Intake Manifold Problems - Help!

[propless]

Out boating this afternoon and started hearing what appeared to be an exhaust gasket giving way (no major deal, but a pain none the less). Upon looking further, it is the exhaust manifold gasket?
I'm no rocket scientist, but in all my years of boating, never have I lost an exhaust manifold gasket and I'm at a lost at what causes the intake manifold gasket to fail.
Three questions:
1. Is this a major issue and should I have a pro replace this and look deeper into the failure?
2. Or is this not that uncommon, and should I be able to replace this? Any torque requirements or what outs that I should avoid?
3. If I mark the distributor before pulling it out, should I not be able to drop it back in without having to reset everything?
Boat was running great, no issues to report. It is an Indmar 454, Edelbrock aluminum manifold w/850 Holley - nothing very fancy.
As always - thanks for the help and comments.

[lovemyultra]

20 ft lbs on the intake bolts in a specific sequence you can get out of any manual. you should be able to drop the dist back in but it never goes that way just mark the rotor, get it close, and reset the timing to specs no biggie GOOD LUCK DJ

[propless]

DJ-
Thank you!
Not from Maryland are you?

[Tahiti Day Cruiser]

Hi propless,
Actually I had something similar happen to my 350 chevy small block. Had my boat on the lake for about 10 minutes when all of the sudden I notice some smoke coming from the engine compartment. Killed the engine immediately but unfortuneatly damage had already been done. First thing checked the water pump and realized this is where the failure happened. The pump went out causing the engine to overheat and ended up cracking the exhaust manifold on both sides, and also the flaps which regulate the exhaust and do not allow water to get back in the engine. If your engine got really hot then you may have done more than just blown a gasket (let's hope not). Anyhow to change the exhaust manifold is not all that difficult but once your doing that you should check the flaps and other gaskets to make sure there's nothing else wrong there. Probably the easiest check is to see if there is any water in your oil. If so then for sure there is something more than just the manifolds. The flaps are a bit more difficult to change but can be done with a little patience and the right tools. Maybe you should get the service manual for your particular boat, the Seloc brand of marine manuals are full of information and very helpfull.
Good luck http://free.***boat.net/ubb/wink.gif
Good luck http://free.***boat.net/ubb/wink.gif

[propless]

Changed out the intake manifold gasket and put everything back together. Boat fired up and sounded great so timing must be online, oil looks good. The real test will be this weekend in the water and fine tune the timing - appreciate the help and the comments people sent. Your folks ar great!

[propless]

Try this again - "you folks are great"