cutting the Gordian Nut

[Dash01]

Lots of issues regarding the 36mm collar nut that holds the harmonic disk at the front of the engine: This nut must be removed before the timing chain, guide rail, seal, etc. can be changed.

Although attached with ~317 ft. lbs. of torque, many here have reported that it takes MUCH more torque than that to remove it--perhaps several times as much torque. One guy even said that both he and his friend could not budge the nut even with both hanging from a 5' breaker bar, which suggests ~1,500-2,000 ft lbs. of torque was insufficient to loosen the nut. Others have reported that the crankshaft securing tool may be twisted or mangled in the attempt to remove the big nut. Use of an impact wrench necessitates ~12" of clearance behind (or removal of) the radiator and AC condensor, which would entail de-pressurizing and then recharging the AC system.

The 36mm nut costs about ~$5, and probably the old one should not be re-used anyway.

So, why not just cut off the old one with a Dremel Tool and/or nut splitter? On reasssembly, clean the threads of the crankshaft, add Loctite, and then torque the nut to 317 ft. lb. spec. while securing the crankshaft by jamming a cold chisel into the flywheel teeth.

Your thoughts?

[skr]

it will come off if u pull hard enough. i did it with the engine off, with a "special tool" bolted to the balancers hub . i broke a hex key on it (22 mm on m21) but eventualy it came off. (1.5 meters bar helped).
cutting it/drilling it out doesn't rrealy seam doable as it's a M18 12-9 class bolt. it other words it's extremly hard, or they don't come much harder than this.
oh, and if you loctite it, it ain't coming off again

[E34-520iSE]

The pulley bolt on my M20 engine was EXTREMELY tight. I only got it loose using a chunky 3/4" drive socket, a fixed type 3/4"drive bar and 5 foot of scaffolding tube slid over the top of the drive bar. I had someone in the car holding the brake pedal(car in 1st gear) and me outside giving the scoffolding bar some major heave ho! It slackened in the end, and I only needed a few inches of clearance to get the socket on and the bar up past the top of the engine. You may need to remove the bonnet first. I dunno if this will help you but it may help someone with an M20.

HTH,

Shaun

[SnakeyesTx]

You can't get a 1/2" drive breaker bar and impact socket in there and just bump it with the starter till it breaks loose? It's always worked for me on just about any motor I've ever worked on so far. Also.. 317 ft/lbs?! WTF? you'd think the stud would break or the threads would strip first.

I guess if worse comes to worse you could always borrow a "Torque multiplier" type wratchet good up to 15000 ft/lbs.

[Dash01]

~317 ft. lbs. or torque is just what's called for in putting the 36 mm nut ON the car. After ~17 years, it's sometimes pretty well fried on there, so some guys have reported that REMOVAL has effectively meant sometimes well above ~1,000+ ft. lbs. to pry the nut OFF.

Since some folks say never to use hardware twice, I am wondering about just cutting the old 36 mm nut off, then replaceing it with new nut at proper torque spec.

[DaveVoorhis]

I think the trick will be finding something that will cut that hard little bastard.

[nizmainiac]

i had no problem getting mine off my m20 engine, i just put it in 4th gear and put the handbrake on, you could use a short piece of scafford tube on the breaker bar, that might help

[Felixdacat]

I agree with snakeyes. I have done the same thing for many a car. Haven't had any problems.

[calmloki]

Ditto dat on using the starter and a breaker bar - worked for me on a M20 and a M30.

[genphreak]

Been there, done that. Cutting it is hell, but possible. And potentially messy, you will damage the crankshaft's threads without a doubt.

Just use some scaffold pipe, go buy a half inch breaker bar and a 1/2 37mm socket. Spray some penetrant on the night before JIC it can help. If the car is still running, do it 2 weeks before as the heat/cool cycles might help the penetrant penetrate!

It's a fine machine thread so won't let go until you cut it in two. My mate and I still hung off the thing with a breaker bar to no avail when it was 2/3 through. We were cutting extremely carefully, the pressure was hard on the thread and did not release incrementally as we thought it might.

WHen we did mine, (which is an auto and had the head off so the motor was moving freely). I had no other way to get the nut off. It pays to use your nut in situations like these.

Don't cut. Its tough. Its a bastard but its harder and more dangerous to cut it. If manual you can chock the car and heave.

Q: Why did God make automatic cars in the first place? Were we not lazy enough for him?

A: He wanted to cause the complete downfall of the human race.

(You can probably guess that I dislike auto trannies)

Nick