Pardon me Don S...

[magster65]

May I have your opinion on a couple things please?
I'm bringing home a 2006 240 Sundancer this weekend. I boat in the salt and since this boat was bought new for the lake... the 5.7 mag mpi is raw water cooled still. San Juan Manufacturing doesn't make a 'manifolds in' kit for this engine because of some computer / dry joint exhaust issues. The Merc kit is way more expensive. I can afford the San Juan kit now and think I should install that but since I spent my grocery money on the boat, wouldn't I be better off anyways buying stainless marine manifolds or headers in 6 or 7 years when the manifolds get rotted instead of the Merc. kit?
Apparently the Bravo 3 water pump is enough for the closed cooling... agree with that?
I moor for 9 months a year, I 'zinc' well (hang the old ones on a line off the side too) and the engine is flushed if it leaves the water for any reason. What do you think?
Thanks.

 

[Shaun78]

Re: Pardon me Don S...

Stainless exhaust is very expensive. I was quoted 2600 from a company in Australia. (Big Block though) Does hanging old zincs overboard on a line help? I never heard of that.

 

[achris]

Re: Pardon me Don S...

Stainless exhaust is very expensive. I was quoted 2600 from a company in Australia. (Big Block though) Does hanging old zincs overboard on a line help? I never heard of that.

The company in Australia that was building S/S exhaust manifolds stopped about 2 years ago. They had major problems with the manifolds cracking. Too much contrast between the cold side and the hot side for S/S.

The zinc hung over side will only help if the line used is conductive and attached to the engine block. If not connected, you might as well not bother, it won't help.

Chris.........

 

[Haut Medoc]

Re: Pardon me Don S...

The company in Australia that was building S/S exhaust manifolds stopped about 2 years ago. They had major problems with the manifolds cracking. Too much contrast between the cold side and the hot side for S/S.

The zinc hung over side will only help if the line used is conductive and attached to the engine block. If not connected, you might as well not bother, it won't help.

Chris.........

Hmmmm....
That's good to know, they still advertize on ebay.....

 

[Don S]

Re: Pardon me Don S...

You can get the full closed cooling system from Mercruiser cheaper than changing to SS exhaust manifolds. You also will need to change the ECM. They are programed different for the warmer engine temps.
Also when buying the Merc kit, you get a voucher for free replacement of the ECM where with the aftermarket kits you will need to purchace one seperatly. Which would be a $1500 additional charge on the aftermarket kits.
The Bravo raw water pump will work fine for the full closed system.

 

[newport dave]

Re: Pardon me Don S...

The bravo pump will be fine, but I believe Mercruiser says you need to add a second thru hull pump inlet on closed cooled models.

Dave

 

[HT32BSX115]

Re: Pardon me Don S...

I think you said that you're going to moor in salt for around 9 months out of the year?

It sounds like it is a fairly "new" boat so the "Zincs" are probably new and OEM (aluminum)

Be ABSOLUTELY SURE that you have the Mercathode system operating and set up properly! Have someone that is experienced set it up and after it's installed and working, have them come back a month or 2 later and check the operation.

Bravo III's (because of all the exposed stainless steel) have extraordinary galvanic corrosion mitigation requirements that ARE mitigated with the Mercathode.....but only if it's set up right. If it's set up wrong, the drive WILL corrode VERY quickly.


I prevent corrosion on my Bravo III by parking it in the garage


Cheers,

Rick

 

[magster65]

Re: Pardon me Don S...

I have the new boat home now. The drive only has a tiny little spot of corrosion and I can take care of that easily.
The cooling kit... I can't afford the Merc kit at this point and I may not for a while. I priced them out and the difference between the two is over $3500! There's no question the Merc is 'better' but the boat has emptied the bank and then some so this is the way it is
I picked up the San Juan kit... it can always be upgraded later if need be.
I'll leave the thermosthat the same temp and put the unrestricted riser gaskets in there... is there anything I'm missing here?
Thanks

 

[HT32BSX115]

Re: Pardon me Don S...

I don't remember how much $$ you said the Merc Kit would be.

I only paid about $700 for the complete San Juan kit for my 454. It pretty much included everything. I did have to pick up a couple of additional 3/4" copper elbows to make the hoses go where I wanted them to go without kinks or excessive bends.

Don't forget that you still need to change or reprogram the ECM or the engine may not run right. It's going to run somewhat hotter with the closed cooling and the fuel injection needs to be aware of this or it may make it run very rich.


Cheers,


Rick

 

[magster65]

Re: Pardon me Don S...

Don't forget that you still need to change or reprogram the ECM or the engine may not run right. It's going to run somewhat hotter with the closed cooling and the fuel injection needs to be aware of this or it may make it run very rich.


Cheers,


Rick

I'm not installing a hotter thermosthat. In theory the engine will run at the same temperature... in the real world I guess it may warm up a little. I find it hard to believe that just a few degrees will screw up the air/fuel ratio. If I was going from a 140 to a 192 I could see it maybe but I'm avoiding changing the operating temperature for that very reason. Having said that, I've never installed a San Juan kit on an MPI motor before though... I don't know how 'sensitive' this is.
The kits I've installed on carb'd engines haven't warranted a jetting change.
What does Don S. think about this I wonder?
On a side note... I asked Brad (owner) at San Juan about this and he said the ECM change is not required for this application.

 

[Don S]

Re: Pardon me Don S...

What does Don S. think about this I wonder?

Read my previous reply (#5) and you will know.

 

[magster65]

Re: Pardon me Don S...

