Hi
is it possible to change the timing chain and sprocket without removing the oil pan on an hp500 ? Or there is a way to do it without removing the engin from the boat??

thanks

If you have "GOOD" access to under the front of engine you can loosen the oil pan bolts (more towards the front less further back) & GENTLY pry down on the front corners of the pan. This will allow you to remove the timing cover. You need to be real careful so is not to rip the one piece oil pan gasket. It's not easy, I've done it a couple of times with success.

if you do rip the oil pan gasket,just need to clean the rip real good and use a good rtv and put it back together,let it dry.then coat the ripped area again and install the cover.sometimes the rtv will have been put on the timing cover and the gasket will come w/ it,again,clean good,add rtv to everything and put it back together.
I like the ford diesel rtv,it can take some high pressure before it blows out.

i dont know if you have mark 4 or gen 5/6 motors, but i had to change timing chain covers and water pump set up on mark 4 motors, .
i cant get under my motors, so pulled them.
good luck.