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vlbob2
01-23-2010, 05:25 PM
Just finished installing new dart heads on sbc 1987 Classic 18. After all the effort and new heads, thinking about preserving them with antifreeze/water rather than the salt water I run in Delaware. I have fresh water flushed after each use, but on dissassembly could see the effects of salt! San Juan has a $900 heat exchanger kit for 87 sbc 350 chevy, but does anybody have experience with cooling block and exhaust manifolds closed system using the standard impeller in alpha 1 outdrive? I don't want to put a water intake hole in the boat and use separate volvo type harmonic balancer mounted pump. Rather than a hole in the boat I think I would rather just closed cool the block and saltwater cool the exhaust manifolds. Who has experience closed cooling :popcorn:using just the alpha 1 outdrive impeller? Thanks, Bob

gcarter
01-23-2010, 06:45 PM
Just finished installing new dart heads on sbc 1987 Classic 18. After all the effort and new heads, thinking about preserving them with antifreeze/water rather than the salt water I run in Delaware. I have fresh water flushed after each use, but on dissassembly could see the effects of salt! San Juan has a $900 heat exchanger kit for 87 sbc 350 chevy, but does anybody have experience with cooling block and exhaust manifolds closed system using the standard impeller in alpha 1 outdrive? I don't want to put a water intake hole in the boat and use separate volvo type harmonic balancer mounted pump. Rather than a hole in the boat I think I would rather just closed cool the block and saltwater cool the exhaust manifolds. Who has experience closed cooling :popcorn:using just the alpha 1 outdrive impeller? Thanks, Bob
The transom pickup is really the only solution. The Alpha pump just doesn't cut it. I got that direct from a San Juan engineer. Crank mounted pumps really rock and they're very easy to service.
I've done some threads on the subject;
http://www.donzi.net/forums/showthread.php?t=49388&page=2

http://www.donzi.net/forums/attachment.php?attachmentid=10375&d=1112068224

BigGrizzly
01-24-2010, 11:03 AM
Bad Tat has a full San Jaun system on it and it works well with his 502.

tmdog
01-24-2010, 11:03 AM
[QUOTE=vlbob2 Who has experience closed cooling ::using just the alpha 1 outdrive impeller? Thanks, Bob[/QUOTE]

I installed cc for eng. block only on a 1988 18'. I run a 180 stat w/ alpha pump only and cooling has not been a problem for the past 6 yrs. Heat exch. is a San Juan mounted low between stringers and front of eng. Extended running @5800 without issue.

BUIZILLA
01-24-2010, 11:08 AM
i'm not sure now adding cc to a seasoned salt engine is wise..

joseph m. hahnl
01-24-2010, 12:14 PM
does anybody have experience with cooling block and exhaust manifolds closed system using the standard impeller in alpha 1 outdrive? I would rather just closed cool the block and saltwater cool the exhaust manifolds. Who has experience closed cooling :popcorn:using just the alpha 1 outdrive impeller? Thanks, Bob


What your looking to do is add a 1/2 cooler.A full cooler will include the exhaust manifold in the system. I run a full cooler in my Minx with just the raw water pick up from the Alpha out drive. I haven't had any issues, other than taking it through a cool down after running WOT. I will run it at 1200Rpm for a short distance off plane. or throttle back to 3500 Rpm for a short,before coming off plane.This is just to dissipate the heat from the exhaust manifolds.
A 1/2 cooler would not have that effect as there isn't that extreme of heat source on the coolant like that, of the exhaust manifold set up. The only draw back to a 1/2 cooler is the manifolds are still at the mercy of the elements.
I have an ORCAhttp://www.orcamarine.com/news.html it has been very dependable. I did however, get mine used from another motor. and I had to modify the the thermostat neck to except a 3/4 barb fitting for the water pump by pass hose. Originally it had a 5/8 fitting. But as Orca Custom makes their coolers per application you can get all that done by the them.

http://orcamarine.thomasnet.com/Asset/501390.jpg





i'm not sure now adding cc to a seasoned salt engine is wise..

