I just removed mine recently. I also tried the prying with 2 screwdrivers, pliers and heat.
None of these worked for me and I think the heat thing is the riskiest of these 3 because of the close proximity of the plastic chain tensioner for the oil pump. One could easily damage that if too much flame got to it.

I also read the grinding advise thing, but there was no way I was going to grind on that ring because of the stone and metal grit that could get into the engine. Even with rags stuffed in there I don't like the chances. Does not take much grit to score bearings and other critical engine parts.

I was prepared to buy the $184 dollar tool if I had to.

My ring was " hanging on for dear life" . I got it off by removing that upper aluminum piece . I was then able to get a decent angle to gently tap a very small screwdriver type chisel between the seal ring and the crank and that moved it easily. It still would not slide so I used prying with screwdrivers and a power steering pully puller to get it off the rest of the way.

Working on mechanical things would get boring without a little challenge now and then.

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Diesel-guy