Years ago, 25 of 'em I think, I had to replace the broke timing belt on my Dad's '89 Integra (you know, you try to bring them up right but they gotta go their own way...) and the crankbolt was on there solid (like Excalibur!). It was a manual and the clutch wouldn't hold the torque. We were pressed for time and I didn't have any of those fancy crank holding tools (no jokes about hands...) so we put a cup of motor oil (Pennzoil 30 weight) in the number one cylinder, rotated the crank around for hydraulic lock, 1/2" breaker bar and a four foot cheater with the old man leaning on the cheater and me pounding on the breaker bar got it off. Had to be 500 pounds of torque. I ended up using that method on a few Hondas over the years. Just got to remember to pull the plug and spew the oil all over the engine compartment when you were done.
And oddly enough, the valves weren't bent!
After seeing this thread, I was pretty scared about the infamous Honda crank bolt. After reading a ton of threads on this topic, I decided to buy a Milwaukee 2767-20 1/2" electric impact (https://www.milwaukeetool.com/Products/Power-Tools/Fastening/Impact-Wrenches/2767-20) and a Lisle 77080 19mm high-mass socket (https://www.lislecorp.com/specialty-tools/19mm-harmonic-balancer-socket). With that combination, the crank bolt on our '05 Odyssey was loose in about 4 seconds. Wanted to put that out there in case someone else runs into the same issue as the original poster.
On a side note, I bought the Milwaukee impact just for this job, but I've been using it for removing lug nuts and have been really impressed with it so far. Although they're not a test for it's torque, there's a setting in reverse where once it breaks the nut free, the RPMs drop way down and it gently walks the nut off the bolt. The impact is completely overkill for every job I do (and it's heavy), but I like it a lot more than I expected to. I'm sure the mid-torque model with its smaller size and lighter weight is probably the better purchase for regular use, but I'm happy to have this one. And once every seven years (or 105k), it'll get to take a crank bolt off.
I’m pretty jealous of this result- but this episode did lead to us eventually lead to the gx460 purchase- so I’m good with it.
