Remove exhaust manifolds with engine in?

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Dunk67
Posts: 109
Joined: Sat Jun 19, 2021 4:53 pm
Location: NJ

Remove exhaust manifolds with engine in?

Post by Dunk67 »

Working on a 66 that head a badly leaking exhaust riser valve. Got a solid spacer to replace it but managed to break one of the exhaust studs in the manifold. I have a spare pair that I blasted and painted some time ago, ready to install. Exhaust manifolds bolts on the top are all very crusty and no room for a ratchet, 9/16 socket fits anywhere from loose to spinning on the top four bolts.

Should I even try to do this with the engine in? Or will I round or snap one of the exposed top bolts and be pulling the heads or engine anyway? only pull the heads and freshen up the top end while heads are off? Or pull the whole engine and just do whatever it needs? It runs well great and starts easy, a little smokey on cold start but clears up when warm. No idea if it's valve guides/seals or rings. I was hoping to get all the leaks fixed (trans, steering), suspension/steering/driveline freshened up and just drop it off for paint. I'm thinking this has turned into a can of worms, down the rabbit hole... What would you guys recommend?
David Langhorne
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Re: Remove exhaust manifolds with engine in?

Post by David Langhorne »

If you have access to oxy acetylene equipment I would heat up the "ears" and the screws should come out. You may find a metric wrench will fit with a little persuasion or else some vice grips. Remove the screws from the engine mounts and jack the engine up a couple inches to get access. I only broke one off when I did mine and rather than get the head off to remove the remains of it I put a clamp over it. The bottom ones always come out no trouble from underneath. I used stainless screws to replace. I wouldn't use too much force but try to tighten/untighten alternatively. I never found releasing fluid made the slightest difference - heat is what you need. Good luck,
Dave Langhorne 65SL
UK
RAVEN
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Re: Remove exhaust manifolds with engine in?

Post by RAVEN »

AND the old melt a candle trick helps. For some reason the wax will creep into the bolt interface and allow easier release.
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sleeper bird
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Re: Remove exhaust manifolds with engine in?

Post by sleeper bird »

2nd on the heat iv been there before,iv never had good luck with a ratchet iv always used a box end wrench on the top.
Dunk67
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Re: Remove exhaust manifolds with engine in?

Post by Dunk67 »

I've had a couple days of heat and PB blaster on the four upper bolts. I did finally get one head to budge, but it feels like it's twisting the bolt and the threads aren't moving. Going super easy on them with a 14mm six point wrench, and when hot and soaking in PB I tap the heads with a hammer and punch to try to get the PB deeper in the threads. I won't throw in the towel and pull the engine until I break one, but I think that's where this will end up.

I have not tried wax yet but I'll give it a shot. I only have a MAPP turbo torch so I can only gear things so hot. I finally got around to trying the bottom bolts, two came out no problem, haven't tried the other two but I'm sure they'll be fine.

Some pictures, because who doesn't like seeing a crusty engine that looks like every other crusty 390...
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jtschug
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Re: Remove exhaust manifolds with engine in?

Post by jtschug »

14mm? Aren't they an SAE size?

You may need the oxy-acetylene torch to heat those ears up. Breaking one of those bolts off will make this a much bigger job.
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
RAVEN
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Re: Remove exhaust manifolds with engine in?

Post by RAVEN »

A MAPP torch is probably ok for the wax trick. You do not want to get things to hot or the wax will just burn off.
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David Langhorne
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Re: Remove exhaust manifolds with engine in?

Post by David Langhorne »

Definitely needs oxy-acetylene to heat ears to red heat. I paid equivalent of $50 to get my exhaust manifold studs removed as I didn't want to risk shearing them off near the flange.
Dave Langhorne 65SL
UK
David Langhorne
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Re: Remove exhaust manifolds with engine in?

Post by David Langhorne »

jtschug - yes they are SAE but if the heads are slightly worn then a 14mm will be snugger fit on a 13/16 - in fact it is a better fit on my s/steel manifold bolts which are obviously not corroded at all.
Dave Langhorne 65SL
UK
David Langhorne
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Re: Remove exhaust manifolds with engine in?

Post by David Langhorne »

Sorry not sure what size the manifold bolts are - think maybe 9/16 but I found a metric wrench fitted best..
Dave Langhorne 65SL
UK
sleeper bird
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Re: Remove exhaust manifolds with engine in?

Post by sleeper bird »

i tried map gas not good enough,had to get a small acetylene rig and get the ears glowing, some i had to let cool and go back and try again i got all of them out.id chase the threads with a tap if you get them out.
Dunk67
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Re: Remove exhaust manifolds with engine in?

Post by Dunk67 »

Indeed 14mm is slightly smaller than 9/16", which gave a tighter fit on what remained of the heads.

I carried on with MAPP gas and PB, and also picked up some CRC Freeze-Off, which I never tried but is a penetrant that is supposed to cool the fastener as you spray for an extended time. I did some cycles with that heating for a minute or few then spraying the fastener head and threaded hole in the head with it, along with more PB. Two of the top bolts came out fairly easy after enough time with heat and soaking. One started to move, broke after more cycles, but I was able to extract. One broke off flush in the head, it is the one that holds the lift ring and the bolt protruded through the threaded hole in the head. From the start I was fairly certain this one would not come out since it looks solid and there is no recess for penetrant to pool and soak in.

So here I am with one bolt broken in the head close to the shock tower and little access. What now?
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Rt.146
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Re: Remove exhaust manifolds with engine in?

Post by Rt.146 »

It is the angle of your socket that makes it difficult or near impossible to remove the bolts while the engine is in, without breaking a few. I done them without breaking a single one, with the engine out, where I could achieve a better grip of the bolt. Well, lucky me on that one.
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Jim Wulf
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Re: Remove exhaust manifolds with engine in?

Post by Jim Wulf »

Dunk67 wrote: Sat Dec 18, 2021 9:04 pm Indeed 14mm is slightly smaller than 9/16", which gave a tighter fit on what remained of the heads.

I carried on with MAPP gas and PB, and also picked up some CRC Freeze-Off, which I never tried but is a penetrant that is supposed to cool the fastener as you spray for an extended time. I did some cycles with that heating for a minute or few then spraying the fastener head and threaded hole in the head with it, along with more PB. Two of the top bolts came out fairly easy after enough time with heat and soaking. One started to move, broke after more cycles, but I was able to extract. One broke off flush in the head, it is the one that holds the lift ring and the bolt protruded through the threaded hole in the head. From the start I was fairly certain this one would not come out since it looks solid and there is no recess for penetrant to pool and soak in.

So here I am with one bolt broken in the head close to the shock tower and little access. What now?

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Just take the engine out, you'll be glad you did. Besides, I don't think you have much choice considering the circumstances. It's really not that difficult, especially since there's no AC to contend with. It's one of those jobs where you'll look back on it and say to yourself, "Now why didn't I just do that in the first place?" I find it easiest to leave the transmission attached, others don't. It's your call. Look at the attached link.

http://www.tbirdgarage.com/Site_2/Techn ... al.html#23
Jim W, VTCI 1961-1963 Technical Editor
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David Langhorne
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Re: Remove exhaust manifolds with engine in?

Post by David Langhorne »

If you only have one bolt broken off like I did you could put a clamp on it either permanently or temporarily. If you haven't the equipment or anyone to help this will work. I did mine over 15 years ago and made a clamp from an old tire iron. I have attached a pic
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Dave Langhorne 65SL
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