Been there done that, 6yrs and no trouble:yes:

silverghost
01-24-2010, 01:01 PM
I have had a "Monitor" 1/2 system on my BBC HP 500 since 1988. 4 sets of manifolds & risers , but engine is like new & I keep the boat in saltwater for 5 months each year! No need to add bigger raw water pump & extra water pick-up. In fact a full system with engine & manifolds should also work well without adding an on engine pump & pick-up.
It's almost never to late add a freshwater cooling system to an older engine.
You can stop the rust in it's tracks !
If old engine was used in saltwater. after putting-on the heatexchanger kit use a good heavy duty cooling system chemical flush. Follow diretions on flush.
Then add distilled water ony and run for a month or so & change-out water several times.
Finally add a high quality 50/50 antifreeze & distilled water..
Once you go with a freshwter cooling system you will never have another raw water cooled engine in saltwater !
If you run a carb engine use a 140*or 160*thermostat !
If you are running EFI engne always use stock temp thermostat. Using a lower tem t-stat in an EFI engine will cause your EFI computer to think your engine is always warming-up and fuel will be too rich & timing will stay retarded ! You performance will suffer as a result !

vlbob2
01-24-2010, 03:59 PM
I really appreciate your replies and although I have not decided yet, am looking for more of your experienced input. I do not want to put hole in boat or add a pump so your experiences are:popcorn: very valuable. I will let you know what I do and the results. Thanks again, Bob

silverghost
01-24-2010, 05:45 PM
Why not try a heat exchanger with your existing drive's pump; you can always add another pump & transom or bottom pick-up later if you feel you need it !

vlbob2
02-14-2010, 09:23 AM
Silverghost-(or anyone w/ block only cooling) When 1/2 cooling with front mounted heat exchanger, I'm trying to figure the plumbing. Seawater coming out of heat exchanger, do you "T" to underside of exhaust manifolds and let seawater circulate up internally to risers and out exhaust , or do you need to inject directly into top of risers as well? Bob

gcarter
02-14-2010, 09:48 AM
You TEE into the bottom of the two exhaust manifolds and it rises to the top and out the risers.

And while I'm sure you'll find plenty of anecdotal experiences of Alphas w/closed cooling using the drive pump, it won't work most of the time.
I suspect that if you go this route, you'll find it overheats (mainly in the summer) and there'll be nothing you can do to remedy the problem short of removing the heat exchanger.
If you don't mind, why are you so resistant to add a water pickup?
Your boat already has a lot of holes in the transom, including one really big one. It's just a hole. It''s easy to seal.
Take a look at the some of the 31 holes I've recently added to the transom of my TR project;

http://www.donzi.net/forums/attachment.php?attachmentid=53757&stc=1&d=1266101607

http://www.donzi.net/forums/attachment.php?attachmentid=53759&stc=1&d=1266101607

vlbob2
02-14-2010, 10:23 AM
You TEE into the bottom of the two exhaust manifolds and it rises to the top and out the risers.

And while I'm sure you'll find plenty of anecdotal experiences of Alphas w/closed cooling using the drive pump, it won't work most of the time.
I suspect that if you go this route, you'll find it overheats (mainly in the summer) and there'll be nothing you can do to remedy the problem short of removing the heat exchanger.
If you don't mind, why are you so resistant to add a water pickup?
Your boat already has a lot of holes in the transom, including one really big one. It's just a hole. It''s easy to seal.
Take a look at the some of the 31 holes I've recently added to the transom of my TR project;

http://www.donzi.net/forums/attachment.php?attachmentid=53757&stc=1&d=1266101607

http://www.donzi.net/forums/attachment.php?attachmentid=53759&stc=1&d=1266101607
George- I like your projects; you seem to have great attention to detail. If I add a transom pick-up and another pump, what do I do with existing pick-up and impeller in sterndrive? Also when I add another pump, I have another system to maintain including how to drive it as well as its impeller...the more systems, the more maintenance and the more prone to failure??? Bob

BigGrizzly
02-14-2010, 10:35 AM
Yes I T to the exhaust manifold.

gcarter
02-14-2010, 11:50 AM
George- I like your projects; you seem to have great attention to detail. If I add a transom pick-up and another pump, what do I do with existing pick-up and impeller in sterndrive? Also when I add another pump, I have another system to maintain including how to drive it as well as its impeller...the more systems, the more maintenance and the more prone to failure??? Bob

Bob, you simply remove the impellor, and its key from the housing in the Alpha drive. You also remove the hose from the bell housing (the bell shaped casting the outdrive is bolted to. In fact, you don't need to even remove the hose, just cut a section out of it. You also need to make a block off plate similar to the one in the picture above.
In my case, I'm adding a strainer, but if you didn't, the internal line could just run from the pickup to the pump you'll mount.
As far as pumps go, the crank mounted pump is the easiest to mount and doesn't add any complexity.
Good luck however you decide to go.

