Hey all, I just bought my first sterndrive boat, a 2000 Pursuit 2460 Denali with a Merc 5.7 EFI and a Bravo 3. It's time for risers and manifolds on the engine and I'll be doing it myself to save some dough and thoroughly familiarize myself with the new boat. I've turned wrenches as a hobby for years, so I'm not concerned about the work. It's not a go-fast boat, but you folks seem to be the most knowledgeable around on sterndrives, so I thought I'd post here.

I'm considering updating the motor to dry joint style manifolds and risers, but I have a few questions. Currently. it's a 1/2 closed system - coolant in the bloc but still raw water in manifolds and risers. Most of the system diagrams i see on dry joint systems are for full closed setups running coolant in the manifolds.

Is it still ok to run raw water through the dry joint manifolds? If it is, I'm guessing you plumb it the same way as the wet joint - a single raw water input in the bottom of the manifold and an appropriate restrictor style gasket at the dry joint? Any reason not to take this approach? I'd like to move to a full closed system in the future, but I want to get on the water for now and get to know the boat.

Current setup is manifold and 7* riser with no spacers. Am I correct that the dry joint manifold and the dry joint 7* would be (more or less) a direct replacement as far as fitting into the rubber exhaust boots?

Is the 14* short riser enough of an improvement in protection when backing down to warrant going that way instead of 7*? I've got the head space over the engine to clear the taller riser. Are any changes necessary to the rubber boots to make the 14* riser mate up?

I looked at doing this as well. I have twin Merc. 350s on my 2001 Formula 292. Bravo 1s.
I stuck with the wet joint due to having replacing the engines cost 2 winters ago, and not knowing 100% if the dry joints would fit 100%.

I'm about 80% sure they would fit just fine. My engines are open water cooled. The dry joint fit just moves the water transfer farther from the exhaust hole.
With correct plumbing, I don't see why you couldn't have a closed cooling for both on yours, assuming the heat exchanger is big enough.
I don't know if it's the same part for full or block only closed cooling systems.

Following along since next time I do mine (2025) I'd like to go dry joint if I can.

Some light reading:

https://www.perfprotech.com/blog/art...-joint-exhaust

https://www.perfprotech.com/blog/boa...nifolds-risers

Hey Sabr - yeah, I've read over their stuff a lot. I think the 7* dry joint may have come out after they wrote that - they only mention the 14*.

I've been looking at the merc diagram for the full closed cooling system and the manifolds use a center input on the bottom of the manifold for coolant. Then there's an output on the top of the manifold for coolant out, and an input to the riser for raw water in. My boat already uses a bottom center manifold for raw water feed, so I'm 99% sure I can do the same for the dry joint system. Right now I'm thinking raw water in at bottom center of manifold, open gaskets into the riser (no restrictions), and then it outputs through the exhaust. I think I can make it work, my biggest concern is the fit of the rubber elbows and whether or not to try the 14*

Good diagram here on this subject too:

https://www.perfprotech.com/blog/boa...m-flow-diagram

If you have 7° ones now, I don't see how 14° would fit... I assume if I bought dry manifolds and elbows (I have no risers in my setup) at 7 ° it would be a direct replacement.

It looks like the elbow never gets antifreeze in the diagrams as the hot water has to exit the boat somewhere. But keeping raw water out of the manifolds would be a win. That's what destroyed my original engines - 20 year old manifolds leaked into the valves and engine. not pretty. (Previous owner was a jackarse).

That's the drawing I've been looking at. No risers in my setup either, so I'd use blue coolant inlet near "f" for the raw water in - and put a plug at the red raw water input shown on the elbow.

What could go wrong? lol

I'd love to run coolant in the manifolds, but I need to take care of some other issues for now. I plan on having this one for a while, I've got time to convert it later. It's a trailered boat that sees 80% fresh water so I don't think its going to rot out before I get around to it.