The 465's we had were prone to water reversion with the wet pipes. Merc kept doing head and valve warrenty work in the first 30 hrs. I was surprised with the Merc guys from the factory coming to look everything over they could not figure out the wet exhaust problem.
Doller Offshore installed dry exhaust for us and never had another problem.
In fact the engines went somewhere over 400 hrs. with the owners that I sold the boat to and they knew nothing of how to take care or run a boat of that type.
I did remove the water pumps and went to crossovers and then they and the boat really came alive. Needed to reprop then.

I remember the owner had problems with reversion/water intusion and that is why he had the engines rebuilt.

If you want to find out a little more about the boat, use the search and do an advanced search with the screen name faceoff. He used to be on the board once in a while and made some postings with some upgrades and minor issues.

What is involved to swap to a dry exhaust? I've only seen a couple of boats with the dry exhaust, & I did wonder how they were cooled.

That is exactly what he told me, he had a reversion problem, & that is what led him to the rebuilds. He says he has had zero problems since the rebuild, less than 100 hours ago.
Is it a head problem, allowing the water intrusion? Or too much cam? I saw the specs, here on another thread, profile didn't look all that radical, but I didn't see what the overlap is.

I'm not sure what was causing the reversion for him. He chased the issue for while and then finally just did rebuilds. The early HP500's had reversion issues also and Merc ended up changing the Gil risers to a taller version.

There are still double walled with water in between the walls. The difference is where they dump. Mine tails are basically dry. The tails run all the way though the transom and dump water right at the end. Other systems run a bunge off the tails and dump it through a fitting on the transom.

I was just thinking, I do remember him telling me he had new Gil exhaust put on. So is this something that would mean, I need to remove & inspect the exhaust every couple of years? That certainly wouldn't be that big of deal, if it would help prevent losing an engine to water intrusion.

I had to replace my Gils on the Pantera at 8 years old. The manifolds had internal hairline cracks. He may have changed to the newer style HP500 risers which should eliminate any reversion.

Got any current engine pics???

Yes, as a matter of fact I do, he sent me some over the weekend. I'll fire them off to ya this evening when I get home....I'm at work right now....uhhhhh....working......yeah, working....

[QUOTE=Griff;2293724]I had to replace my Gils on the Pantera at 8 years old. The manifolds had internal hairline cracks. QUOTE]

Do you think any of that was due to saltwater use? I guess, in a broader context, what is the expected lifespan of an exhaust package?