,

silverghost
02-14-2010, 12:22 PM
I agree~ T the raw water outlet comming from the heat exchanger to the lower front or rear of your center rise exhaust manifold with 1 " or 3/4" hose. 1" is best & what I have on my BB half system.
I agree that a full system that cools manifolds also would be a bit too much for the Alpha Drive built-in pump.
Just think about it~
If the alpha drive self-contained pump cooled the entire engine on raw (salt) water.
It should handle the block only on a 1/2 closed fresh water cooling system should it not ?
If it does not~
You need a better heat exchanger !
My "Monitor" brand exchanger is a four pass system !
What this means is the cooling tubes are basically folded in three spots on the ends by baffel plates.
If you un-folded my unit it would be almost 4' long !
In a heat exchanger it's all about surface contact area between the raw water and antfreeze.
The more surface area the better.
Single pass & twin pass units just don't do the job.
Years ago in the past single pass heat exchangers gave the closed cooling systems a bad name.
Engines would overheat etc.
Folks still remeber this today & avoid closed cooling.
With the better 3-4 pass units today, with smaller tubes, overheating is no longer an issue.
If you want to add a engine mouned pump ~
Do it .
The Johnson crank-mounted pumps are great.
A transom or bottom mounted pick-up is also great~
BUT I would bet you don't need it with a good quality 1/2 block-& head only system!
Systems are rated for horseower on both 1/2 and full cooling systems.
You Alpha pump might limit your cooling ability on a full system.(With Block & Exhaust Manifolds)
I have never see this happen on an engine-only system!
Just my experience !
I have been intalling these FWC systems since 1969 !

gcarter
02-14-2010, 12:35 PM
The problem w/the Alpha pump impellor is, it's so short from top to bottom (or front to back) and to make up for it and increase the volume in the space available, they increased the diameter of the pump w/longer vanes.
As the San Juan engineer told me, in warm water conditions, the vanes are so long and flexible, at times the vane tips don't touch the housing. If that happens, the volume it can pump is greatly reduced.
Then the problem cascades.
It might work, and it might not.
If you'll notice, no other pump impellor in the examples we have experience with looks like an Alpha impellor.

silverghost
02-14-2010, 01:06 PM
I agree with George on the Alpha pump Impeller vane issue.
The alpha pump was designed when most engines used in boats were way under 300 HP and ran to only 4500 RPM.
It is not a high- horse power, high RPM race drive.
The TRS was the Mercury race drive of this era.!
In any impeller pump the vanes moving away from the walls of the pump housing cavity can be an issue.
This is more true with the built-in Alpha drive pump than most others.
What causes this "vane-float" issue ?
The answer I have found is waterpump back-pressure.
The faster you go the more water your pump will put-out.
If you have a restricted engine water system the pump pressure will build-up to a point where the extra water the pump is pumping has no where to go. The back-pressure starts to build-up and soon the impeller vanes start to float in the pump cavity to releave this extra pressure.
To avoid this make sure you have no restrictions in any fititngs, hoses, thermostat/ bypass valve housings (caused by rust).
Use the largest water hoses possible.
In extreme cases you can add an extra transom mounted water outlet & valve to bleed away extra water & bypass part of your waterflow to the exhaust manifolds.
In fact in one application I put 1/2 the outlet water though the manifolds & bypassed the other 1/2 !
Always buy a high-quality Mercury Alpha Impeller.
Some aftermarket impellers are too soft.
Keep Alpha maximum RPM s to 4500--5000 max by using the proper pitch prop ! Pump impeller blades may "float" over 5000 RPM !
AND~
Replace Impellers every few years.

