View topic - Exhaust manifold job - yup broke 2 of 3 studs

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PostPosted: Wed Feb 14, 2018 1:06 am 
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Dang.
Ok I'm gonna describe my pace and beg advice / feedback along the way.
On my '23 Touring - 2 of 4 leaked at the exhaust manifold. Pop Pop Pop noisy.
I spent a week putting PB Blaster on the 3 nuts daily...
First nut came right off. Middle wouldn't budge. Aft nut seemed to move, nope it twisted off with modest effort. Dang.
So back to the middle. After a couple more days PB Blaster, I put heat on it. Unfortunately all I have is a wussy propane torch, not enough to get it red hot. (Are these nuts brass??) Did my best to heat it a few times; cooled it w spray bottle a couple times, re-heated again, it went from no-budge to POP in the blink of an eye, twisted off. Dang.
So now I have 3 studs to remove. Plenty of stud shaft left. Now I'm PB Blasting them at the block. What advice to remove them? No I'm not a welder. Vice grip? Try to wiggle? I haven't tried yet.

So removing the manifold, I tho't the air breather tube would just come out. Nope, resistance. Huh? So I removed the valve covers (for the first time) - Wow they were stuck... wow is it dirty gritty back behind them. I plan to use a little kerosene and toothbrush to clean in there. So I finally figured out the air breather tube just needed a careful jerk and out it came. Yes I saw there was a set screw on the manifold socket that it goes into, but it was long ago broken off and super rusty.

BTW my exhaust pipe is a "modern" pipe and was mounted to the manifold with hose clamps and with what appears ? to be a wrap of asbestos fabric? Its crumbling tho'.

All feedback and advice is welcome! Thanks, Texas Jim
PS I plan to get my new copper crush rings and studs from Myers.


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PostPosted: Sat Feb 17, 2018 7:04 pm 
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Here's an unexpected update. I mentioned above the valve covers were hard to get off. 1 more than the other was bent, mis-shapen. Today I cleaned them then worked on straightening the edges up; I took note that they're not identical; one is longer; one's edge is designed to overlap the other where they meet in center. I then discovered two things: they were swapped - the fore cover should have been on aft and vice versa! And, the dork PO had not overlapped the correct cover, it was backward. Gee that's why they were bent and hard to get off! When I switched them, the clearance was just fine. So obviously theyre not bilateral, or interchangable fore and aft.

QUESTION: there was no gasket on the valve covers - shouldn't I make some? Use a little permatex to stick them in place?


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PostPosted: Sat Feb 17, 2018 9:56 pm 
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There were no gaskets from new that I know of. I think Myers sells gaskets. I put them on mine and they help but still leak some.


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PostPosted: Wed Feb 21, 2018 12:52 am 
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Failures so far trying to extract broken manifold studs. These are threaded studs aren't they? A friend asked me if they were pressed studs.
On the center stud, I cut a new thread the length of the stud w a dye. I threaded on 3 nuts - the inner nut backed against the outer pair and locked them in place. I turned the inner nut but just chewed up the new threads I'd cut.
So then I tried a pipe wrench on both. Got a good bite but didn't budge. Heaved on it pretty good.
I got advice to apply heat up in the exhaust ports so to apply heat on side and from behind the stud. I did one for awhile, but I'm scared I might crack the block! So I gave up.
I hate to have to drill them out, but seems inevitable? Any advice?
Texas Jim


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PostPosted: Fri Mar 09, 2018 10:57 am 
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Update: I have successfully drilled out the middle stud - but not without much anxiety for screwing this up. Ultimate goal was not to over-bore the hole, to keep existing threads. I cut off the stud leaving mebbe 1/16 short of flush to block. Stepped up bits, the last few were 1/64 steps at a time. I took it to 20/64 (21/64 is the bit size for 3/8 tap). It was so thin I could see/feel the thread ridges. But even this thin, the remaining stud did not peel/pry away well. Still very much stuck. Used smallest punch and pick tools I had, came out in threads. I managed to get about 2 turns from the front clean - then carefully threaded a 3/8 tap. Made certain I was in original thread groove - then the tap cut the rest of old stud out. I used a magnet on a punch shaft to collect all the shavings. So it looks great but I don't want to repeat it on my other stuck stud. I'm searching for a mobile welder, to apply serious heat etc.


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PostPosted: Mon Mar 26, 2018 10:25 pm 
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Update on 2nd stud: I tried hard but couldn't find anybody with mobile acetylene to help me. Multiple good advice I got was "heat it good and red" let it cool, do it a couple times, while hot rap with hammer, then hit it with penetrant (one friend swore by the candle wax method). So I attempted with propane, but I never gained anything. Not even a pipe wrench would budge the stud.
So I did it the hard way - again - I cut it off and drilled it out. Success. Go SLOW, getting it centered is essential.

Ok I learned something. I didn't know what a bottoming tap was. Didn't have one. I'd only ever worked with tapered taps. Wow - ! A friend 'splained to me the bottoming tap allows near entire depth of the hole to be cut - what a huge difference. I almost feel like ol' John and Horace themselves with my newfound machine knowledge - HA nope


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PostPosted: Fri Apr 13, 2018 5:16 pm 
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Texas Jim here closing on this successful repair. Successful but not without the anxiety described above, drilling out the old studs. Because of the drill out, the "new" stud sockets weren't perfectly aligned perpendicular to the old sockets. After inserting the one stud, one was mal aligned a few degrees, enough that I couldn't just slide the manifold back on. So I ended up overboring the 3 manifold mount holes, up a 16th. Doing so created enough space to re-mount.
I installed the new crush rings (from Myers) dry. The first trial run running the engine I had a fair amount of leak - but I torqued gently and while HOT, and eliminated visible leaks. I was nervous about over torquing, and breaking off the manifold ears with the holes... but no trouble. Telling an old timer friend, he advised I could have used a copper-infused sealant to coat the crush rings and prevent leaks? But so far so good.

OK one more thing - My exhaust pipe is a modern type, I do not have an exhaust collar. It was mounted with a crude packing held in place with a hose clamp. I think it was a 1 7/8 OD so it left a fair gap around the sides. So I bought an exhaust sealant product described for patching holes in mufflers, pipes etc. It goes on very wet/slimy, and hardens to a ceramic glaze. I sealed the pipe into the manifold, pushing it like you'd pack a wheel bearing. Its a winner - hardened and no hint of leak.


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