Reversion ?

[MOBILEMERCMAN]

I'm actually thinking of dynoing the engine just to rule out the reversion theory and I would also like to see what kind of hp and torque the engine is making. I'm seeing rust in the ports after running on the trailer I looked up the riser with a flashlight and seen dropplets of water up in the riser, but I was thinking that was condensation.

I am not aware of any specific problems with your exhaust but, would like to share a thought. You say you saw what appeared to be condensation in the pipe. If you operate in cold water that could be the problem. Mercury encountered a condensation issue with the 420's and GIL's. They installed a diffuser ring between the tail piece and the manifold to catch the drops so they would burn off and not fall in the manifold and lead to valve issues. The HP 500's came with them as well.

#24 is the ring http://www.mercruiserparts.com/Show_...NIFOLD%2FELBOW

If you can not find any other explanation maybe this is something to look in to.

[ROGUE]

I am not aware of any specific problems with your exhaust but, would like to share a thought. You say you saw what appeared to be condensation in the pipe. If you operate in cold water that could be the problem. Mercury encountered a condensation issue with the 420's and GIL's. They installed a diffuser ring between the tail piece and the manifold to catch the drops so they would burn off and not fall in the manifold and lead to valve issues. The HP 500's came with them as well.

#24 is the ring http://www.mercruiserparts.com/Show_...NIFOLD%2FELBOW

If you can not find any other explanation maybe this is something to look in to.

Yes, I use the rings in my Gils and they do work to stop that. They called them anti-reversion rings but I think everyone argued the best they did was stop drip back. I dont think Ive ever seen them in any other exhaust system.

[eightsecmopar]

I don't think they make those for the Stainless Marine exhaust. I'm heading down to Florida in a couple of weeks, I was going to take a ride over to Stainless Marine and talk to Jerry to see if they have run into this problem before and what he recommends.

[MILD THUNDER]

Just re-read your first post, and saw that you said your tails dont introduce water, until the very end of the pipes, after they go the the transom. In that case, i think they are plenty long for the cam you are running. You are either getting condensation, or have a leak somewhere in my opinion.

[MILD THUNDER]

Just for the hell of it, you can let everything dry out, then run water thru the system. If you have freshwater flushes, that makes it easier. You cant really do it properly with earmuffs on the bravos. You want to hook the hose up to the system, where you can build up some psi in the system. Cap off the feed lines going to the exhaust manifolds. (if you have alot of city water psi, you might want to relieve a tad bit of psi out of the capped ends) Turn the water on, and let it sit under psi for a little bit. If you start seeing water droplets in the ports again, you have a leak in the engine. If no water droplets show up, re-connect the feed lines to the manifolds, and let it run thru them for a while. Check again for signs of water in the ports.

This might help eliminate the idea of a water leak.

[MOBILEMERCMAN]

I don't think they make those for the Stainless Marine exhaust. I'm heading down to Florida in a couple of weeks, I was going to take a ride over to Stainless Marine and talk to Jerry to see if they have run into this problem before and what he recommends.

Are you bringing the boat? Just for grins if it is condensation it will probably not show up in warm water.

[eightsecmopar]

No, I wish I was!

[eightsecmopar]

Thanks Joe I will give that a try. I have the heads off the engine now I'm thinking of having them pressure tested before I put everything back together. Even though they are new you never know.

[MILD THUNDER]

If you have a mark iv engine don't forget to use thread sealant on the head bolt threads.

[eightsecmopar]

I have Bow Tie blocks, the treads don't go into the water passages

[MILD THUNDER]

I have Bow Tie blocks, the treads don't go into the water passages

Good deal. Just checking.

[eightsecmopar]

Thanks to everyone for the help

[Ratickle]

Yes, I use the rings in my Gils and they do work to stop that. They called them anti-reversion rings but I think everyone argued the best they did was stop drip back. I dont think Ive ever seen them in any other exhaust system.

I think it was the backyard guys who started calling them that. It wasn't their purpose and they could not stop reversion. They were just for the drip-back as you say.

The more I think about this, how the heck could reversion be the issue if the water to the exhaust is not injected until the very end of the exhaust? Isn't that just too far?

[ROGUE]

I think it was the backyard guys who started calling them that. It wasn't their purpose and they could not stop reversion. They were just for the drip-back as you say.

The more I think about this, how the heck could reversion be the issue if the water to the exhaust is not injected until the very end of the exhaust? Isn't that just too far?

Yeah, pretty much, you would need one hell of a cam and idle at 500 to get it to pull back that far.

[OBNOXUS]

I think it was the backyard guys who started calling them that. It wasn't their purpose and they could not stop reversion. They were just for the drip-back as you say.

The more I think about this, how the heck could reversion be the issue if the water to the exhaust is not injected until the very end of the exhaust? Isn't that just too far?

ITS CONDENSATION !!!!!!

[MILD THUNDER]

I agree. before he posted the pic up and got to look at it, I was assuming he had a typical style wet exhaust with short tails. What he has is what I would condsider pretty much dry pipes. My stellings headers/tails pretty much dump water at the same spot, end of tails outside the boat. I run more aggressive cams, boat in cold water, no thermostats, lots of idling. No rust on valves.

Either way, I'd still be anal about checking everything over. Cold water dripping on hot exhaust valves is not good. Nor is enough moisture to cause rust to form on the valves or seats. Making up some turbulator plates to go between your tailpipe/riser, should be easy. They make them for the Gils, but havent seen them for the SM manifolds.

[ROGUE]

Heres a pic of them in place

[Ratickle]

Looks good......

[eightsecmopar]

I think one of my problems is the t-stat housing, the style that I'm using takes the raw water in and goes right to the manifolds. One thing I noticed the few times I did get out was the stat would open and close all the time. I think this is due to the cold Lake Mich water. The newer HP500 stlye t-stat housings has extra water outlets on the housing so you can plumb the warm water into the exhaust. I did find a Merc tech bulletin about this. I think this would help with the condensation problem. When I bought the boat it had cross overs on it and the engines never got up to tempurature, noticed that the oil had alot of condensation in it that's why I went back to the circulating pumps. I didn't think that it was reversion with the small cams that are in there but I wasn't sure. From what you guys are saying the condensation makes the most sense. I would still like to run the engines on the dyno just to see what kind of power they are making and just to rule out any leaks.

[eightsecmopar]

Link to article http://www.perfprotech.com/store/art...ling-tips.aspx

I'm currently using the cold manifold style.