I snapped a few bolts..

[JohnnyP]

Gary, thanks for the help. I was pretty sure about the propane torch, just figures I'd double check. I'll have to call my local shop and talk to them.

Thanks for all the advice guys/gals!

-Johnny

[Kellhammer]

I've broken the manifold bolts and it is no easy task drilling them out. If there is enough stud left you still have a chance to apply heat hit with penetrating oil such as PB blaster.

If it is broken off flush then drilling out will work, but your best to have some one with experience perform this task. Also, easy-out's rarely work and if you break them off in the bolt, your really in trouble.

Coincidentally, I was removing parts the other day from my 240 and did a web search about rusted bolt removal. Other than soaking the part with PB blaster for days , some people suggested heating and melting a candle onto the part. I gave it a try and it worked! It supposedly the heat draws the wax deeper into the joint and breaks thru the rust. This might work in some cases, but not all

[e-tek]

Other than soaking the part with PB blaster for days , some people suggested heating and melting a candle onto the part. I gave it a try and it worked! It supposedly the heat draws the wax deeper into the joint and breaks thru the rust. This might work in some cases, but not all

Ahhh the wax candle trick....I've tried it several times and it just has NEVER worked for me. I think it's just the heat anyways. Works every time - by itself!! Make sure you get it red hot!

[Langford Chuck]

All right then, in summary, for those new to the joys of working on rusty old cars.

I. Bolts (and to a lesser extent, studs) break because they are frozen into their holes, or to the nut, and the breaking point is lower than the torque required to free them from the fastener. Alternatively, they break because the torque applied to them is applied at an angle, and the mis-aligned force (often combined with rust) breaks them via this shear force. We will set this type of break apart for now, except to note that careful extraction with the right tools will reduce the chances of this.

2. This 'freezing' is either rust, or galling. Rust requires ferrous metals, which is the material for most of our fasteners, and is a chemical response to oxygen, water, and ferrous metals. Galling is an electro-chemical response, and applies to non-ferrous metals, like aluminum, or stainless fasteners in non-stainless nuts or holes. in either case the issue is twofold: the friction created by the deposition of new material (rust) or the chemical bonding of dissimilar materials.

3. There are multiple ways to respond to this problem. I focus here on rust, because, hey, we own zed cars, right, and so rust is our official mascot, and there are not many (stock) aluminum or stainles fasteners on a Z car. So, rusted fasteners.

There are five main effective responses:

* lubricant

* heat

* cooling

* shock

* extend the fastener

* cut your losses and drill it out.

It goes without saying that all of this is easier if you can clean up the head or nut area: i often just hit with a small wire wheel, or a small wire brush. Everything goes easier: you can see better, the nut/bolt head is cleaner and takes the socket better, lubricating fluid flows better, lesss friction once you loosen it, etc. I also assume the use of 6 point sockets. Finally, I assume the use of Never seeze when you finally replace the fastener it took hours to get out, so it will come out the next time with no fuss.

Lubricant:

First, we can apply a lubricant that will ease the friction between the two parts. Now, opinions differ widely on this one, but the following is a short list:

a) WD 40. Not real effective, but better than nothing, relatively cheap, and usually at hand. But if it was designed to displace rust, it would be called RD 40....

PB Blaster: many have rated this material quite highly (discussed at Hybrid z, and perhaps some threads here).

c) Kerosene. Even cheaper than WD 40a

d) Candle. i have never used this method, which involves heating the fastener and drawing melted wax into the threads. Perhaps I will try it out an see how i works. Seems cheap enough.

e) Kroil. number of good reviews. not so easy to locate.

e) many other commercial products (a good list can be found here:

http://www.crankshaftcoalition.com/wiki/Removing_rusted_and_broken_fasteners). Look for phosphoric acid content. Silicon is good, but not on its own.

f) amateur products: 1 part methyl hydrate (gas line antifreeze) and 3 parts ATF. Coca Cola does NOT work. it just makes a mess. Same with pepto bismol.

For the keeners out there, grab a bit of modelling clay from your kid's toy basket, and use to build a small 'dam' around the head, then leave the stuff to soak in its own little bath.

The other option is to change the situation, not by lubricating the material, but by heating or cooling to release the 'bond'.

Heating is the old familiar technique: use propane, or if it is a large stubborn bolt, MAP gas which gets hotter than propane. I have been using a propane torch with a swivel head and a self-ignitor and it is WAY easier than the standard fixed head. Well worth the extra cost. I have a small refillable tank from a barbeque with a a specific hose for the fitting on a propane torch. More economical, but it seems to be lower pressure and so less gas flow, meaning less heat. But I can use the hose to get the torch head in places the canister won't fit.

