Oil Seal Housing Stuck

[Ferris11]

2006 F90TLR 4 stroke
This past fall when I drained my lower unit I found a few ounces of water in the oil. I pressure tested it and found bubbles escaping through the lower unit drive shaft which indicated to me that the oil seals under the oil seal housing were damaged. The water pump came off OK but when I got to the the oil seal housing underneath it is solidly stuck on. I went online and the consensus was that this housing is a real pain to get off especially if you are trying to save the housing and to preserve the mating surface. Since the motor is 18 years old I am OK with installing everything new from the water pump to the 2 oil seals that are below the oil seal housing.
My question is how much force can I apply to that metal housing to break it free from its mating surface? Would heat or penetrating solvents sprayed around the gasket help to loosen the housing?
Would a hammer work just as well if I wasn't expecting to save the metal housing?

[panasonic]

Get your self a couple of small pry bars from harbor freight. Pry on both sides at the same time. Should be a little notch on each side of the housing for prying up on. Trick is not to break the Lower unit itself that the pry bar will be pushing against. A couple of small pieces of 1/8" flat bar to lay across the webs in the casting to spread the load while prying. You may make break the seal housing getting it out. Goodluck

[Ferris11]

Panasonic, thanks for responding. I did try what you recommended but that housing was not budging and I was afraid of ruining the mating surface below the housing. I scoured the internet and found one picture of a guy removing that housing by inserting a punch into each hole of the housing and basically pounding it off by spinning the housing off of the drive shaft. I had to make sure I didn't damage the threads in the mating surface of the lower unit and I did destroy the aluminum housing but it did come off in one piece. I am now able to replace the seals in a new housing, replace the water pump and my lower unit will be good to go. I usually service my water pump every 2 years but I will now be replacing the gasket under the oil seal housing at the same time as preventative maintenance.

[panasonic]

Well you got it done without damage to the rest of the Lower Unit....so that's a win!