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Exhaust manifold woes

Old May 12th, 2019, 7:11 PM
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Default Exhaust manifold woes

Hello everyone, new to the forum and really need some good advice. On my 94 K1500 350, all 6 exhaust bolts are broken and or rusted off at the manifold flanges. Being without torches or welders, I tried to hire a couple local mechanics to extract the bolts. Nobody was thrilled to take the job, and both suggested I buy new manifolds and install them myself at a similar cost. "Just run the motor until operating temp and the bolts will come right out" they said. Sounds easy enough...
Wrong. The very first one snapped off with hardly any pressure applied. I couldn't believe how easy it spun, until I realized it wasn't unscrewing at all. Had I encountered some resistance, I likely would've considered paying to have them put on. Anyhow, now I still have 6 flange bolts welded in by rust, and now one snapped in the head. The truck isn't worth a huge mechanic bill, so the question is now what? Could I possibly prevent the manifold from leaking now where the bolt broke? And then *ugh* drill the flanges out from underneath? I feel like removing the manifolds now is going to open a can of worms that I simply can't recover from. Any and all advice would be greatly appreciated... thanks
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Old May 13th, 2019, 1:59 AM
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i dont really think ive ever had a manifold bolt/nut come out without snapping. even when changing engine or something we plan to break them off right at the start that way you dont get all pissed about breaking one. im sure you can drill and tap it from the bottom but there would be too much to work around and not to mention the flange being in the way. looks like for a little over a hundred you can buy new manifolds. the head bolts for the manifolds are a little different you dont want to break them so try to lube them up real good with PB blaster or something
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Old May 13th, 2019, 1:22 PM
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[QUOTE=Irish_alley;427920]i dont really think ive ever had a manifold bolt/nut come out without snapping. even when changing engine or something we plan to break them off right at the start that way you dont get all pissed about breaking one. im sure you can drill and tap it from the bottom but there would be too much to work around and not to mention the flange being in the way. looks like for a little over a hundred you can buy new manifolds. the head bolts for the manifolds are a little different you dont want to break them so try to lube them up real good with PB blaster or something
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Old May 13th, 2019, 1:44 PM
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Thank you for the response. If i wasn't clear, I have purchased new manifolds. I soaked the old bolts with PB blaster for a few days until they arrived. I then started the truck and ran it up to operating temperature per the mechanics instructions. I then started to remove the old manifold on the passenger side, and immediately broke the first bolt. It fell out easy, as if it were ready to fall out soon before I even touched it. So I feel more will break as well.
The mechanic originally said he would do both for around $200 labor. I'm afraid of the dreaded phone call to inform me I owe a lot more now due to broken bolts. Let's say the new price is $600 for example, it's not worth it for a $1000 truck.

I guess I've never had good luck with mechanics, the bill never seems to line up with the estimate. When the call comes in that the manifolds are off, and I now have to pay to remove 4 broken bolts from the head, I'll be without options. I'm not experienced enough to start tampering with the head. And then my truck will be without manifolds, and in a non working condition. Should I assume removing broken bolts from the head should be an easy job for an experienced mechanic? I realize problems come up, but I'm at the mercy of whatever they tell me then. I feel like I should leave them alone now, and hope I don't develop a nasty leak where that bolt came out. Or perhaps I'm over thinking this, and the mechanic is fully prepared for that scenario and has included that in the $200 estimate. I'm honestly afraid to ask, because I feel like they are always gouging me and running up my bill. No offense to any mechanics reading this, but a good reliable and honest one seems hard to find...
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Old May 13th, 2019, 2:27 PM
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Here's a question. In this truck, (94 k1500 silverado 5.7 350), is there a manifold bolt that could break which would require a head to be removed? Or are they all accessible in some fashion?
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Old May 14th, 2019, 2:29 PM
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they should all be accessible in some fashion. if the head breaks off or part of the bolt is still sticking out that makes it much easier to take out. most times what happens is the bolt will rust to the manifold and be seized in the manifold. if you still have some of the stud sticking out then you can try to grab it with vise grips once the manifold is removed. you can also weld a nut onto the stud (if you have a welder) once again when the manifold is removed and try to unbolt it again
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Old May 15th, 2019, 8:00 PM
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Okay. I'm trying to find out if the mechanic is going to do the work or not. Any advice if I get stuck doing it myself? I've been spraying PB on the bolts every day. But I don't have any torch or welder. Closest thing I have is a propane torch. Should I try to heat the bolts? or manifold? or both? Or is running the motor to heat things up the best way, as the mechanics originally suggested?
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Old May 15th, 2019, 10:21 PM
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mig welding is the only way to fix this...do not drill. Anyone who wants to drill it...go elsewhere...they will either wreck the head or charge huge labour times.
when the bolt is broken flush....place a nut over the bore...weld thru the nut onto the broken bolt and fill it to join the bolt and nut...turn the nut out with a wrench.

disconnect the battery b4 you weld.
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Old May 16th, 2019, 1:35 PM
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ive always thought if you heated the bolt it will cause it to expand into the manifold and head, but i had a guy who i trust explain to me
"The bolt will melt before that happens. With heat dissipation and different thermal expansion rates, the two dissimilar metals once again become two separate entities. The intense heat helps make coarse material become fluid so that the threads can once again operate and that is why you heat the bolt."
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Old May 17th, 2019, 10:48 AM
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So all I I have is a basic propane torch, do you think that would get them hot enough? I don't know how hot they get by running the engine. I could get Mapp gas, burns slightly hotter than propane.
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