Highest post turbo egts bobtailing

Discussion in 'Trucks [ Eighteen Wheelers ]' started by LameMule, Aug 14, 2020.

  1. LameMule

    LameMule Light Load Member

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    Interested to hear what you guys are seeing for max egts while bobtailing and how that correlates to loaded egts. I've been working on a 7fb 3406b with an Or6169 turbo and trying to get it ready to go to work hauling no more than 80k. I've taken the intercooler, piping, boots and clamps off cleaned inspected and reassembled. I ran the overhead and I installed a new afr diaphragm and o-rings. I pinned the pump and set the timing at half a hole on the flywheel. The engine starts and runs great. I have only bobtailed it so far and can get roughly 17psi boost but I'm also able to get up to 900* egt measured post turbo. I am sustaining 850* egt on a mile long 6% hill bobtailing. It idles at 300* egt and seems to run well. I'm just trying to get my ducks in a row before I hook up to a trailer and get stuck at the bottom of a hill because it builds too much heat to stay in the throttle. I've never touched the fuel screws in the pump but the afr was backed nearly all the way out with just a thread showing so guaranteed the fuel's been turned up.
    I'm looking for guidance from guys with more experience. Are my egts too high for being empty? What are your empty and loaded egts?
     
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  3. Brettj3876

    Brettj3876 Road Train Member

    Empty wagon i push 950-975 if i keep my foot in it on a pull. Same pull loaded 1000-1025 roughly. Won't go any higher than that. 1000 in short bursts won't hurt a thing.

    93 says 1025 max and the 99 says 1100. Both E-7 macks
     
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  4. LameMule

    LameMule Light Load Member

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    Thanks for the info! The funny thing is I've rarely paid much attention to the pyrometer while empty and typically I was driving a much newer and known dependable rig. I recently bought this old 359 peterbilt and I just want to get all the bugs worked out before it goes to work.
     
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  5. little cat 500

    little cat 500 Road Train Member

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    seams alittle warm for bobtail
     
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  6. 062

    062 Road Train Member

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  7. LameMule

    LameMule Light Load Member

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    That's what I'm thinking. I'm probably going to be fixing a headgasket and liner issue. I'm getting oil and air bubbles in my coolant.
     
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  8. wore out

    wore out Numbered Classic

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    You better pin time it or your gonna be buying some pistons. 7fb are 24 or 21 degrees static depending on the pump cam. That's plenty
     
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  9. LameMule

    LameMule Light Load Member

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    Thanks for the advice!
     
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  10. bad-luck

    bad-luck Road Train Member

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    I was thinking the same thing
     
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  11. LameMule

    LameMule Light Load Member

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    Pulled the head off today and it appears that there's a cracked piston in the #2 hole. Looks like the fire ring gave out on #2 as well. There's still pretty good cross etching from the last rebuild (unknown time). There's some very small cracks in #3 that are only visible with a shot of brake clean. I'm assuming the rest of the pistons have damage as well.
    Do you guys have any advice on what to look for or what plan of action to take?
    I'm hoping that I could just do new seals on the liners and 6 pistons with a gasket kit. Should I just get new liners? Any advice is appreciated!
     
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