snapped exhaust stud

[bikerzx7r1981]

Hi All

Was on her a couple of weeks back, about a snapped exhaust stud - dash after much penetrative fluid, mould grip time and finally bought a welder and welder nuts on it just aint coming out.....

There's approx 10mm left of the thread sticking out but can't thread damaged so can't put bolts on.

Just after advice on what to try next. Does anyone think these might work (it's difficult to get the sockets on due to the gaps with the engine fins.

http://www.machinemart.co.uk/shop/product/details/pro57-4-pce-stud-extractor-set

Getting desperate now, so any help appreciated.

Cheers

[GateKeeper]

I wish I could help you out, but I had the same issue, and I had to drill out what was left, now I have a larger hole, need to have it welded up and then drill and tap a new one...

Best of luck

maybe the sockets you mention and some heat at the same time, might loosen things up enough to get it out

Cheers

[bccap]

I don't know what you've tried. But here goes. Run the engine until it is hot, spray pb blaster or some other kind of penetrating oil on the stud, then whack it good and hard with a hammer. I'd do this for a few days. Then weld your nut on, or use vise grips. Heat the engine up, more fluid, a good whack. Then make your first motion to tighten the stud to break the bond and then hopefully it will loosen on your next motion to loosen it. Make sure the engine is hot. I'm sure you already know this, but WD 40 is NOT penetrating fluid. Good luck.

[sedelen]

I had an outboard motor that I used in salt water, I burned up the impeller in the lower unit and decided to replace it. The lower unit was aluminum and held on with stainless steel bolts. There was alot of electolysis and corrosion from it, especially when theres two different metals in salt water. There were about 10 stainless steel bolts holding it on.
I couldn't break free any of the heavy stainless steel bolts, so I decided I would use a long piece of pipe over the wrench to gain the leverage, I managed to get three loose and the others I snapped the heads off of.
What was I gonna do? I had a mechanic friend and called him. He said just take a torch and heat up the aluminum around the bolts, not the bolts. I did that and they all came out as easy as pie.
Your situation reminds me of that. Might work for you.

[Nessism]

Make sure the nub is well coated with PB Blaster then get a propane torch and heat it up red hot. Let cool. Try to turn the nub both out and in, but don't force anything. If it won't budge, try heat again. Repeat a few times until it starts to move. Once you can break the piece loose, you still need to go easy. Work it back and forth and keep it wet with the spray oil. This typically works as long as you don't force anything.

[snyderman]

I agree with Ed. The way the heating up works is expansion from the heating and contraction from the cooling loosens the bond. I had a stuck cylinder stud that I worked on for a good couple of weeks. the first day I heated it up let it cool a little and sprayed PB Blaster. The next day I tried it when it was fully cool. Then I heated it up and sprayed, trying it the next day. Finally I welded a nut to it (the heat from that sometimes helps a lot), let it totally cool, then did the back and forth with a wrench. It finally broke loose.

Hope that helps,

[spyug]

As the others say, heat is the key. If you don't have access to oxy/acet then use a mapp gas rig (yellow cylinder) available from the hardware store. It burns hotter than the standard propane (blue cylinders).

Heat the head around the bolt rather than the bolt itself spray liberally with PB Blaster or the like, try and or repeat as necessary. It might take a few tries to get it.

Let us know when you get it out.

Good luck,
Spyug

[Normk]

It is best to heat the broken fastener rather than the area around it, especially when dealing with steel into aluminum. Heating the aluminum will not result in much general expansion because it would be necessary to heat the entire structure in order to achieve this. In addition, heating of the aluminum structure such as the cylinder head to a significantly high temperature, such as 400+ F, risks warping of the material or creating stress fractures.

The heating of the area will typically result in also heating of the steel fastener, and unless the heating rises above that of normal operation which is unlikely, no benefit will be likely to occur.

