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?
Highest post turbo egts bobtailing
Discussion in 'Trucks [ Eighteen Wheelers ]' started by LameMule, Aug 14, 2020.
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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 -
magoo68 and Brettj3876 Thank this.
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seams alittle warm for bobtail
650cat425 and Brettj3876 Thank this. -
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650cat425 Thanks this.
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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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650cat425 Thanks this.
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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!650cat425 Thanks this.
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