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Exhaust Manifold
#1
Hey guys,
One of my exhaust manifolds has been leaking for a bit now, and with a couple of days off work I thought I'd finally throw the headers that are in the shed on the 'Stang. Has anyone successfully changed out their manifolds with the motor in the car? Maybe this is a stupid question, but after fighting in the engine bay for the better part of this evening I can't see how, between the serious lack of handspace and the amount of rust keeping those bolts in place. I've already rounded one. So far I've utilized P.B. Blaster, my propane torch, hammer where I can and a breaker bar where I can.
If I do need to move the motor, how much of a project is this? I've got some other mods planned, and if its a serious PITA to pull the motor I'll do as much as is in the budget right now. This would be the first time I've pulled a motor. Blush
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#2
You can pull the bolt out of your motor mount and gain a few inches. Just have someone watch the firewall while you lift so as not to hit the hump with the engine. Unbolt the shroud at the top and slide it over the fan so you don't break it. Use a wide board on the oil pan so as not to dent it while lifing the engine.

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Just cruising along minding our own business when BAM!!! The LAWS show up.
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#3
Removing old exhaust manifolds can be done but, as you have found, it is a pain. Limited space and all.

When you do get one removed, clean it up a little and then put it back in and torque it down some. This will help relieve some of the forces on 'the last bolt' that you try to remove.

But at some point you just have to ask yourself if yanking the motor isn't easier.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#4
Thanks for the input guys. I might pull the mount bolt and see if that gets me enough room. If not ill overhaul.
One thing I overlooked in installing headers - is the heat going to be something I need to worry about in a daily driver? I can deal with the noise, but I don't want to damage anything. Do I need to wrap them?
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#5
I've broken all sorts of hardware trying to remove it, but honestly I've never broken exhaust manifold to head bolt (I've broken many of the manifold to exhaust bolts that I've even looked at funny, but not the ones holding it to the head). My suggestions to getting them out if you expect them to be a pain:
- a few days before (and every few hours after, or at least a couple of times a day) soak them down with a good penetrant- my current favorites are Kroil and WD40 has a specific "penetrant" formula out that works _really well_ (regular WD40 sucks), PB Blaster, liquid wrench, seafoam... can all be OK
- hit the head of the bolt with something metal (hammer... whatever you can get in there) just to shock them before you try turning them. If you really are worried about them you can do this when you spray them down with penetrant
- Make sure that you have a tight fitting socket or wrench on them and a good grip, so there is no tendency to slip.
- sometimes it's easier to turn them tighter to get them to start moving than to loosen, the trick is to get them all moving before you really loosen/remove any of them, loosening them can put more stress on the rest making them bind
- If all else fails get them nice and hot with a torch, and then hold some paraffin wax against them, it will smoke and wick its way into the threads and lubricate them. I've never had to do this with manifold bolts.

honestly, if at this point you don't have the bolts out I don't know that I believe that you did what I listed. If you don't and have managed to break one off, well my top contender of a solution is to hold a nut over what's left of it and fill the inside of the nut with a very, hot weld, welding it to the end of the bolt and then you can turn it out using a wrench/socket (and you put enough heat into it getting it welded that it will be loose)
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#6
Sometimes a metric socket that is close in size to the bolt head will fit really tight (with a couple taps) to prevent rounding...that's something from the early days here in the NE that worked with the rust buckets we worked on that sometimes helped. In my experience, exhaust manifold bolts can rust away pretty good as well as snap off. If you're lucky only the head will come off. That sometimes leaves a length of the bolt itself that can be worked out once the manifold itself it removed.

I don't miss these days one bit.
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#7
Bill73Ragtop;107124 Wrote:Sometimes a metric socket that is close in size to the bolt head will fit really tight (with a couple taps) to prevent rounding...that's something from the early days here in the NE that worked with the rust buckets we worked on that sometimes helped. In my experience, exhaust manifold bolts can rust away pretty good as well as snap off. If you're lucky only the head will come off. That sometimes leaves a length of the bolt itself that can be worked out once the manifold itself it removed.

I don't miss these days one bit.

Funny you say that. I just thought to use a 14mm this morning. It's been working like a charm. Unfortunately I didn't think about it before I'd already rounded 2. I'm going to try hammering a crummy old socket onto those.

Anybody have advice as for the heat? Is it something I need to worry about with headers? There's a place nearby that does ceramic coating. I'm not sure on cost though.
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#8
The only problem that I had was clearance with the starter. I put a set of Tri-Ys on a 302 in a 71 and the heat did impact the starter. An aluminum heat shield took care of the problem.

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#9
jb73Mach;107136 Wrote:The only problem that I had was clearance with the starter. I put a set of Tri-Ys on a 302 in a 71 and the heat did impact the starter. An aluminum heat shield took care of the problem.

Good to know. I'm thinking I might fab my own for costs sake. Part of the reason I am using headers is so that I don't have to pay to replace the cracked manifold. Tongue
I stuck my headers up into the motor to check fitment, and they're rubbing brake lines on the passenger side. I imagine this is something to worry about. I figure I'll just bend the brake lines around the headers and put another heat shield between the two - I might end up fabricating a heat shield to just envelop the headers all together.
After tearing into the exhaust, it looks like somebody has already been screwing around with things in there. Some of the bolts I pulled had washers and spacers, others didn't. There was no gasket between the manifold and the motor and there were studs on the passenger side, but not the drivers. I know everyone hears the previous owner excuse all the time, but man... It's frustrating. I still want to get rid of those rear air-shocks.
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#10
Argh... The PO... Angry


If only mine was as good as yours Wink
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