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How can I get the crankshaft bolt undone so I can change my timing belt?
you came from: Master List > Engines

This question shows up in the newsgroup quite regularly. The bolt holding the pulley to the crankshaft is on there TIGHT. Some folks have had so much trouble getting it started they've posted plaintive enquiries wondering if it's a left-hand threaded bolt! No, it unscrews the regular way, but don't kid yourself that you're going to undo it with a short-handled wrench. Having the car up on jackstands probably won't give enough room to swing the handle of the wrench you're going to need.

Why is it so darn tight? It's a well-known phenomenon called "embedment", where the surface textures of a bolt's threads and those of its receiving hole mesh ("stick") together. Honda warned its dealership technicians about it years ago, in this PDF document.

Also, older 4-cylinder Honda engines have a special quirk that very few other makers' engines do: They turn counter-clockwise, backwards from the industry norm (Honda's V6 engines turn clockwise). With clockwise engines, you can place a wrench on the bolt, position the handle against the frame just so, then blip the starter. This will break the bolt loose. You CANNOT do this with Honda's older counter-clockwise 4-cylinder engines.
Before shutting the engine down for the last time, check to see which way it turns. If the timing belt end is towards the American-style driver's side (left side of the car as viewed from the driver's seat), then the engine turns counter-clockwise in the traditional Honda manner. If the timing belt is on the American-style passenger side, then the engine turns clockwise.

A warning: You MUST torque the crank bolt back down correctly after you put it back. Failure to reinstall it correctly (including putting oil in the correct locations on the bolt) will result in the pulley eventually falling off while driving. Consult your shop manual for correct torque figure and procedure. This is true whether your engine turns clockwise or counter-clockwise. Loose bolts fall off, period. Don't let anybody tell you they somehow "tighten" if the crankshaft turns clockwise.

Now, here's a list of different methods of bolt removal: How to get it tightened back up again

The physically easiest way to get the bolt loose
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An impact wrench. The best method by far.

DeWalt 325lb electric impact wrenches are available from any industrial rental place for less than $20 per day. You might have to buzz back-and-forth (tighten for a bit, loosen for a bit, etc.) for a minute or so, but it will probably eventually come free. Mine did, and I live in the Rust Belt. These are very handy as they require no $1,000 compressor.

If the bolt does not let go no matter how long you buzz with the DeWalt, you'll need some heavier artillery: An air impact wrench backed up by a big compressor. If a regular 1/2" drive air wrench won't work, try the Big Bertha of impact wrenches: A 3/4" drive 600 ft-lb job.  If even Big Bertha fails, or you can't get your hands on a gun that big, a blow or two on the crankshaft bolt with an air hammer (rentable) will break the seal that's locking things up. Don't worry, you won't damage anything by whacking it with the air hammer. Garages do this on a daily basis. You can even try a hard whack with a regular 16oz claw hammer, but don't miss, or you'll bend something expensive!!!!

If you don't have an air wrench or compressor, you can go to a nearby garage and ask them to buzz the bolt loose for you, then snug it up again, just enough for you to get home. Might cost you five or ten bucks or so, and the mechanic/garage may not even charge you if they don't have to put the car on the hoist. Worth a try, anyway.

The beauty of any impact gun -- air or electric -- is that because of how it works, the crankshaft and the engine itself will not move very much at all as you attack the bolt. This means that your careful TDC setting won't be disturbed, and you don't need to worry about trying to keep the crank from turning while you work.

Manual methods: Not as desirable, but if you have no access to the electric impact wrench or air tools, the only way
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With manual tools, a new problem arises: How to stop the engine from turning when you apply the necessary torque with a half-inch drive tommybar whose handle has been extended with a length of pipe. Just having the car in gear won't cut it. Jamming a big screwdriver into the teeth on the flywheel works sometimes, but it's a good way to risk tearing up the ring gear.

One possible serious problem with any manual approach to removing the crank bolt is damage to the engine mounts. Since you'll be applying a large amount of force over a large amount of time, you will end up pulling the engine in the direction of your efforts. Pull it enough and I'd wonder if you would run the risk of over-stressing the mounts. In the majority of cases, just pulling with all your might is futile, anyway. I'd try an impact gun, or the pulley-holding tools mentioned below before simply hauling on it with a breaker bar.

Luckily for us, Honda has already thought about this. Honda has used a number of pulley designs over the years, and  they have included features on the pulleys that are designed to receive pulley holding tools. These tools are available commercially, or are easily constructable by you.

The point of these tools is to keep the crank pulley still, not only for the obvious reason that you can't undo a bolt that won't keep still, but also so that the engine mounts are not stressed.

A warning here: It's my understanding that there are aftermarket shop manuals out there that suggest the use of a strap-type "belt wrench" to hold the pulley still. This is a bad idea. At least some Honda crank pulleys contain a rubber vibration-damper insert. A belt-type wrench can damage that.

