Closed cooling

[smokediver]

Hey guys , I would like to get a few opinions on converting my 502 mag mpi to closed cooling. It has about 250 hours , a 2001 model. I remember Tidbarts motor locking up on a trip and I believe it was in part due to saltwater eating away at the intake manifold. My plan is to do a long trip in fresh water , pull the intake and check for corrosion and then to install a half closed cooling system. I am sure I will have to replace the coolant a few times but hopefully it will hold any corrosion in check. Any thoughts ?

[BUIZILLA]

i'm getting ready to do the exact same thing on a 502-415 myself.. within a week or so

we'll talk

[Morgan's Cloud]

The stock Merc kit for that engine is quite a simple and clean installation and works fine.
I think most of the issues raised will be how much flushing / time will be needed to completely clear all of the salt in the pores of the iron out .

If you have the stock cast iron exhausts , that's what you have to worry about. I replaced mine with Hi-Teks at 67 hours , about 2 years on them since new , and they were just starting to show salt penetration in the metal and an iffy riser gasket.

FWC is great to have .

[gcarter]

On larger, more powerful engines, 1/2 systems are the only way to go. Otherwise the HE gets pretty big.
I really like electric circ pumps. Meziere makes some nice large capacity for both engine mounted and remote.
The brand I used is from Monitor Products http://www.monitorpro.com/products/c....php?c=20&f=14
built in Brooksville, FL.
This is a cheaper place to buy the Monitor systems: https://www.perfprotech.com/high-per.../category/1511 .
If you buy from these folks, they are drop shipped from Monitor here in FL.

There's a bunch of others. I like the Monitor system because it includes a HE mounted thermostat and the engine cooling runs wide open all the time.

[smokediver]

Thanks for the info George. I was also looking at a kit from center state engine in brooksville. Maybe the same one. They are asking just under 800 for a complete half kit. I just did a half ditch run from Franklin lock to the fish camp and back. I put in on the east side of the lock so it was all fresh water. I am sure there will always be some residual but hopefully 5 hours of runtime is a good start. Jim , give me a ring at 239-777-2631 and let me know how your conversion goes !

[BUIZILLA]

I haven't bought anything yet, still shopping

[JayZ]

I used the kit George mentioned. Very stable temps at around 165. Pretty straight forward install but mine was on a new engine. The H.E. is pretty big...

[Tidbart]

Just as a point of information the weak point isn't the iron it is the aluminum intake manifold.

[smokediver]

I remember you mentioning that Bob. I put a set of EMI manifolds on and am now turning my efforts to check the bottom of the intake. Hopefully it's still in good shape !!

[Morgan's Cloud]

Just as a point of information the weak point isn't the iron it is the aluminum intake manifold.

Can anyone explain why a manufacturer of marine engines would use dissimilar metals in its construction , aluminum nonetheless , and NOT sell it as FWC only from the factory ?

(I've wondered this for a long time )

[joseph m. hahnl]

Can anyone explain why a manufacturer of marine engines would use dissimilar metals in its construction , aluminum nonetheless , and NOT sell it as FWC only from the factory ?

(I've wondered this for a long time )

I suspect it's optional because not every boat is going to run in the salt. You don't really need closed cooling if your running in fresh water. I think it's more the boat factory that fails to install the cooler package. My old 350 Mag was a closed cooling conversion. worked great for years. That full cooler is now on the Phoenix 400. The intake manifold is still alive and I'm using it in my 350 Mag RHR build for my cruiser. That build also has a full cooler and I'm changing from 3.0 logs to 4.0 center outlets with stainless risers.

[gcarter]

Can anyone explain why a manufacturer of marine engines would use dissimilar metals in its construction , aluminum nonetheless , and NOT sell it as FWC only from the factory ?

(I've wondered this for a long time )

Steve, I think the days of that are over. W/the advent of all aluminum, injected, catalyzed engines, closed cooling is required for a lot of reasons.
Let's all get used to coolers, newer controls, higher operating temps, etc.

[mattyboy]

Steve, I think the days of that are over. W/the advent of all aluminum, injected, catalyzed engines, closed cooling is required for a lot of reasons.
Let's all get used to coolers, newer controls, higher operating temps, etc.

Most of the VP offerings have FW cooling they seem to embrace technology VVT, computer control , automatic trim control, cruise control

[Morgan's Cloud]

The idea that not every boat is going to run in salt water has crossed my mind a few times before . The problem is that only 3% of all the water on earth is fresh water .

Just as a reference , when we ordered the 502Mag for the Mag 25 we already knew we wanted the FWC option and the supplier thought it was an excellent idea although he never mentioned anything about an aluminum intake .
It was probably more to do with the fact that he knew we were going to take care of it , especially considering that we're in some seriously salty water over here .

When I ordered the Volvo 5.7Gi for the St T I wanted FWC but I didn't think it was going to fit in the very limited space under the engine box . The supplier said that he ordered all of his engines with FWC whether the customer specified it or not.
I think I can recall him saying something about the aluminum intake manifold that Volvo used as being a big part of the reason.
Incidentally , it is mentioned in the voluminous Volvo owner's manual that they use a special alloy manifold of their design on that engine , but there's no mention of such a critter in the 502 handbook.

Otherwise, I think you're right George, and Matty , as the engines continue to evolve into ever more high performance and efficiency realms they'll end up using a lot of dissimilar metal parts , thus necessitating fresh water cooling .

[joseph m. hahnl]

The idea that not every boat is going to run in salt water has crossed my mind a few times before . The problem is that only 3% of all the water on earth is fresh water .

Just as a reference , when we ordered the 502Mag for the Mag 25 we already knew we wanted the FWC option and the supplier thought it was an excellent idea although he never mentioned anything about an aluminum intake .
It was probably more to do with the fact that he knew we were going to take care of it , especially considering that we're in some seriously salty water over here .

When I ordered the Volvo 5.7Gi for the St T I wanted FWC but I didn't think it was going to fit in the very limited space under the engine box . The supplier said that he ordered all of his engines with FWC whether the customer specified it or not.
I think I can recall him saying something about the aluminum intake manifold that Volvo used as being a big part of the reason.
Incidentally , it is mentioned in the voluminous Volvo owner's manual that they use a special alloy manifold of their design on that engine , but there's no mention of such a critter in the 502 handbook.

Otherwise, I think you're right George, and Matty , as the engines continue to evolve into ever more high performance and efficiency realms they'll end up using a lot of dissimilar metal parts , thus necessitating fresh water cooling .

It seems like 95% of runabouts run on that mere 3%