Heating of the fastener, especially rapidly which is the trick, results in the fastener's expanding at a greater rate than does the surrounding aluminum. This expansion of the steel fastener has one or more of the following effects:

1) Stretching of the aluminum around the hole such that the size of the threaded hole becomes slightly larger resulting in less friction when turning the fastener.

2) Crushing/deforming/destroying the corrosion materials between the parent metals of the fastener and aluminum, again, resulting in a release of the fastener.

3) Rapid heating of the steel to bright red will cause the steel fastener to attempt to expand to a larger diameter than can ba accomodated by the hole as in #'s 1 & 2, but the resistance of the cooler aluminum around the hole will resist the expansion. The radial expansion force will be channelled from a radial vector into an axial one, resulting in length-wise stretching of the fastener. In order for this to occur some of the steel from the fastener will be forced to flow causing the growth on length but resulting in less material within the original cross-section. When the fastener cools it will become smaller in diameter than originally because of the material which has flowed to increase the length.

This effect results also in releasing the fastener's seized threads.

Welding a nut to the stud accomplishes all of the above as well as to provide a more effective means of driving (turning) the broken section.

Rather than canned spray bombs of penetrants, try a wax candle. It is amazing how effective is the wax when it has wicked up the threads.

Luck is also not a bad thing when doing this.

[1_v8_merc]

This might be the perfect time for you to learn how to use a Tap/Dye set.(re-threading)

Aluminum is very soft and easy to work with...

But first, you must buy some Metal drill Bits, and drill that bolt out.
(exhaust your other options First.)
-----
But then again...I really don't have much patience with stubborn bolts, if they don't come loose with a torch or welder, I drill the bitch and re-thread it for a Bolt that I have in stock....no questions asked. hehe.

[tkent02]

Rather than canned spray bombs of penetrants, try a wax candle. It is amazing how effective is the wax when it has wicked up the threads.

Never heard of this, I'm going to try it today.

[Suzuki mad]

Interesting way of going at the problem. Let me know if you have any success.

[chuck hahn]

I have a set of Craftsman stud extractors which I have used sucessfully. You say you welded a nut to the stud sticking out. You gotta really get a good penetrating weld on them. What i do is try to get the nut as far onto the stud as possible and you start the bead on the stud inside the nut and puddle it outward till the nut is welded very good to the stud. while it good and hot hit it with the oil..it will smoke like crazy so do it outdoors or have a fan sucking the smoke outside the garage door.

[Normk]

One aspect of this kind of thread is context and this needs be appreciated by those, especially inexperienced, reading the thread.

When I read Chuck's post, for example, it is immediately obvious to me that the information he posts is incomplete which it must be because it would require volumes for him to post his complete appraisal of the subject. I use his post as an example because it must be obvious to anyone that he knows this subject in great depth.

In addition, 1_v8_merc, Chuck, & I might (likely will) advance differing recommendations for dealing with the problem. There is no question in my mind that each of us would very successfully deal with the problem at hand despite that we may apply differing solutions. Part of this is because we have differing mental pictures of the presented conditions. We might, would quite likely, use the same strategy if we each had the problem at hand.

I wonder if, for example, most readers understand what is meant by
"puddle it outward" or recognize "metal drill bits"?

I urge anyone who lacks years of successfully dealing with issues of this kind to read between the lines carefully because it is human nature to jump to conclusions based on the first cursory impression and then to seek only "evidence" which supports this appraisal.

Training, years of experience and many horror shows resulting from application of imperfect appraisals of the situation have punished those of us who are experienced, to discard approaches which may have seemed to be appealing. I hope that no one is forced to experience these failures in order to successfully approach these problems.

While having extensive experience in removing broken fasteners or () a broken tap is valuable when presented with another instance, it is less enjoyable than a ride on a nice sunny day.

One should never hear differing recommendations from competent posters as differing regarding solutions but rather as differing appraisals of the information presented. Like most of the experienced members posting, I feel conflict between the effort in attempting to present a useful solution and the wish to help.

[silverhorse47]

On the other hand, when fools rush in, more experienced mechanics are developed.

S.

[Normk]