Fortunately, I've worked through my list of "big" issues to fix and have a mostly reliable weekend driver. Now, I have an annoying exhaust manifold leak that I would like to take care of. Assuming the manifolds have never been removed, what's the likelihood of removing them without wringing off a stud? I'm concerned that I create a bigger issue trying to fix a smaller issue...

'86, 302, factory exhaust

 

Penetrating Oil. Soak, Soak, then Soak again. When you think it's enough, Soak some more. Depending on the environment and if they have ever been removed, soak some more. If mine, after waterboarding the crap out of the studs with oil, I would apply heat if possible prior to attempting to break them loose. Then again, they may just break loose with no problems. I wouldn't rely on the later scenario.

 

Do you have the tools in case one of them does break off? One or two usually do.

 

Do what was said and use 6 point sockets or wrenches, 12 points can round off the heads.


Also if the SAE don't fit tight try metric 6 points.
Dave ----

 

Thanks guys! I may give it a shot and see how it goes. It's definitely not a daily driver so if one or two break it won't be catastrophic and would be on par with every other repair I've made thus far .

 

Tools, meaning drill,easy outs, torch? I've kinda also assumed it may be necessary to pull the head to gain good access to the studs as well...?

 

Please forget the easy outs.

A stud puller or a *Brand New* pair of Genuine Vice-Grip pliers are good for when only the head has come off.

A MIG welder and some nuts from the junk drawer are best when broken off flush.

Access is much better if you remove the plastic inner fender.

Use stainless steel bolts with nickel antisieze going back in.
I have a post in the wdydtytt thread on 12/11/16 showing what 20 year old stainless exhaust bolts look like.
I only had a problem getting out the (not stainless) stud that mounts my dipstick.

No loss of head with stainless bolt, and the threads are still 100% as well.
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You may need a right angle drill if yours won't fit in there. I see harbor freight has one for $30-$40.

As was mentioned, forget the easy-outs. They only work when a bolt breaks off for other reasons, and is not really stuck in the hole. These are really rusted and stuck in the hole, if the bolt itself could not get them out, a easy-out is certainly not going to remove it.

The trick is to drill it out. The hard part is getting a hole started in the middle. Take a center punch and as carefully as you can, punch a mark in the middle of the broke off bolt. Eyeball it afterward, if it doesn't look right, try again and keep trying till you get it in middle. You can lean the punch over if you need to get halfway onto a old punch mark.

Then get a very small sharp drill bit. Drill a very small hole, trying to keep it in the middle and the correct angle so it goes into the hole straight. If you need to lean the bit one way or the other in the beginning to get it more in the center, do so, and then once it drills in a little bit you can straighten it up and keep drilling. Don't try to straighten up too late or you will break the bit off.

Once you get this small hole looking good and centered, the hard part is over. You now need to open the hole up to the proper size bit for the threads. You can do this in a couple of steps using different sized bits. The final size is in the chart below. If you do not have letter or number drills, you can get close with fractional bits. You can then run a tap in the hole, and all the little leftover bits of the bolt will come out. If you are just a little bit off on your work in relation to the old hole, don't worry it will still work ok.

 

If you need help with the chart, a 3/8-16 bolt takes a 5/16 drill bit. I want to say that is what the bolts are on that engine's exhaust manifold. If they happen to be 5/16-18, those need a "F" drill bit. The closest thing to a F is a 15/64 bit. If you use that, you may need to waller it out a little bit if the tap is too tight in the hole.

Another common size on the engine is a 1/4-20. That takes a #7 bit. 7/32 is the closest, if the tap is too tight don't break it off, wiggle the 7/32 bit around to open it up a little bit.

 

I feel I need to add be VERY careful you don't drill too deep

There have been a few threads on this forum about having to deal with coolant coming out the exhaust bolts.

​​​​​​​It's a real mess that could have been avoided by paying attention or using a stop collar on the drill bit.

 

3/8-16 for exhaust bolts..

A cheap set of bent/angled picks can help a lot in getting the remnants of the bolt out of the threads before cleaning up with a tap.

 

Left handed drill bits when drilling out the broken stud.
Dave ----

 

I went through something like this a year or two ago but with intake manifold bolts. Even though I had direct access from above, it still sucked really, really badly and isn't as easy as it may sound... getting the hole centered and not damaging the threads is paramount.

And you're back to Square One when a drill bit breaks off in the hole.

In the end, taking the heads to a machine shop is BY FAR the easiest, fastest & most reliable method, they have the knowledge, tools & equipment to deal with this kind of thing.

BTW I agree with soaking in penetrating fluid ahead of time; using vibration & shock can help, too.

 

Drilling into the coolant passage isn't the end of the world. After all, many MOPARs come from the factory that way. And Rusty's passenger-side head is that way. I don't recommend doing it, but if you have to in order to get enough threads then run PTFE on the threads when you go back.

 

I've had tons of experience with removing exhaust manifolds and drilling out broken bolts. I don't even attempt to remove the nuts holding the pipe to the manifold without heating them first. If the bolts holding the manifold to the head are stuck tight and feel like they are going to twist off, I cut the head off with the torch; then slide the manifold off over the remaining bolt. Then you can heat around the bottom of the bolt and turn it with either a vise grips or a stud remover. Worst case scenario it breaks off and you'll have to drill it out, but you'd have to drill it out anyway if it broke off trying to remove it with the head of the bolt.

Trying to drill bolts out with the heads on the engine and still in the vehicle is difficult. I usually use a 3/8 angle drill. If I get the hole slightly off center I'll drill it large enough to get a 1/4" carbide burr to fit and use an angle die grinder to straighten the hole out. I've done it enough times I can usually grind right down to the threads without damaging the original hole.