it's the cylinder gasket so suggest upper seal kit and it will be done Thursday but they'd keep it over night to make sure everything was good!! I finally had to call them Friday at 2pm and they owner seemed extremely frustrated and only said there was a "hiccup" and they were replacing the gasket again and he'd call back... but the call never came soooo I'm obviously not mechanically savvy which is why I took it to a reputable engine builder in the first place so I guess I'm just sitting here stumped to what would be the "hiccup" why would they be redoing the job? If it was something wrong with my block or head he'd have called immediately telling me I had to spend more money so what could they have done? What could go wrong? It's an old engine but he said several different times it was running great and didn't recommend an overhaul at this time so yeah what the hell could have went so wrong that he's frustrated and not informing me on what's happening? Maybe I'm just freaking out but it seemed like something major
     
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  3. Smellfunny

    Smellfunny Road Train Member

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    If they took off both gear cases then they could have got it out of time. If the cylinder head gasket was not leaking before it should not have started leaking if they did the gear case covers. The cam plate or perimeter seal would be a possible leak from doing the gear case. I think I would go there and see what is going on first hand ASAP. If they got it more than one tooth off of timing it would go bad quick. 1 tooth will get you about 900 miles before bad times. The only other thing I can think of off hand would be if they left the camshaft bolt loose.
     
  4. JB7

    JB7 Medium Load Member

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    "and not informing me on what's happening" He did inform you telling you there was a hiccup and they were replacing the gasket again. Translated to mean we screwed up, the front cover is a lot of work and labor hours and I have to eat it. So is the head gasket but not sure which he was referring to.

    "They called back and apparently it was still leaking they were vague on details" Meaning they were not thorough in diagnosis and/or screwed up.
    I would show up in person on Monday and see the truck for yourself and ask the owner about the status.

    Maybe I'm just freaking out (yes, true) but it seemed like something major. Whatever happened it is on them to correct.
     
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  5. Rideandrepair

    Rideandrepair Road Train Member

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    Yeah, go in and look at the Truck. See what they’re doing. Those covers are very expensive new. Over $2000 each if I remember correctly. All that Labor, usually 20 hrs., now would be the the time to replace bull gear if its age is unknown. What’s another $1200? There’s at least 1 o ring in there they may have missed. Diamond seal may be messed up. It’s near the front of the head, sits on backside of the top gear, bolts to the cam bracket. They use anerobic sealer between block and covers. It looks like red vasoline. Doesn’t dry unless it’s airtight. You should see it all around the seems of both covers. It wipes off easily, won’t dry. That’s normal. Maybe they missed an area between covers. Could be a lot of things. It’s a big job. involving removing all the gears to get the inside cover off. You only want to do that job once every million miles or more. Show me the old cover and where it’s cracked too. Be polite, but ask questions. It’s your Truck.
     
    Last edited: Dec 2, 2023
  6. Rideandrepair

    Rideandrepair Road Train Member

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    Look up Joe Gingrich Series 60 bull gear on YouTube. There’s a bunch of videos on rebuilding your engine. The can installation video also. You can get an idea of what’s involved. Great videos on your engine. Get familiar with it, not as hard to understand as it seems. Having some knowledge will help a lot, when dealing with Shops. I hope they’re not trying to make you pay for their mistake. Get some info, give them the benefit of a doubt. Please give an update. I’m interested in what they do. Same Truck, same engine. currently the head needs to come off. Trying to avoid any pitfalls.
     
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  7. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    If there was still a leak, several things. There's an o ring on an oil galley between the block and front structure. There's also an o ring in the center of the bull gear hub. I've seen both forgotten before. The o ring on the bull gear hub leaks around the center of the front cover, the o ring between the block and front structure leaks on the backside of the structure, and looks like a head gasket or cam seal leak.

    There's also o rings under the front and rear cam cap, and o ring washers under the front and rear rocker arm studs.

    Without knowing where it's leaking, it's just a guess.

    BTW, Screw that guy for getting annoyed you called. Unless you've been naggin at them. This is your truck. You're the customer.
     
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  8. Smellfunny

    Smellfunny Road Train Member

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    I have also seen hairline cracks right where that little o-ring is on the back of the gear case cover that mounts to the block. I did one once and told my dad I thought it was a crack and he said it was not so I put it back together. It was a crack. SO I had to tear it back down.
     
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  9. City-Boy

    City-Boy Light Load Member

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    Cover had cracks that was verified by freightliner that week but their cost was just to high and wanted almost 10 grand down to even order parts then again verified by the shop it ended up at to finally be fixed!
     
  10. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Did you tear that one down for an oil leak? I've seen the same too many times.
     
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  11. City-Boy

    City-Boy Light Load Member

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    Mine was leaking visibly from both sides and bull gear cover was terrible so I'm assuming they had the cracks correct especially from two different shops. I'm confused also on why that would start leaking after the cover fix he suggested once it was sealed up it exposed that leak so I honestly am lost but I'll update soon as I learn something
     
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