I'm going to be doing a lot of dissassembly over the winter. Many of the bolts I'm working with will not have moved since the day the car left the factory. So far I have been lucky. Only casualties have been bumper bolts and one rotor retainer screw. I've learned that a sharp rap with a hammer on the breaker bar is preferable to just torquing it. I've never worked with air tools but that is basicly what an impact wrench does. So my question is whether or not an impact wrench is the right tool for removing things like exhaust headers. Or is it just too powerful for risky bolts?

Prior to any disassembly I try and soak all bolts with a penetration oil. I use my impact wrenches all the time. Check to see what the torque of your impacts. I use my 450 to remove axle nuts and suspension parts. The engine parts only take a small amount torque so don't use any thing too large.

The impacts are good because they do the hammering for you prior to the bolt coming loose.

For risky bolts the best solution is to use lots of loose nut, daily, for several days. If at all possible, use heat on the nut or part. When you unscrew a bolt, unscrew a little, then screw it back in a little, obviously you need to unscrew more than you screw in, but going back and forh will help. You will develop a feel for how much torque you can apply and for how a bolt feels when it's about to break. When you get to that point, stop ! Squirt loose nut again, daily for a few days etc . . .
Giving the bolt itself a good rap with a hammer will also help sometimes.
The main things are loose nut and heat.
Michel Richard,
In wintry, salty, Montreal

If you use an impact or even a breaker bar MAKE SURE YOU USE 6 POINT GOOD impact sockets

Penatrating oil , and heat are good to help. if the bolts or nut is so rusted to the other piece that something will break, well, it will break with either a breaker bar or an impact wrench, although more force can generally be applied with an impact wrench (then again, a long enough breaker bar will match the impacts torque) Nice thing is an impact wrench is not likely to lknock a car of the jack stands like a long breaker bar could.

i have found sometimes heat from a little propane brazing tourch will work, but I found best results on large parts by using a real oxy / acetelyne tourch, the heat is much higher, and that means faster heat up of the part, which means more localized heating. The goal being to heat only the areas outside the bolt (ie the nut or the threaded hole) withjout heating upt he fasterner itself, you want the hole to heat and expand, and you want to keep the internal threaded part cooler (so it won't expand as much) High temp heat will better, cuase it will heat the external part so fast, heat will not have time to heat up the external threaded piece (the bolt) a small propane tourch on a big b=part my not get enough heat to expand a massive part enough before the bolt also heats and expands.

MAPP torch
penetrating oil
6 point sockets
variable impact

If the nut or bolt has a flange on it, the good old fashioned hammer powered impact drivers can do wonders. You hit it with a hammer, and an internal cam rotates the socket. It only works where you have alot of room, but it works so well because it applies an impact in rotation AND downward, which helps unload the threads. They come with screwdriver bits too, which are great for door striker plates and rotor retainer screws.

Thanks guys. I needed a little push to go out and invest in a compressor. This will do it.

In my browsing I have not seen a variable impact - sounds expensive. I'll keep my eyes open for one. Read about the MAPPS torch in a previous thread. Sounds like a good tool - convenience of propane but with a lot more heat. I only use 6 point so that's all good. Can't find PB Blaster up here but I've tried a variety of other penetrants - usually liquid wrench.

Should be fun. I'm really good at taking things apart. Putting them back together again - not so much

I had always wanted air tools. Once I got them I seem to only use them to remove wheel bolts and that is about it. If you have a high risk bolt and if you bust it is going to be a pain to ge the rest out - I'd do it by hand, you can feel when things want to go bad - can't do that with an impact.

True - no substitute for actually feeling the shear. But having said that I don't think I have ever recovered a bolt when I felt it going. You stop, say ah shit, worry about it, spray in some penetrant, heat it up and then it breaks anyway.

I do understand what you say about it being something that you expect to be the greatest thing since sliced bread then becoming a boat anchor. I'm going to start cheap and see how it goes. Kinda goes against my normal avoidance of cheap tools but until I see how I use it I don't want to buy decent stuff. Better to replace a cheap tool that I wear out quickly than to have a really expensive boat anchor.

I agree on that. Some cheap china speiail air tool sets have been seen at Kragen autoparts, like about $100 gets you a half dozen different air tools. Buddy bought one, and it is great, probably wouldn't last long with daily use like in a commercial shop, but for once and a while home use, its a great deal.

the air compressor on the other hand is always useful, blow out dirt, fill a tire, paint sprayer, etc... If you plan on using an spray painter, or an air tool like a sander (which you may run countinusly for many minutes verses an air wrench that is on for a few seconds at a time) you need to make sure the compressor has the right rating. You need enough pressure AND flow (cubic feet / minute (CFM) for the tool s you may buy later.

For a compressor you want to buy the best you can afford if you plan on it as a base for future air tools. Air impact wrenches require a very small CFM (but pressures in the range of 100-150 psi) (go for the higher pressures, the 100 psi i have found is marginal)
A paint sprayer or sander is going to require much more CFM on a countuinuos basis than say an impact wrench, so the air pump has to be larger. Tank size is also important, bigger is better, cause if you got a big tank, you can still run some large CFM air tools, even with a smaller rated pump, becuase you have the tank to use up, the air pump may not be able to keep up, but a large tank may allow you to run for say 5 minutes on the sander, then stop and wait a minute for the pump to catchup. re-pressureize the depleted air tank, and then you can run again. get a dinky tank with the same pump, and you'll find you;ll only be able to run the sander 30 seconds before having to have to stop and let the pump catch up again.

Important considerations

PS it is important to drain tanks periodically. at least once a year more if you run it a lot or if it is humid.

Spend your money on a compressor, do the pneumatic tools on the cheap - if you use it a bunch and it breaks - then upgrade. I had a 35 gallon unit from HomeDepot I think it was a 5HP unit - way too small for the blast cabinet, sanders etc.

wow! 35 Gallons was too small? I've been considering 25 gallons as a big unit. I'm kinda space challenged in the garage so I don't think I'd go much bigger than 25 Gallons. I also want something that I can lug downstairs in the winter. I'm mainly interested, for now, in an impact wrench, a mini grinder and perhaps an air hammer. The hammer is not important but seems to come with a lot of the el cheapo kits. If I have one I'd try it on the floor pan tar. Sanding and heavy grinding I'll do with electrical tools. Painting - not much chance I'm going to try that but if I do I can always rent. So the 5scfm@40psi (around 4-5hp) class of machine is probably going to have to be good enough for now. Watching e-bay and looking locally for a factory refurb or similar. Gotta be careful on shipping charges though.

Hmm, maybe it was a 30 gallon unit. At any rate you have to be patient and use a technique (with a blast cabinet), you can't just use a steady stream, that only works for about a minute or so before the compressor kicks back on and it is all downhill from there. If you do short blasts a second or two each seems to make the most of a compressor that is of smaller size.

hmm. I wonder if compressors in Canada are rated in imperial gallons. We could be talking about the same thing. 25imp gallons = about 30 US gallons. Have to look the next time I'm at Crappy Tire.

I use an ELECTRIC impact wrench (got it before my air compressor).

If you're looking for PB Blaster (which I like too) I've bought some in Ogdensburg NY, at the NAPA store out just off the highway.

A hammer-driven impact wrench is a good thought too, although most I've seen are 3/8" drive. plus there's often no room to swing the *!!@# hammer!

Don in Ottawa

for folks who can't find pbblaster or aerokriol locally, you can order directly from kanolabs. www.kanolabs.com. when i ordered from them they had a 2fer sale.

k