Horizons vs. raw water cooled

T

Troubadour

New Member
Jul 30, 2008
52
Boston, MA
Boat Info
270AJ
Engines
6.2MX BIII
So my new boat has a horizon engine and I know it's supposed to be better for durability... Is there any drawbacks when it comes to maint.? I would imagine the weakest link is now the heat exchanger and all those little copper tubes. How do these differ from the new Seacore engines? Is the seacore just new marketing and the minor revisions? Just curious!

- Brian
 
Yes, I believe so (Seacore). There aren't any real gotcha's to the fresh water cooled engines. The heat exchangers are not supposed to cause any problems that I am aware of.

The fuel coolers (version 3) were causing some problems. They are box-shaped. I don't know if your boat has them or not.
 
I have a 2004 5.0 - B3 combo on my 240. I recently converted the raw water system to a closed cooling. I am not sure in your application if the exhaust manifolds and risers are on the closed coolant loop, mine are. After having both raw and closed, I would never go back to raw. Other than eliminating the concern for me of saltwater in the block, manifold, and risers, the big advantage IS the whole system runs at a more consistent temp. With a temp gun, I have monitored inlet and outlet. Instead of putting 70 degree seawater into the block, I put in 135 degree coolant and out comes 160 degree coolant. A 25 degree swing versus, 90-100 shock to the engine block. I thought it was BS when I purchased the closed cooling system, but they insisted that my GPH would improve. YES it did. At cruising speed, I dropped from 10.5 to 9.6 at the same RPM of 3,250.

Yes, the heat exchanger in a "corrode-able" item, but would you rather replace a heater exchanger OR replace the block, manifold and/or risers? Even with my new system, I still freshwater flush after each use and run salt-a-way through the system. According to Mercruiser, they recommend a flush for either RWC or closed systems. After a season worth of use in saltwater, I cracked the covers off my exchanger last weekend - those tubes look like brand new.

As for SeaCore - I can't comment - simply don't know enough about the system.

Enjoy the new boat.

tginz
 
Troub,

My understanding is that the SeaCore units include all of the features of the Horizons plus the anodized outdrive and transom assembly. If you have a SeaCore engine/drive, Merc. labels the flame arrestor shroud and outdrive as such. Check Mercs. website and see. I seem to remember seeing the first SeaCore equipped SeaRays late spring 2007.
 
tginz said:
I have a 2004 5.0 - B3 combo on my 240. I recently converted the raw water system to a closed cooling. I am not sure in your application if the exhaust manifolds and risers are on the closed coolant loop, mine are. After having both raw and closed, I would never go back to raw. Other than eliminating the concern for me of saltwater in the block, manifold, and risers, the big advantage IS the whole system runs at a more consistent temp. With a temp gun, I have monitored inlet and outlet. Instead of putting 70 degree seawater into the block, I put in 135 degree coolant and out comes 160 degree coolant. A 25 degree swing versus, 90-100 shock to the engine block. I thought it was BS when I purchased the closed cooling system, but they insisted that my GPH would improve. YES it did. At cruising speed, I dropped from 10.5 to 9.6 at the same RPM of 3,250.

Yes, the heat exchanger in a "corrode-able" item, but would you rather replace a heater exchanger OR replace the block, manifold and/or risers? Even with my new system, I still freshwater flush after each use and run salt-a-way through the system. According to Mercruiser, they recommend a flush for either RWC or closed systems. After a season worth of use in saltwater, I cracked the covers off my exchanger last weekend - those tubes look like brand new.

As for SeaCore - I can't comment - simply don't know enough about the system.

Enjoy the new boat.

tginz
Click to expand...

Alright, maybe we should start a new thread on this, but you've got to spill the beans on how you did this. :smt038
 
Lots of info available on the web. Many vendors have complete kits that are complete to the clamps and bolts and instructions . Perfprotech, boatersworld, San Juan Engineering, Marineengineparts, and many others come to mind.

I do have some experience since my boat was raw when I bought it. The engine was overheated due to a bad H2O pump on the raw water side. So, going to closed cooling was a no brainer.

If you can change a radiator hose, you can install a kit.

DG
 
Last edited:
tginz,
I believe you already had a raw water pump on the engine with a B3 drive, correct? How about the raw water, where does it come from, the outdrive or do you have a separate thru-hull.
I'm not sure what DG is thinking, but I imagine some people don't worry about the water until they get into this thing.
BTW, my 1980 had Factory FWC with separate water pickup thru the hull. Also a second factory hole that is plugged. Check your hull before starting you may have a hole you can easily put a pickup in.
 
To answer your question - I only water pick-up I have is through my B-3. I have an after-market freshwater cooling system manufactured by Monitor Products, Inc. in Brooksville, FLA. They build the FWC systems for Merc and Volvo. They also offer their own aftermarket. The plumbing is absolutely identical to the Mercury factory FWC system but to avoid the secondary thru-hull intake, they simply increase the size of the heat exchanger. As far as I can tell it is double the volume of the stock mercury exchanger. If you are tight on space it could be a problem but it is NO bigger than the "square" engine dimensions
I love the system. It cools incredibly. I even tested it by hooking the hose to a hot/cold mix faucet at my shop. At 110 degree water intake, I was never varied off 160 degree coolant temp. for 10 minutes at 2000 rpms.

I would highly recommend the Monitor Products Systems. The quality is outstanding and frankly seems better an Merc AND the whole system (I have their premium system which puts block, manifolds, & risers on freshwater coolant) is $1,265.00 versus Merc.'s $3,400.00 which does not include cutting in an additional thru-hull. They also keep the temp @ or around 160 which does not require changing the ECM. Mercury runs their FWC at 170+ which requires a different ECM for proper fuel mixture.
 
Sorry, I should have included this before.....


Here's a link to Monitor: http://www.monitorpro.com/index.php

They used to locate up here in New York and relocated to Florida several years ago. I had my local Mercury guy recommended them.....Hope Merc does not find out. I should clarify my previous statement - Monitor does not make FWC system for Mercury and Volvo - their folks told me they build the Heat Exchangers for them and many others in the marine engine business. Their people and facility are top notch. They are about 6 miles off I75 on the West Coast of Florida.
 
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