Stubborn Bolts

[vettedog72]

I need advise on how to remove rusted steel bolts out of corroded aluminum. Liquid Wrench, kroil, or what is the preferred solvent? What is the best "easy-out"? What works best for you? Heat from a flame is out of the question for me, but I wonder if a heat gun works for any body?

 

[DrEntropy]

Kroil or PB Blaster. A real heat gun may get hot enough and repeated "cycles" of hot-cold-hot-cold over time while applying penetrant. Another thing to try will be physically shocking the thing. Whack it 'smartly' with a hammer a few taps. These bolts are snapped off? No easy-out I've ever used is 100% "best". The ones I've had the best luck with are Snap-On ones. They seem a bit less prone to break.


Is this aluminum thingie something you could lug to a machine shop? What're we playin' with here?

 

[TRDejaVu]

I've found that once it has soaked for a while it also helps to try to tighten it slightly before trying to back it off. I have had good success with that as it lets you set up a "rocking" action, although you need to develop a feel for it so you don't strip the thread.

Good luck.

 

[BritCarFan]

I've always used PB Blaster. And tighting the bolt/nut a little bit to break the rust helps a lot. Shocking with a hammer may also break the bond.

 

[racingenglishcars]

HEAT!!

There are other threads about this subject around here somewhere. (I think "other cars" about a 928 manifold)

 

[YankeeTR]

let it soak for several days...keep spraying it with PB or Kroil...the old tightening then loosening trick works great, too.

 

[AweMan]

Aluminum and steel are not a good mix. The electrolisis action between the dis simular metals creates a very rapid corrosive action which bonds the two metals together. Sometimes almost like they are welded to each other. Heat is your best bet. Realising you said heat is out of the question, the advice given above is about all you can do. Chances are, you will damage the threads in the aluminum {nature of the beast} especialy if this part hasn`t been dis assembled recently. IF by chance you do manage to get the bolt out, use copious amounts of antiseize on re assembly.

 

[DrEntropy]

...use copious amounts of antiseize on re assembly.

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif And stainless bolts in place of steel where a grade 5 is used can be of benefit, too.

 

[AweMan]

Arrrrrgh: I didnt mention using S.S. bolts in place of the steel ones, I must have a senior senile disibility. /bcforum/images/%%GRAEMLIN_URL%%/lol.gif
Good one DOC.

 

[Exotexs]

Aluminum and steel are not a good mix. The electrolisis action between the dissimular metals creates a very rapid corrosive action which bonds the two metals together.

I may have to disagree there, though I am not an expert in chemistry, but my 1965 S type has a Heater Valve that is half cast aluminum (the top half), and half stamped steel (the bottom half).

After 40 years it failed, so I sliced the "crimp" edge seal to find out what's inside. I found two rubber diaphragms and a spring, the main diaphragm ruptured, allowing coolant to jet through the weep hole, tipycal failure mode.

I found no electrolisis action or even corrosion inside, other than the wear and tear and metal staining of 4 decades of use. The two halves separated easily once the crimp seal was opened, they were not "welded" together as one would expect. So the Myth is Busted!

Ex

 

[DrEntropy]

See Bret's post(s) with regard to the bolts on the aluminum Porsche engine in the Other Cars forum. Photos included.

Electrolysis IS a big factor where dissimilar metals are involved. Galvanic reactions too. Have you had occasion to remove head studs from that Jag yet? If you're lucky it's always had proper anitfreeze mix. There have been Jag heads all-but welded in place by electrolytic reaction in my past. And one heater valve is no evidence of "myth".

 

[DrEntropy]

Arrrrrgh: I didnt mention using S.S. bolts in place of the steel ones, I must have a senior senile disibility. /bcforum/images/%%GRAEMLIN_URL%%/lol.gif
Good one DOC.

I only mention it 'cause most folks don't consider it. Stainless fasteners are cheap insurance in these applications.

Look what I'm used to dealin' with: Alfas are all alloy engines, wet liner'd. The Lotus T/C 1600's are cast iron blocks with alloy heads. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

Every Jag I ever laid hands on got stainless bolts in place of ferrous steel wherever practical. We had half a fortune in stainless fasteners at the shop. Last V-12 Jag engine we did was a work of art when finished. /bcforum/images/%%GRAEMLIN_URL%%/shocked.gif

 

[AweMan]

During my welding tenure I have dealt with more aluminum with steel bolts than I care to remember. And Corrosion, {wheather it is caused by electrolisis or not} IS a BIG factor as to IF they {the bolts} come out of the aluminum part or not. IF they {the bolts} don`t come out relativedly easily, its not going to be fun nor pretty removing them! The ammount of corossion these parts have depends on multiple factors. The main one bieng if proper assembly proceedures were taken IE antiseize. proper torque, ECT. Secondly exposure to the elements plays a great deal here. sometimes even using heat to heat the aluminum part and then attempting to remove the stuck steel bolt will result in ripping the threads right out of the aluminum because they are corroded so badly in place. With a part made out of two dis simular metals {In the case of the heater valve}, Beacuse of the difference in expansion rates in these metals {especialy in a hot/cold scenario}. Where the dis simular metals are adjoined there is more than likely a bonding agent in place to prevent leakage and/or seperation of the part, isolating these materials from one another. Although it is ture that complete isolation is not possible because of the conductivity of the coolant in this case. Having said that the coolant does one more thing, it prevents oxygen or atmosphere if you will from reaching the surface of either metal where the coolant is present therefore preventing corrosion on the inside of this part. Oxygen Or atmosphere, moisture {hot/cold scenario plays a role as well} on Aluminum it creates Aluminum oxide {A type of rust if you will} We all know what aluminum Oxide is used for {Mainly grinding/sanding abrasive products} a very hard durable substance {harder than even steel} So it stands to reason that once this Oxide {Corrosion} is present inbetween the base part {aluminum} and a steel bolt, the bolt is going to be very hard to remove and chances are the threads in the aluminum part will be destroyed in the process.
Ok Ok Ok I know! on and on and on!
Sorry

 

[DrEntropy]

DON'T BE!!! I agree TOTALLY! Wish I had stock in Heli-Coil!! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

 

[RonMacPherson]

When AHM(Acura) came out with the aluminum suspended NSX in what 94? There was a big blurb in school and in the service manuals about the electolytic action that occurred between the two different metals when they were in contact with each other and any movement was encountered.

All aluminum to steel retainer bolts came with a special plastic plug insert in them(fastener to be used one time only) to offset the galvanic corrosion. Since then MB and and BMW and Volvo, and Saab(just to name a few that I've encountered are supplying bolts with a plastic covering on them for the same purpose, to offset the corrosion.

Anybody got an NSX servce manual, They should be able to pull the name of the chemical out of the book, My grey cells, memory recall wise, are encountering a "greyed" out phase, just at present.