as many people experience, I'v snapped 4 of the exhaust manifold bolts, 1 was 1 of the bolts that are on the end and come out the other side, the others are in the block, what do I do with them. I tried heat and chilling them but that didn't work, then SNAP. do I drill and tap 1 size up, or drill and helicoil?
exhaust manifold bolts are snapping
- Thread starter matt1967
- Start date
64.5 TX Stang
Well-known member
I believe that is where the almost comes into play.
Drilling and tapping the next size up is essentially the same as Helicoiling anyways.
Stepping up to 7/16 on the exhaust would certainly be cheaper than putting in Helicoils - but Im not sure the maifold will clear a 7/16" bolt in all places.
Another option - I have many times been successful at drilling out stepwise a snapped bolt and then just re-tapping it the same size.
Start with a small bit to get a hole started in the center, and step up to the tap drill size for that hole. I belive for a 3/8" it is 5/16. Once you get it drilled ot to that, chasing a tap up the threads will clear them out and you should be in good shape.
Stepping up to 7/16 on the exhaust would certainly be cheaper than putting in Helicoils - but Im not sure the maifold will clear a 7/16" bolt in all places.
Another option - I have many times been successful at drilling out stepwise a snapped bolt and then just re-tapping it the same size.
Start with a small bit to get a hole started in the center, and step up to the tap drill size for that hole. I belive for a 3/8" it is 5/16. Once you get it drilled ot to that, chasing a tap up the threads will clear them out and you should be in good shape.
What were you using for heating/ cooling?
What kind of wrench were you using?
Any idea how long it had been together?
What kind of wrench were you using?
Any idea how long it had been together?
It works great, but you have to be careful to make sure you get the hole started in the center. If you get off too bad, it won't work very well.
Use a punch to knock a good divit in the middle of the bolt stub. I usually start with that, and then move to a center drill - then go up from there.
Just take your time. I have done a ton of bolts this way. It even works to drill a Steel bolt out of aluminum.
Usually when you get close to the tap size for the hole, the remains of the bolt will catch on the drill bit and start to spin. Sometimes at that point you can reverse the drill and thread it out.
Good Luck.
Use a punch to knock a good divit in the middle of the bolt stub. I usually start with that, and then move to a center drill - then go up from there.
Just take your time. I have done a ton of bolts this way. It even works to drill a Steel bolt out of aluminum.
Usually when you get close to the tap size for the hole, the remains of the bolt will catch on the drill bit and start to spin. Sometimes at that point you can reverse the drill and thread it out.
Good Luck.
If you are heating the bolt up and then quenching with water you will harden the bolt making it nearly impossible to drill. You should heat the bolt and then let it cool back to room temp without quenching. This will release the rust holding the bolt and allow you to drill.
Just makin sure you were using real heat and not a 4 foot bar on a 1/2 wrench. Only other thing I have heard but not tried is to use wax after you heat it. I guess the wax gets sucked into the threads and cools at the same time so it works like a quencher and penatrant at the same time.
Hope you get those out and get back on the road soon.
A
Anonymous
Guest
As a veteran of many snapped bolts (I'm a lousy mechanic), I go with the progressive drill, then tap scenario. The only way I've found to free 'em up in the first place is lube it well, let it set, lube it some more. Then, very slowly, carefully, and methodically....Turn it right, turn it left, turn it right, turn it left, in progressive increments. Patience and persistence and easy on the torque. You won't think you're getting anywhere to start with but I'm surprised at what I can get loose. Also, in general, an air impact works better than a ratchet and a grunt. A friend and I twisted off his shock bolts this weekend on the first twist.
If you can find a set,get the LEFT hand bits for your drill.Of course you will need a reversible drill to use them.Working with older vehicles it would pay to have a set of those bits on hand at all times.Most of the time when you use these bits,the heat of drilling will losten the broken bolt and it will come out of its own accord with the left hand turning of the bit.Leo
pedal2themetal45
Famous Member
Maybe when drilling it out use a reverse bit so You are drilling it counter clock wise so if it catches or the bolt brakes loose it well back it out. Saving some time maybe..
Just my .o2
tim
Just my .o2
tim
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
won't need to do any drilling. the heat& chill worked, I sprayed PB blaster on them hot ( chilled, only until they were not glowing ), the snapped 1's, I heat and chilled after I got the manifold off, so tomorrow I can just put a stud remover on them and they should come right out, whail they were still hot ( but chilled a bit ) I sprayed PB blaster on them and it sucked up into the threads, they should come out with no problem.
I'm just glad I didn't have to drill anything. once I get the last 1 out, I'm going to start tearing the motor apart, gotta order the Ross Racing Forged pistions, have to get custom sized pistions anyway, to get the comp where I want it ( 8.3:1 ) and I can budget them. just gotta get the old 1's out to find out if any thing else needs done, such as being bored, dosn't appear to need bored as there is very little ridge and the bores and pistions look good from what I can see.addo":362enfyk said:
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