Seized bolt removal - shrouding at rear of engine

[Higsy]

I am currently stripping down 1985 Carrera 3.2 engine and have got some problems with seized bolts which held (very rusty) metal panel/ shroud at rear of engine. The panel has in large part rusted away so I have been able to detach it but still have 2 seized bolts to remove - see photo. I have applied copious releasing fluid but am concerned that I will shear them off when applying any serious pressure.

Any ideas on how to tackle it?

[quint22cp]

You can try heating up the aluminium but go easy on them as when I had exactly the same situation I ended applying a bit too much force and breaking the casing around that bottom bolt. Fortunately I was able to rebuild the case with Belzona and drilling and tapping a new hole.

[cgarr]

A few good hits with an air chisel on the side of the bolt head, work it side to side to break it free without shearing off the bolt, if no air chisel then a good punch will do, keep working it back and forth and it should come right out.

[OldTee]

This procedure may work better with the top bolt than the bottom but give it a try. Chances are the threads are not all that bad and not as rusted as the bolt head. Given that soak it in wd-40 over night. Then put a allen socket in with a long shank. Then 'tighten' the bolt just a little. Not much. Then try to back it out without striping the inside of the allen. If it doesn't break free, then add some heat from a propane torch. I would use some diamond paste on the tip of the allen to help purchase. Good luck.

[jhora]

If all of the above fail....then patiently drill them out....requires a very good drill bit...get a bit that is just under the size of the bolt....drill out...then you can use a bolt extractor...this taps into the drilled hole an turns left to remove.....looks like a regular tap.....then you can clean up the hole with a regualr tap......remember take it slow!
Good Luck!

[R390]

there is a liquid at Homedepo call "a must for rust" works good spay it clean off rust and then try the following.


Heating it up

reverse bolt extractor

some wd40

and just repeat the process.

[Dynamohum]

Just went through the same thing with sized bolts on my 3.2

This worked for me. 1st clean the area around the bolt free from grease and oil then wire brush the head of the bolt best you can. 2nd get a hammer and mild steel punch and give the bolt a good rap on the top of the head (not so hard that you mushroom it or break castings but hard enough that it will shock the threaded part) At this point you can gently try to turn it, if its not sized to bad it will start to move from this point and if there is any movement then soak it with WD40 or other good penetrating fluid. If it still shows no sign of movement, then you can hit it again then apply heat (Oxy acetylene torch is best with smaller tip) you need to heat the head cherry red, then shock it with water, do this 2 or 3 times, only heat the head and only till its nice cherry red not yellow hot, then cool it rapidly (this will shock the entire bolt that is in the casting) When it is cool to touch, try turning it gently if it moves at all soak it with penetrating oil and work back and forth ( go from trying to loosening to tightening gently) this will allow the penetrating fluid to work down the threads. Usually by this point it will turn, if not alternate hit it hard on the head, then heating, quenching. In my 30 years of experience if have found Most will come free with this method, but on occasion the odd one is so sized that it will not come and you will end up breaking it.
If it breaks, grind the top flush to the casting, carefully center punch it and drill out the broken bit and chase or re-tap threads.
Take your time, be patient, and not to much force.
Hope this helps.

[Higsy]

Thanks all for the suggestions. Will give it a go at the weekend
Cheers

[911pcars]

You can do better than WD-40, the all-purpose lube, preservative, penetrating oil and elixer that tries hard with a good marketing program. Try Kroil or a penetrating oil equivalent. They work better to help dissolve corrosion.

Sherwood

[911 tweaks]

Sherwood... I tried a can of Kroil and I can't tell if it works better than any of the other penetrtants I have i.e. wd40, gibbs, wurth I can't remember what its name is, pb blaster, liquid wrench and I am sure a few others.
*** SO, my question is: do you or any one else know what is the "KEY" active ingredient(s) a penetrant needs to contain to be a great product & perform ??

Thanks to whom ever can 'crack' the code with what the specific chemical(s) is that does the trick !!
Bob

[lucittm]

Bob,
In the penetrant world (I was involved in preventing corrosion rather than attacking it after it started to do damage), the key is low viscosity. The thinner the liquid, the better it is at penetrating. The problem is that many solvents penetrate well, but they don't lubricate. Some actually allow the metal surfaces to move closer together by removing films.
This is bad.
The goal would be to find a liquid with low viscosity (measured in centistokes, where distilled water is 1.00) like diethyl ether (.32), mercury (.118), methyl iodide (.213), or toluene (.68) and combine this with an extreme pressure lubricant such as dimethyl disulfide or lead naphthenate. Of course, all these componds can kill you. This is why cracking the code is so difficult.
I personally like to attack the offending metal with galvanic or chemical corrosion. In aluminum, the galvanic approach won't do because it is a low nobility metal and we want to preserve the structure and not the fastener. So, you could use a mild acid to attack the carbon steel fastener. Citric acid is good but it takes a long time. Vinegar is good if you can get the strong stuff. Nitric acid is the best if you can get a 50% solution. Don't use hydrochloric acid, it loves to eat aluminum.
The procedure is to work from the bottom of the threaded hole or drill a small hole and inject the acid into the blind hole where the bolt is. You have to rinse it out well when you are done.

For these two small 6mm bolts, I would use the heat, quench, tap method described above. If that fails, drilling them out is not that bad.

Mark

[911 tweaks]

thanks Mark. I will work on your ideas as I surf the internet for the best chemical.
Bobi

[304065]

Use the Blue Wrench. Works every time.

[911 tweaks]

can you be more specific John as to what the "Blue wrench" is... maybe a picture ??
Thanks, Bob

[TimT]

can you be more specific John as to what the "Blue wrench" is... maybe a picture ??

Now that's some funny schiess

Blue wrench= Hot wrench?

lol

[cgarr]

The Blue wrench is usually right next to the bfh!

[304065]

This is the blue wrench.

[equality72521]

Originally Posted by quint22cp

Belzona

That brings back memories from my motor winding days. Good stuff, will outlast steel and nearly as strong.

[Dynamohum]

Originally Posted by john_cramer

This is the blue wrench.

I got me one of those Blue Flame Reamers also, there Great!