Partial Bolt Stuck in Head for Exhaust Manifold - Help!

[colnago]

After installing the heads on my rebuilt block, I found that the top bolt hole for Cylinder #6 has a partial bolt in the threaded hole for the exhaust manifold. The bolt is about 0.32" into the hole, so I can get a bolt partially into the hole before it bottoms out against the broken bolt. So, should I try to get the bolt out (and if so, how), or is 0.32" enough thread to use a short bolt for this one manifold bolt? The rest of the bolt holes seem to be fine.



Joseph

[eggman918]

If it's a top bolt and you have access to a cutting torch you can remove it by heating the bolt red hot first then hitting the O2 lever it will blow out the steel leaving only some slag in the hole that can be easily cleaned up with a tap

[Ranchero50]

You want at least 1.5 x the bolt diameter in threaded depth so no, .32" isn't deep enough. Depending on your skill set there are several different approaches to take.

If you are a competent mechanic, turn a 1/4" or 5/16" insert for the manifold hole and use it as a drill guide. I'd probably run an end mill of the drill diameter into it first to face the broken bolt off so the drill isn't as apt to walk across the broken face.

If you don't feel comfortable or have the ability, pull the head and let a competent machine shop remove the broken bolt. It's a 15-30 minute process on a mill.

As said above, you can use an O/A torch for the top hole but you need to know what you are doing.

One thing I highly recommend not doing is free hand drilling it. It's too easy to screw up and once it's screwed up, the next step is to screw it up even more. Then it becomes a machinists nightmare and you'll pay accordingly.

[sargentrs]

Just randomly thinking about your situation. How about something like a threaded drill guide bushing? http://www.profhdwr.com/66120.htm. Not sure what the thread is on the head but .32 might be enough to thread that in straight n start drilling with a 1/4" or smaller bit until you have enough of a straight hole in it. Maybe even use a left handed drill bit. Might be enough torque to back it out. If not tap it for a LH thread and try a LH bolt. By the time you've bought all of this and done all of this, hopefully without making it worse, you could have removed the head and taken it to a machine shop, faster and cheaper. Otherwise, drill it out larger and helicoil it.

[colnago]

Well, pooh! Not the answer I was looking for! I was really hoping that an army of Ford angels would ride rainbow unicorns to my front door, and say, "Don't worry, Joe. You can leave it. Everything will be fine." But they didn't, so I just ordered a set of bolt extractors. I can at least ignore this problem until next weekend. If all else fails, drill and helicoil. Ugh! I hope not.

By the way, the rest of the top holes for the exhaust manifold bolts were clean, but it got to be really difficult to thread in a bolt. Is this normal? Should I use a tap to clean the threads? Did I just get paint in the holes when I painted the block? The bottom holes were fine. Mostly, I'm worried about breaking another bolt when I put everything together.

Joseph

[Ranchero50]

Always chase the threads before putting them together.

Also, make a drill guide so you don't bore into the casting. Seem it done way too many times.

[pchelp101]

After installing the heads on my rebuilt block, I found that the top bolt hole for Cylinder #6 has a partial bolt in the threaded hole for the exhaust manifold. The bolt is about 0.32" into the hole, so I can get a bolt partially into the hole before it bottoms out against the broken bolt. So, should I try to get the bolt out (and if so, how), or is 0.32" enough thread to use a short bolt for this one manifold bolt? The rest of the bolt holes seem to be fine.



Joseph

Joseph I just spent the last two weeks removing two broken exhaust bolts, the first thing I can say is " don't rush" ! I was able to get the first bolt out using an easy out, the second I broke the easy out inside the bolt. It took some research but I found that a dremel and Diamond bit removed the easy out and the remainder of the bolt. I finished by re-tapping all 16 bolt holes and some grade 8 bolts and plenty of anti-seize.

[Manny]

Take your time get it out it will help you greatly it just stinks.