To fresh water cool or raw water cool???

[tazrig]

I am installing 2 new Mercruiser Plus-Series 300 hp MPI complete power packages in a fully restored 1976 23 foot F-233c Formula. I will be operating the boat exclusively in salt water (new england area) and it will only be in the water on the days that I actually use it. I would like to be able to say that I will flush it with fresh water after each use but that probably won't happen. These engines will be used until they die (long term) so resale value is not an issue. I understand the basic differences between a (full system) fresh water cooled system and a raw water cooled system. What I don't understand is if it is really worth the extra $2k each engine to have the fresh water system installed or not. Does a fresh water system really add that much more life to the engine or make it run any better? If so, specifically why, how and how much longer does an average fresh water cooled motor last over a raw water cooled one? Also, what are the additional maintenance costs of a fresh water cooled system over a raw water cooled one? ie. does the heat exchanger have to be replaced and how often etc.? I realize it saves the manifolds from rotting although the elbows still need to be replaced every 4-5 years.

O.K. Guys have at it and thanks for the knowledge.

 

[Don S]

Re: To fresh water cool or raw water cool???

It makes the engine last longer (rust inside the cooling passages), MPI engines run better because they also run warmer. Manifolds last longer, and winterization with a full system is quick and easy.
The closed cooling systems also have a different ECM on the engine, so getting the cooling system now from the factory is also less expensive than changing your mind later.

 

[tazrig]

Re: To fresh water cool or raw water cool???

It makes the engine last longer (rust inside the cooling passages), MPI engines run better because they also run warmer. Manifolds last longer, and winterization with a full system is quick and easy.
The closed cooling systems also have a different ECM on the engine, so getting the cooling system now from the factory is also less expensive than changing your mind later.

Thanks Don, thats the kind of info I'm looking for. Question on the ECM. I already have the engines in their crates and would be adding on the cooling system. (from Mercruiser) Would i still need a new ECM and if so any idea what those mysterious black boxes sell for?

 

[Don S]

Re: To fresh water cool or raw water cool???

Contact your dealer, I have no idea what they use on the Plus engines, except that it's new.

 

[Tail_Gunner]

Re: To fresh water cool or raw water cool???

Ohh you may have some speed bumps ahead..a 76 is not wired for a 555 system..(merc efi type)

http://www.mercurymarine.com/repowe...ercruiser-products/plus-series/350-mpi-alpha/

Those engine's are already setup with 555...The quetion is how to wire the 555 into the old boat electrical grid.

I do not doubt Don's thought's on different ecm programming...Don is that from the mfg?

 

[MarkSee]

Re: To fresh water cool or raw water cool???

I am installing 2 new Mercruiser Plus-Series 300 hp MPI complete power packages...
O.K. Guys have at it and thanks for the knowledge.

This is going to be an interesting thread to follow but maybe you could clarify just a bit what it is you bought to clear up something.

The "Plus-series" is Mercury remanufactured and this could be what you bought which the below link shows 300 hp and will work with an alpha1-gear ratios 1.47 or 1.81
350 MPI Alpha | Mercury Marine

They also sell a "new" 300 hp 350 motor that lists only for a Bravo drive.
MerCruiser 5.0L, 350 MAG & 377 MAG | Mercury Marine

So is what you bought the reman units and you're hooking them to the alpha drives that were on the boat or are you getting new drives with the engines which makes it the "complete power package" term you mentioned?

thanks for helping me follow this

Mark

 

[Tail_Gunner]

Re: To fresh water cool or raw water cool???

This is going to be an interesting thread to follow but maybe you could clarify just a bit what it is you bought to clear up something.

The "Plus-series" is Mercury remanufactured and this could be what you bought which the below link shows 300 hp and will work with an alpha1-gear ratios 1.47 or 1.81
350 MPI Alpha | Mercury Marine

They also sell a "new" 300 hp 350 motor that lists only for a Bravo drive.
MerCruiser 5.0L, 350 MAG & 377 MAG | Mercury Marine

So is what you bought the reman units and you're hooking them to the alpha drives that were on the boat or are you getting new drives with the engines which makes it the "complete power package" term you mentioned?

thanks for helping me follow this

Mark

Your question could only be about shift interupt...gearing would play no part....Or let's see this could be intresting maybe timing curves...not.

 

[MarkSee]

Re: To fresh water cool or raw water cool???

Originally Posted by MarkSee
This is going to be an interesting thread to follow but maybe you could clarify just a bit what it is you bought to clear up something.

The "Plus-series" is Mercury remanufactured and this could be what you bought which the below link shows 300 hp and will work with an alpha1-gear ratios 1.47 or 1.81
350 MPI Alpha | Mercury Marine

They also sell a "new" 300 hp 350 motor that lists only for a Bravo drive.
MerCruiser 5.0L, 350 MAG & 377 MAG | Mercury Marine

So is what you bought the reman units and you're hooking them to the alpha drives that were on the boat or are you getting new drives with the engines which makes it the "complete power package" term you mentioned?

thanks for helping me follow this

Mark


Your question could only be about shift interupt...gearing would play no part....Or let's see this could be intresting maybe timing curves...not.