Now, there are two supposed effects here: one, in expanding different parts (the bolt or nut ) at different rates you create a 'break'. Tjhis means that the tecnique is to heat ONE part, as much as you and direct the flame, NO both the bolt and fastener. But also, note that if done properly you are annealing the fastener: that is, 'work hardening' it by the application of heat so it can withstand higher twisting forces. If possible, heat the nut, as it will expand away from the bolt. If you heat the bolt, DO NOT try to twist when the it is red hot: this is when it is weakest and will surely fail. Wait the ten seconds for the red to dissipate, then try.

Cooling on the other hand works on the principle of different rates of contraction. CO2 or liquid nitrogen are used here (ie, CRC Freeze Off). the nice thing about cooling is that is is safer in areas near rubber, or other flammable things, or paint.

Shock:

Usually, this entails giving the fastener devil a whack on the head, typically in line of the fastener (i.e., straight down). A sharp few raps is the key. Some suggest a series of small taps, to simulate the effect of an impact wrench. This works well with dissimilar metals. I usually do this with a socket on the fastener, but whatever works....

Extend the fastener:

This works for those times when you break of the head of the fastener, but does presume a welder and the space to work it. If there is some room left on it you can thread a new nut on the end, and weld it on. Alternatively, lay a washer down to prevent welding the nut to the part the fastener is on. Place a nut at least one size bigger than the shank of the bolt. Weld it inside the nut until it is close to full. The heat will help, and gives you another chance to work it out.

Cut your losses:

Lets face it, sometimes it is just as easy to crank it out, break it if you must, then drill it out. Obviously, this is best for sheet metal screws (like the ones that go into captive nuts and hold the turn signal sheet metal piece to the front end), or smaller bolts where they are accessible.

[JohnnyP]

A very extensive list, and VERY helpful! I tried heat, lubricant, shock to no avail. I decided to cut my losses on this one. I picked up a tap and die kit this morning. I'll just drill out the old stuff and re-tap the holes. Thanks a lot everyone for your help on this one. I will be coming back here for more help with my Z!

Thanks again gentlemen

-John

[doradox]

But also, note that if done properly you are annealing the fastener: that is, 'work hardening' it by the application of heat so it can withstand higher twisting forces.

[

Lots of good advice but annealing and work hardening are pretty much the opposite of each other. Annealing softens, work hardening, well, hardens. And you don't work harden by heating then cooling. That would be heat treating. You work harden by exceeding the yield strength of the material.

Steve

[Langford Chuck]

Sorry, I haven't checked this site for a bit.

Doradox is correct in pointing out my incorrect use of the terms. My bad, but it did encourage me to further research, above and beyond the by now substantial body of painful experience in dealing with rusty fasteners. Let me try again, and I welcome comments or corrections.

Heat has two potential effects on mild steel, especially mild steel with a decent carbon content, ie, better grade fasteners.

First, if it is allowed to be heat 'soaked' for a period of time, and then slowly cooled, it can effect the grain structure of the steel, making it more 'ductile', which means more flexible but less strong, which in the case of stuck fasteners means more prone to breakage. We thus don't want to anneal our fasteners, although I have in the past annealed sheet metal I was panel beating into a particular shape, when my hammering work-hardened it and it started becoming brittle. The strategy for fasteners thus seems to be to avoid prolonged heat soak, and avoid slower cooling off periods.

But heat can also produce hardness in steel. Heating and rapid quenching are in fact key processes in creating the hardness of the tools we use to break off fasteners. As steve points out, this is heat treating. While tool steel involves a carbon and alloy mix not found in fasteners, this none the less may explain why sometimes heating and then rapidly cooling (ie, with a spray application of lubricant) sometimes seems to work. I would welcome any input from engineers on this point...

"You work harden by exceeding the yield strength of the material".

As noted, we can harden by 'stretching' the material. While this gives some theoretical hope to working with mild steel fasteners, it seems to me in practice to be of no use, as if we could 'work' the material we would just take the darn fastener out and be done with it.

now, off to tackle some more rusty fasteners......

[Zedfoot]

Having stripped my "72, which I bought new and drove through 12 Ontario (salt) winters, then stored poorly, I have a lot of experience here. A propane torch doesn't concentrate the heat enough. Invest in a small, portable oxy-acetylene set with a very small welding tip for heating and a cutting torch. You have to have the female part hotter than the male, ie: heat the nut, cool the stud, or heat the aluminum block, cool the stud. The welding tip concentrates the heat so you can heat just what you want. For a stud in aluminum, heat it to just red and keep it there for awhile to let the heat transfer to the aluminum, then hit just the stud with Liquid Wrench. The LW will suck right into the joint, cool the stud quickly so it shrinks away from the aluminum and to some extent re-harden the bolt. Get on it with the wrench right away before the aluminum cools off. If it doesn't come easily, repeat the whole process. If it still doesn't come, soak it with LW every day for a week and try again. Do not try to turn a red hot bolt. IT will be soft and expanded tight into the hole. Red hot nuts are fine, but they are pretty well useless afterwards unless you re heat and slowly cool them. I was able to get every bolt and nut off my car without anything breaking by using this method.