Reedy .21 back plate removal

[Bogan Thunder]

I got this engine used recently and it's gummed up with nitro fuel oil just like a bunch of other used engines i bought i did use a heat gun on it and put some fuel through it and it's slowly turning over i want to remove the back plate and it's stuck in there good, i have the piston positioned at TDC i could grab a pair of pliers and wiggle it off and scratch up the side back plate but i would rather remove it without marking it and having it look like crap...any tips how to remove it?
I did try large pliers but the back plate still wouldn't budge.

 

[smokinwheel]

Soak it in something like WD40? If you have an ultrasonic cleaner putting it in there while soaking might be better.
Just a thought.

 

[Bogan Thunder]

soaking in WD probably won't loosen it or even get in between the case and back plate, i really need a tool that can fit around the edge of the back plate to turn it i guess i will find something to remove it without wrecking it.
I have some 5mm flat bar aluminum i might dremel two pieces to shape for each side of the back plate edge then i grab it better with large pliers.
Another option that i will try tomorrow is put engine in the vise with two small blocks of pine wood to clamp onto the back plate then just turn the engine case to loosen back plate.

 

[jeepfreak1972]

soaking in WD probably won't loosen it or even get in between the case and back plate, i really need a tool that can fit around the edge of the back plate to turn it i guess i will find something to remove it without wrecking it.
I have some 5mm flat bar aluminum i might dremel two pieces to shape for each side of the back plate edge then i grab it better with large pliers.
Another option that i will try tomorrow is put engine in the vise with two small blocks of pine wood to clamp onto the back plate then just turn the engine case to loosen back plate.

Kroil will creep into one millionth of an inch. Worth a try. Best penetrant I've tried out of many.

 

[Bogan Thunder]

Kroil will creep into one millionth of an inch. Worth a try. Best penetrant I've tried out of many.

this back plate is fused in like no other back plate i have experienced plus there is a o-ring inside there as well, i tried multi-grips on it and it didn't budge and the multi-grips put a notch on both sides of the back plate...maybe heating the case more might loosen it enough.

Edit:
I wasn't applying enough heat around the case last time but this time i got it up to 60 degrees and the back plate rotated without too much force using multi-grips pliers i should i known better to apply more heat to get it off, anyway it looks a bit nasty in there.