Huh?
Not quite sure what you're referring to in my post but my question was asking the OP on what exactly he bought so I could understand a little better what he was starting with and wanting to add fwc cooling to.

Mark

 

[tazrig]

Re: To fresh water cool or raw water cool???

Ohh you may have some speed bumps ahead..a 76 is not wired for a 555 system..(merc efi type)

350 MPI Alpha | Mercury Marine

Those engine's are already setup with 555...The quetion is how to wire the 555 into the old boat electrical grid.

I do not doubt Don's thought's on different ecm programming...Don is that from the mfg?

When I restored the boat I had them tear out all of the old wiring and replace it with new. I also put in all new VDO Viewline gauges a Raymarine MFD, a seperate Raymarine depth finder for when I wasn't using the MFD along with new rocker switches etc. You are correct about the incompatibility issue. It stems from the main wiring harness coming off of the engine. The old one had 12 pins (i think) and the new one has 14 or 15 (i think) either way you just need a new wiring harness coming off of the motors with the same pin configuration and plug all the wires at the other end into their respective gauge or alarm.

 

[tazrig]

Re: To fresh water cool or raw water cool???

This is going to be an interesting thread to follow but maybe you could clarify just a bit what it is you bought to clear up something.

The "Plus-series" is Mercury remanufactured and this could be what you bought which the below link shows 300 hp and will work with an alpha1-gear ratios 1.47 or 1.81
350 MPI Alpha | Mercury Marine

They also sell a "new" 300 hp 350 motor that lists only for a Bravo drive.
MerCruiser 5.0L, 350 MAG & 377 MAG | Mercury Marine

So is what you bought the reman units and you're hooking them to the alpha drives that were on the boat or are you getting new drives with the engines which makes it the "complete power package" term you mentioned?

thanks for helping me follow this

Mark

Mark,

To answer your question I bought two 300 hp MPI Plus-Series engines, 2 new transom assemblies and 2 new Alpha 1 generation 2 drives with the 1.47 ratio. You can buy the 300 hp MPI new or remanufactured (Plus-Series) each with the option of getting either an alpha or bravo drive system. What you saw on the "new engine" spec sheet about the bravo was referring to how you drain the motor of water. If you get a bravo drive with either engine there is a "three point drain system" that you can do by hand. The alpha drain point system is similar but there are more of them you have to remove to fully drain the block. 300 hp is the biggest engine you can put an alpha drive on and still have Mercruiser warranty it. I got a three year warranty on the engines thrown in from Mercury for buying 2 complete packages. The drives came with the standard 1 year warranty and I believe the transom assemblies are also a 1 year warranty.

 

[MarkSee]

Re: To fresh water cool or raw water cool???

Thanks for that. I did not pick up from just glancing over the page on Mercury's website that the PLUS was anything other than reman or you had a choice for the drive.

Getting the longer warranty makes it even sweeter.

Does seem to make a whole lotta sense like Don indicated to add the fwc at this point.

Mark

 

[Tail_Gunner]

Re: To fresh water cool or raw water cool???

When I restored the boat I had them tear out all of the old wiring and replace it with new. I also put in all new VDO Viewline gauges a Raymarine MFD, a seperate Raymarine depth finder for when I wasn't using the MFD along with new rocker switches etc. You are correct about the incompatibility issue. It stems from the main wiring harness coming off of the engine. The old one had 12 pins (i think) and the new one has 14 or 15 (i think) either way you just need a new wiring harness coming off of the motors with the same pin configuration and plug all the wires at the other end into their respective gauge or alarm.

Bit of a side note...Being that the boat is a go fast boat are you aware that's merc's 555 system is not tuneable at this this. In short if you mod the engine's your stuck. Mefi is a reprogramble ecu but would set you back 1500..Nice old boat sounds like a fun project, recently i picked a 217 intruder. The west coast version of a small go fast boat i am looking forward to updating the old girl..Just need to find a upper Bravo drive on the cheap.

 

[tazrig]

Re: To fresh water cool or raw water cool???

Bit of a side note...Being that the boat is a go fast boat are you aware that's merc's 555 system is not tuneable at this this. In short if you mod the engine's your stuck. Mefi is a reprogramble ecu but would set you back 1500..Nice old boat sounds like a fun project, recently i picked a 217 intruder. The west coast version of a small go fast boat i am looking forward to updating the old girl..Just need to find a upper Bravo drive on the cheap.

Not planning on modifying the motors. 600 hp pushing a 6,500 lb. boat is plenty for me. Do you know if you need the MEFI ECU to go with the FWC? Good luck with the Intruder. Nothing beats an old school heavy deep "V". Thats why I keep refurbishing my F-233c. I've had it for 25 years.

 

[Tail_Gunner]

Re: To fresh water cool or raw water cool???

