I recently purchased an 84 F 150 with a 300 6. iThe seller told me that the exhaust manifold was broken, but upon further inspection i noticed that someone broke the front bolt off in the head causing the gasket to blow. i dont want to remove the head, and there is plenty of working room because it's a straight 6. Any help would be greatly appreciated.

 

You can try drilling a hole in the top of the shank and using an "easy-out" to see if you can back the bolt out - my guess is you'll have to take off the manifold and put a vise-grip on what's left of the bolt to get it out.

 

Cant do that since it's broken off flush with the head. I guess i should have been more specific. I might be able to use a left-twist drill bit set. Have you or anyone tried this? if so, how well did it work?

 

There are two different scenarios with broken bolts. They either broke because they were loose and they fatigued, or they broke because someone tried to take it out, and they twisted it off.

With the first scenario, no problem, you can twist them out with your fingers, vise grips, left hand drill bit, easy out, they all work well.

With the 2nd scenario, there is nothing that is going to get them out, they are just too stuck, and have you ever tried drilling a broken easy out? In this case, what I do is very carefully center punch the bolt. Then take a small drill bit, and drill down the center as good as I can. Then I find the correct bit for the thread size, and drill the hole, and then run the proper tap through to remove the old threads.

 

Right on!

Remember that you will be seeing the tip of a thread on one side of the bolt and the heal of the thread on the other side of the bolt so finding center is an optical illusion, The more accuratly you are in the center of that bolt the better the end results will be.

If you get it accurate enough you can pick the bolt threads out and save the hole completly.

It's also a good idea to put a stud in that hole if possiable.

With scenario #2 I have been lucky a few times by welding a nut to the bolt, the trick is to shock the bolt real good first with a flat tipped punch, don't use a center punch.

Else take the head and have it EDM'd out.

-Enjoy
fh : )_~

 

I put a nut on them and weld the nut around the inside if its big enough and then turn them out.

Otherwise if they're small you can weld a roll pin to it on the inside and then turn it out.

I've had terrible luck with easy outs and left hand drill bits.

Here's what it looks like with a roll pin.

http://i102.photobucket.com/albums/m...6/IMG_0393.jpg

http://i102.photobucket.com/albums/m...6/IMG_0394.jpg

 

Franklin's got it right. And you're prolly looking a scenario #2... In the past I have drilled multiple small holes in a line and split the bolt. Never had any luck with welding washers and nuts on broken bolts. It takes a lot of heat to get a good weld and a stuck bolt in a cast iron head is a good heat sink. In any event, it's a major pain but dooable. Use lots of penitrating oil and there's always the helicoil if it doesn't go well... Good luck.

 

If you wind up having to heli-coil it, no big deal HCs are STRONG. Done properly, it will never give you a problem again.

 

Heli-coils are also Stainless Steel so less likely to seize the bolt into the head.

 

Hey thanks a lot guys. Everyone i talked to around here tells me to pull the head and take it to a machine shop, but i dont have that kind of money. I have been soaking it down daily with Sea Foam Deep Creep, and PB Blaster. I'll try and drill it out with left twist drill bits. I heard sometimes the bolt will come out while drilling with those, but i wont get my hopes up. Again, thanks for all your suggestions.