I'll re-word it...
Why is the engine temperature going to rise to the point where the air/fuel mix is wrong if I use the same thermosthat?
What sort of temperature increase (ballpark) would warrant an ECM modification?

From what I can find, the 4.3 through 6.2 run; closed cooled 170, raw water cooled 160.

 

[newport dave]

Re: Pardon me Don S...

I think your talking about spending a lot of money for very little gain. Raw water cooled engine blocks last for 20 years or more, and if the only benefit would be preservation of the engine block, is it really worth it?? In my opinion, the conversion will (potenially) create more problems than it will solve.

Install a fresh water flush kit and flush after each use, your going to want to do this anyway to preserve the manifolds and risers, so why go through the expense and hassle of the conversion. Save your money for gas.

Dave

 

[magster65]

Re: Pardon me Don S...

I think your talking about spending a lot of money for very little gain. Raw water cooled engine blocks last for 20 years or more, and if the only benefit would be preservation of the engine block, is it really worth it?? In my opinion, the conversion will (potenially) create more problems than it will solve.

Install a fresh water flush kit and flush after each use, your going to want to do this anyway to preserve the manifolds and risers, so why go through the expense and hassle of the conversion. Save your money for gas.

Dave

I have the kit already and it wasn't that expensive.
I'm not a mechanic but it has been my hobby since I was a kid so there's no labor costs. This fwc conversion I've done 7 or 8 times now using the San Juan units and have had great results. This is a popular conversion here on the coast. This is my first mpi motor conversion though... so I'm wanting to get it right.

 

[magster65]

Re: Pardon me Don S...

You're quick with the smaty-pants answers Don. I'm in need of some decent consultation/conversation so bear with me. Can you please tell me why an ECM swap is required to adjust the air/fuel ratio of an engine that the only change is running a different coolant through the block?
Oh... I apologize for being as blunt as you .

 

[rodbolt]

Re: Pardon me Don S...

one of the benifits of the merc system is full closed cooling, means the only things that see salt water are the sea water pump,oil cooler,fuel cooler,heat exchanger and riser. most the merc kits,not all, cool the exhaust manifold with engine coolant. the second benifit is to allow the engine to run closer to 180 degrees which allows for more efficient combustion.
merc doesnt tell us why the ECU is so sensitive but I was told the ECU mapping for A/F, and ign timing as well as injection duration was different between the 2 ECU`s to increase fuel efficiency and emissions.
yes even in the marine world we have emission standards now.
next year rumour has it we will also see mandatory catalytic converters as well.
this should be fun.
but will your ECU work? dunno, never tried it.
try it and see
if it wont you may see spark knock on the scan tool, or you may see the plugs running rather rich.
I usually tend to just stick with merc stuff, if its wrong they get to pay not me.

 

[magster65]

Re: Pardon me Don S...

one of the benifits of the merc system is full closed cooling, means the only things that see salt water are the sea water pump,oil cooler,fuel cooler,heat exchanger and riser. most the merc kits,not all, cool the exhaust manifold with engine coolant. the second benifit is to allow the engine to run closer to 180 degrees which allows for more efficient combustion.
merc doesnt tell us why the ECU is so sensitive but I was told the ECU mapping for A/F, and ign timing as well as injection duration was different between the 2 ECU`s to increase fuel efficiency and emissions.
yes even in the marine world we have emission standards now.
next year rumour has it we will also see mandatory catalytic converters as well.
this should be fun.
but will your ECU work? dunno, never tried it.
try it and see
if it wont you may see spark knock on the scan tool, or you may see the plugs running rather rich.
I usually tend to just stick with merc stuff, if its wrong they get to pay not me.

Hey rodbolt
I've asked around locally too and have concluded what you just said is right. The different ECM is to increase the engines performance and reduce it's emissions at the same time... at the higher temperature. This is why I'm gonna' leave it running at 165 like it is now... the ECM I have is programmed for 165-ish.
I've been thinking out loud here... I value being able to bounce theories off other intelligent people.
Thanks everyone.

 

[rodbolt]

Re: Pardon me Don S...

wow I guess thats why I dodged the bounce
that being said, like I say, try it and see. you may or may not see any difference, if not I would go with a hotter t-stat and see again.
that engine is way happier at 170-180 than 140.
as long as spark knock doesnt become an issue.

but I am kinda with newport dave, unless it was FWC at birth its tough to justify the cost a few years into it.

 

[Robj]

Re: Pardon me Don S...

For engine longevity, they like to run around 180 degrees F. For performance, around 190 to 200 degrees F, 190 is the happy medium between longevity and performance. One of drawbacks with a raw water cooled engine is they are requirede to operate at cooler temperatures to prevent solids from forming on the cooling passages. I believe this is more of a problem with salt water, where the salt will form onto the cooling passages. Even though you will have a FWC engine, you may not be able to take advantage of the higher operating temperatures and benefits realized at those temperatures if you continue to run it with the existing t-stat.

I do not know anything about the ECM on these engines. But we have in the past used resistors connected in place of sensors on diesel engines to fool the ECM, and improve performance. Is something like this a possibility here?

Have a great day,

Rob.

 

[magster65]

Re: Pardon me Don S...

Yes... seen it first hand... hot salt water coolant will drastically shorten the lilfe of an engine. I guess that's why Merc uses a relatively cool 160 as the rwc t-stat temp. I wouldn't be able to sleep knowing I'm potentially harming a new 5.7 MAG MPI... tossing and turning... sweating...
I just want to keep the salt out of the block. There's no question the full kit is better but I can't afford it right now. I'll post my results although it may be a little bit... the weather still stinks up here and I have a full schedule for a while.
Cheers