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Impact wrench technique when access is limited?

I was changing out the timing belt on my early 90’s Corolla a while back, and the biggest problem I had was a bolt (part of the front engine mount ass’y) that was on there so tight it was impossible for me to loosen. This bolt didn’t appear to be rusted. I tried some Liquid Wrench and heat, but it had no effect. This bolt was just put on really tight when the car was built. My thinking has always been that if a bolt won’t budge, just use a longer breaker bar. So I tried that, got out the big-beast breaker bar, all the effort I could muster … ummmphhh … and all it did was round over the corners of the bolt. And ruined the socket.

On this particular job, I was able to figure out a work-a-round; I discovered I could just remove a couple of different bolts and accomplish the same thing, which was to figure out a way to route the new timing belt through the engine mount ass’y and into the place where it goes. (Maybe one day the manufacturer’s will figure out a way to route the timing belt so it doesn’t require removing the engine mount??? I’m not holding my breath … lol … )

Anyway, I was wondering if I should have used an impact wrench? The reason I ask is because the access to this bolt was really tight. The only way to get to at it was using a ratchet and socket. The impact wrenches I’ve seen (like used for tires) wouldn’t have fit, because they look more like big drills. To use an impact wrench I’d have needed one that looked like a ratchet, not a drill. But I don’t think I’ve ever seen on like that.

So what’s the best way to loosen a stuck bolt when the impact wrench won’t fit in the space available? Are there ratchet shaped impact wrenches? Are there 90 degree adapters available for the normal drill-shaped impact wrenches? It seems like a 90 degree (or variable degree) adapter would have to use some kind of hardened gears or something, as the forces are too large for a normal 90 degree socket adapter.

Or maybe my problem was the socket. The ratchet held up fine, even with the big breaker bar. But the socket failed and rounded over the bolt in the process. I was using a twelve point regular-type (Craftsman) socket. Should I have been using a 6 point impact socket I wonder?

I was also thinking at the time if I had some kind of air-driven impact-hammer device, I could have held that up to the breaker bar to use it to hammer (vibrate) away on the breaker bar, hoping to vibrate the bolt loose without rounding over the bolt or ruining the socket.

Anyway, any ideas out there?

Anytime you run into a fastener that’s going to be a bugger to remove never use a 12 point anything. A 6 point tool is 1st.

As far as using an impact gun, it depends on the clearance and the angle to the fastener. Sometimes an impact U-joint along with an impact extenson will gain access to the fastener so an impact gun can be used. But the sharper the angle to the fastener thru the U-joint and the longer the extension reduces the output torque of the impact gun to the torque applied to the fastener.

So, sometimes it requires a cheater bar with a six point socket to break the fastener loose. Then you can buzz it out with the impact gun, U-joint, and extension.

As to your question to a 90 degree impact tool? They make air rachets But they’re not impact tools. So that wouldn’t help.


I’d have to see the bolt in question and where it is, and what’s around it to give a definitive answer, but it sounds like you’re saying the bolt faces some obstacle that’s very close to it which makes a straight shot at the bolt impossible, and there needs to be a 90 degree turn right near the bolt in order to access it, which would make using an extender on your impact wrench impossible. If that’s the case, make your own impact wrench:

Cover any sheet metal in the area with blankets, get a non-ratcheting breaker bar and drop a long piece of black pipe over the breaker bar (you get black pipe in the plumbing section of any hardware store). Then get a Thor hammer (a short-handled sledge hammer) with a metal handle and whack away at the black pipe. A good technique is to aim so that the end of the handle hits the pipe, with the head kind of wrapping around the pipe - this way you won’t end up with a glancing blow that diverts your hammer into something damageable. Obviously, use a 6 point impact socket to do this - a regular socket might shatter.

In situations like that, I’ve put a breaker bar on an impact socket and slip a cheater over the bar. I have an old five foot antenna post that is perfect for that purpose. I put some tension on it in the lefty-loosy direction and then bang on the end of the cheater with a dead-blow rubber mallet. The shock helps loosen things.

Edit: oops - just noticed @Shadowfax described a similar technique. Great minds think alike.

You’ve got some good advice above. In my opinion 12 pt sockets should only be used on 12 pt nuts and bolts. My input should not be taken as a commercial for any specific brand of tool, but early in my career I noticed that I had a lot of trouble similar to yours–rounded off nuts and bolts, stuck fasteners that wouldn’t come loose. And as I moved on up and was able to buy Snap-On and Matco tools to replace the amateur Craftsman stuff I had, I noticed that I had to spend less time (and therefore lost less money) fighting and repairing stripped fasteners. The Snap-on extensions don’t twist, the sockets grab the bolts and don’t strip them out, I’ve seen someone round off a brake line nut using a cheap flare nut wrench but a plain open-end Snap-On wrench loosened it.

Now of course the DIY’er isn’t going to spend $120 on a 3/8 ratchet or $450 on a set of 12 wrenches, but there is a difference in quality of tools and having high quality tools can make the work so much easier.

Fleamarkets can be a good source for the sockets and wrenches @asemaster describes. Over the summer I scored some nice Snapon sockets and wrenches for 2 bucks each.
Not that I’m big on fleamarkets but my wife is so, when she wants me to take her to one, might as well put my time to good use looking for good tools.

On some assemblies you need to move the engine to access the bolts. At least when they do not go with standard techniques. A six point hex really fits better, but some bolts are tough no matter what. You can get 6 point tools at a bunch of places. Do not worry about snapon prices because even sears craftsman has them. But you need to use them before the bolt looks like crap. Sorry.

For what it’s worth some companies, including Ingersoll-Rand, make an impact ratchet in 3/8" and 1/2" drive sizes. Yes, that’s impact not just a plain air ratchet. Whether it’s powerful enough for a given application or affordable price wise is another question.

Craigslist is also a good place to score tools. I see a lot of kids who went to trade school, bought a nice rolling tool box and filled it with brand new shiny tools, usually Snap-On or something similar, spent 3 months in school and decided being a mechanic wasn’t for them, so they’re looking to unload their tools. You’ll still spend a lot this way, but $5,000 for $30,000 worth of box and tools isn’t a bad deal at all. If I didn’t have my tool collection pretty full I’d jump on one of those.

A mechanic’s tool box is easily a $30,000+ investment. The collection of sockets in my 2 tool boxes likely weighs more than Lou Farigneau could lift. NEVER use a 12 point socket on a 6 point fastener. And there is a significant difference in the quality of Snap-On tools compared to others in my experience. For the DIYer it’s hard to beat Craftsman though.

6-point sockets should be a basic part of the toolkit of anyone who works on cars. As should be an impact wrench and impact sockets. The pulsating really does make a big difference.

A standard U-joint doesn’t usually work that well for tight spaces because its maximum effective angle of articulation is low. Bend a U-joint beyond about 20 degrees and it repidly loses function.

But there are 90 degree offset attachments made for impact wrenches. I’ve posted one in the following attachment.