Well Don said they do change the program for FWC i am sure your 555 is setup to run the engine's very well. The only issue i could see is the cold start protocol's. Call merc and find out. 555 and MEFI are both marine fuel inection type's very similar but differnt. At worst it may run a bit rich ..I think there just splitting hairs but who know's. The 555 are present already on the engine's are they not?

 

[tazrig]

Re: To fresh water cool or raw water cool???

Well Don said they do change the program for FWC i am sure your 555 is setup to run the engine's very well. The only issue i could see is the cold start protocol's. Call merc and find out. 555 and MEFI are both marine fuel inection type's very similar but differnt. At worst it may run a bit rich ..I think there just splitting hairs but who know's. The 555 are present already on the engine's are they not?

Yes the 555 come with the motors and the only way to get the FWC (at least with the Plus-Series) is to have it done after purchasing the engines. Although the 555 may not be fully tunable my mechanic tells me that when they make certain adjustments on the motors that have the 555 they just plug in a laptop to do things like adjust the idle or set the tachs etc. I'm guessing there must be some type of electronic switch in the 555 that can be flipped in order to make what ever adjustments need to be made for fwc but I will check with Mercury and get back to you to let you know for certain. Another thing my mechanic told me, unfortunately, is that the software is all proprietary with the 555 so only the dealer can work on it. Unlike many car computers.

 

[Don S]

Re: To fresh water cool or raw water cool???

Most dealers can't reprogram the 555 either, they replace them when going from raw to fresh water cooling.

 

[tazrig]

Re: To fresh water cool or raw water cool???

Most dealers can't reprogram the 555 either, they replace them when going from raw to fresh water cooling.

Once again you are correct sir... (spoken in my best Ed McMahon voice) I spoke with Mercury Remanufacturing today and they said the dealer would have to send them back the 555's and they would either "re-flash" and return them or simply exchange them for the required ECM's at no charge. They said I need closed cooling kit 864920A02 and that on my particular Plus-Series engines I would also remove the water pump from the alpha drive and replace it with sea pump kit 46-862914a06 in addition to drilling 2 ugly holes in the bottom of my just refurbished beautiful boat for sea water pick ups. Please tell me you know of some way in which to pull the sea water through the alpha drive instead of cutting holes in my hull!!!??? Also, am I correct in assuming I would be getting better quality buying the OEM Mercruiser parts listed above over just some after market? I noticed the Mercruiser kit is stainless steel, I haven't seen that on any of the other kits.

 

[Tail_Gunner]

Re: To fresh water cool or raw water cool???

Some good new there. IF i were you i would see if you could just get a credit for the 555 or two have them supply you with mefi ecu's. I am not for one minute going to talk about the quality of either product....Mefi is by far superior in terms of its programabilty and expansion..the cost delta is extroidenary.

If either of those two option's are not avaible the good new's is you did not get stuck with the cost burden of a reflash.

Module/Harness, Kit MEFI 4 Ram Jet 350 12499116

Damm the price went up a few hundred dollar's. There is the harness kit even include's OS sensor's The reliabilty is the same the reprograming is night and day the cost is less... the performance and econ will go up. And as alway's there is a down side...merc will void your warranty..:facepalm:

Oh well... Your still in better shape than before..

 

[Don S]

Re: To fresh water cool or raw water cool???

Once again you are correct sir... (spoken in my best Ed McMahon voice) I spoke with Mercury Remanufacturing today and they said the dealer would have to send them back the 555's and they would either "re-flash" and return them or simply exchange them for the required ECM's at no charge. They said I need closed cooling kit 864920A02 and that on my particular Plus-Series engines I would also remove the water pump from the alpha drive and replace it with sea pump kit 46-862914a06 in addition to drilling 2 ugly holes in the bottom of my just refurbished beautiful boat for sea water pick ups. Please tell me you know of some way in which to pull the sea water through the alpha drive instead of cutting holes in my hull!!!??? Also, am I correct in assuming I would be getting better quality buying the OEM Mercruiser parts listed above over just some after market? I noticed the Mercruiser kit is stainless steel, I haven't seen that on any of the other kits.

Glad to hear Merc will re-flash or replace your 555 ECM's at no charge. They are much better than the old outdated MEFI system. Better for troubleshooting and all.

The Alpha raw water pump does not put out enough volume and pressure to keep a full closed system cool. Thus the reason for the higher capacity pumps and separate pickups. Sorry, It's just how things are done. Merc does have a pickup that mounts on the transom. Takes smaller holes and easier to install than the ones through the bottom.
I'll look around and see if I can't find the info on them.

 

[tazrig]

Re: To fresh water cool or raw water cool???

The Alpha raw water pump does not put out enough volume and pressure to keep a full closed system cool. Thus the reason for the higher capacity pumps and separate pickups. Sorry, It's just how things are done. Merc does have a pickup that mounts on the transom. Takes smaller holes and easier to install than the ones through the bottom.
I'll look around and see if I can't find the info on them.[/QUOTE]

If you could dig up some info on transom mounted pickup that would be great! Thanks again for the help.