For pulleys with a hexagonal center aperture
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For Hondas with a hex aperture in the pulley, the proper way is to use the tool pictured at the front of the shop manual. It's essentially a length of hexagonal pipe with a handle welded to it. It will fit into the hex hole in the pulley and allow a deep socket of the proper size to pass though and get hold of the bolt.
I don't know how many sizes of hex Honda used. The text below deals ONLY with the 50mm (2") size. Any advice from readers?

You can buy a tool, or you can make one.

Professionally made tools:

With the prevalence of Hondas on the road today, more and more tools outfits are offering pulley holders. They've become so mainstream that they're often readily available at consumer outlets like AutoZone, NAPA and Canadian Tire.

Here's one

And below are more:

Canadian Tire crank pulley tool These two came from Canadian Tire in Canada, photos courtesy of Curly. I saw identical ones at AutoZone, Kragen and Pep Boys in California.
The photo here shows both the hex tool on the left and the "ring of holes" tool on the right.
Apparently the blister packs have text on their back that indicates the models that they fit.

Cost is around $20~$30 each,
Another hex tool - different design
This tool is very close (if not identical) to the one shown in the autopart.com link above. The view here is from the side, so the hex opening is up and down.

Home-made tools:

You don't have to buy a tool though. If you're adventurous, you can roll your own...

Two posters, "jamieson" and "Curly" combine here to offer this clever version of the Honda "special tool".

Home-made crank pulley holder pic1
Home-made crank pulley holder pic2
Home-made crank pulley holder pic2
How It Was Done, from "jamieson":
"The local hardware store sells a 1 1/2" threaded plumbing adapter with a hex flange on one side of it. With a little bit of filing, the hex flange fits into the 50mm hex depression in the crankshaft pulley. Then I took a pipe wrench and cranked it down on the plumbing adapter threads sticking out of the crankshaft pulley. It works just like the Honda crankshaft pulley holder tool, only costs a lot

More detail from "Curly":
"It's not actually called a 2" fitting, but it is 2" across. ANY plumbing shop has them, just get the one with the largest internal thread, since your 19mm deep socket has to fit inside. You'll also need a 17 mm _DEEP_ socket for the motor mount. Make sure you have it ahead of time. I 'painted' the faces with jumbo marker, then used a bench grinder to grind off about 1/32" off all faces, so it would fit (same tool for first generation Odyssey), BTW.  "I also removed the outside threads, but that was for looks.
A buddy welded it to the steel bar, then blew the hole thru the bar for
the socket to go thru. "

This is simple enough that pretty much anybody with an acetylene torch or MIG welder should be able to stick these parts together for you and cut a hole in the middle of the bar. A muffler shop would be ideal for this. The hole in the middle has to be large enough to allow a socket to pass through.

Safety Steve's homemade tool
There's another way to make a tool from plumbing parts, one that doesn't require welding. Safety Steve shows us how:
"I liked the [other] homemade pulley tools you showcased, but I  don't like to weld in my garage. So I used all plumbing parts. Start with the 1.5" adapter, fit it into a tee, and add a short pipe for a handle. Removing the nut tightens the adapter into the tee hard enough so that it won't unscrew when you use it to tighten the pulley bolt, since it takes way more torque to get it off than what is required to tighten it. Still a cheap tool!"

For pulleys with a ring of holes around their center aperture
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Other, older Hondas have a ring of small holes around the central bolt hole, much like the bottom of an oil filter. Some have a protruding lip, some do not. Still, there are tools you can buy...

Canadian Tire crank pulley tool Yes, you've seen this picture before,
in the hex tools section above.
The one on the right is the one for the
"ring of holes" style of pulley.

Professional ring-of-holes pulley holder pic1 Professional ring-of-holes pulley holder pic1 jim beam supplied these pictures of an expensive professional tool.

It appears that your socket would fit through the large center lug on the tool, holding it centered while the pin locks in one of the perimeter holes.
Broken ring-of-holes pulley
What kind of damage can occur
if the wrong tool is used?
jim beam shows here, in this
dramatic photo.

 A tool may also be fabricated that consists of a long metal rod with two bolts installed at one end at right-angles to the rod. It looks sort of like a toothbrush with only two big bristles, one behind the other. You space the bristles so you can insert them into two of the pulley holes (skirting past the bolt in the middle), which locks the pulley in place, then brace the end on the ground as you try to undo (or tighten) the pulley bolt. Buying or fabricating a tool similar to the photos is preferable, though.

How to tighten the bolt back up again
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If you have a manual transmission car, it's a piece of cake. Just put the transmission in 1st gear, have a helper step on the foot brake (foot off the clutch), then operate that torque wrench. There'll be a bit of flex and spring in the driveline as you work, but not enough to matter.

If you have an automatic transmission, you'll be forced to use one of the pulley-holding methods described above. Unlike a manual, an automatic interposes no solid connection between flywheel and road wheels, so unless the pulley is forcibly held still somehow, the engine will simply turn round and round as you try to tighten the crank bolt.

A warning: It's my understanding that there are aftermarket shop manuals out there that suggest the use of a strap-type "belt wrench" to hold the pulley still. This is a bad idea. At least some Honda crank pulleys contain a rubber vibration-damper insert. A belt-type wrench can damage that.

Last updated: Feb06/08