MOP
02-14-2010, 03:20 PM
Having been a certified marine for many years I need to put my 2 cents in, firstly temperature on our engines is very important to its life span. Raw water cooled running in salt water max Tstat temp should be 140 the problem with 140 is condensation build up in the engine. I am sure many if you have pulled the oil cap to see the mucky look inside, the condensation leads to rusting of internals valve springs for one which do break! I ran a 160 in my lightly worked 302 Ford 160 puts you on the edge of building salt deposits in the block but does away with the condensation issue, I have done so on several boats, all of which were flushed after running. Running the higher temp cuts down on cold stuck rings, adds more power and ups the overall efficiency as it bring the engines tolerances into spec. On closed cooling setups and engines run "strictly in fresh" water you should run 170-180, I run a 180 in my stroker motor as does Big Griz in his super charged Critter! Controlling pressure within the system to much and you end up blowing hoses left and right and having the head gaskets leak around the outer edges. I know of at least three fellows running 15psi pressure relief valves to alleviate the problem on their super charged engines. Most engines run too much pressure, head gaskets are not designed to hold a lot of water pressure. Automotive pressure caps on radiators are all under 20 psi, very few of our boats unless equipped with a pressure relief valve run under 30psi @ cruise and nearer to 60-70 at WOT. Griz reported on even higher pressures over 70mph! You guys that have sunk a substantial buck in your engines need to research this stuff properly, there is to much lack of knowledge out there your wallet depends on getting it right!

Below is a topic on sea water pressure these guys are running serious HP! A very worthwhile read!
http://forums.boatfreaks.org/showthread.php?t=7336&highlight=pressure+relief+ valves

breitstone
02-14-2010, 05:10 PM
I just purchased a classic 18 with a fried motor. I also purchased a 5.7 ltr (2001) engine from a fried boat. I am going to marry the two. The engine has FWC - 1/2 system. My boat has a 1986 alpha drive.

We are installing through hull intake to the raw water pump on the new motor. The alpha drive also has a lower unit pump. It is my understanding we need both because the lower unit pump cools the gears in the alpha drive. The engine mounted pump cools the heat exchanger. How do you marry the two pumps?

gcarter
02-14-2010, 05:37 PM
You don't need the drive pump as your forward motion will move all the water through the drive it needs. The pump also absorbs horse power. You do need to remove the hose in the bell housing and fabricate a block off plate for the inside of the gimbal housing where the hose fitting would have been.

joseph m. hahnl
02-14-2010, 06:09 PM
I just purchased a classic 18 with a fried motor. I also purchased a 5.7 ltr (2001) engine from a fried boat. I am going to marry the two. The engine has FWC - 1/2 system. My boat has a 1986 alpha drive.

We are installing through hull intake to the raw water pump on the new motor. The alpha drive also has a lower unit pump. It is my understanding we need both because the lower unit pump cools the gears in the alpha drive. The engine mounted pump cools the heat exchanger. How do you marry the two pumps?

If you want to keep them separate then feed the riser port #13 with the alpha pump. Feed the lower exhaust manifold port #5 or assembly(#15 through #17)with the dump from the heat exchanger, which is fed by the engine pump. Use the riser kit gasket. That allows the water to enter the riser from the exhaust manifold. One thing to keep in mind, there will be a lot of water in the exhaust with two pumps feeding it.

https://www.mercruiserparts.com/images/CRUISER/816596/18.png

mphatc
02-14-2010, 07:03 PM
I have a brand new Closed loop cooling system custom made for a 400 HP small block. This was made by Econmo kool and has never been installed. I Paid $700.00 wholesale for the whole set up amd will sell it now for $550.00

This was for my Corsican which rarely sees salt water and is always trailered. It to has aluminum heads, I had these coated internally and externally when new.

As long as you use a high quality anifreeze Ie; Not Prestone) and fill with distilled water, I'd also recommend 12 bottle of Redline water wetter you will arrest any on going corrosion and should not have any issues.

Mario L.

vlbob2
02-14-2010, 07:12 PM
If you want to keep them separate then feed the riser port #13 with the alpha pump. Feed the lower exhaust manifold port #5 or assembly(#15 through #17)with the dump from the heat exchanger, which is fed by the engine pump. Use the riser kit gasket. That allows the water to enter the riser from the exhaust manifold. One thing to keep in mind, there will be a lot of water in the exhaust with two pumps feeding it.

https://www.mercruiserparts.com/images/CRUISER/816596/18.png If you have 1/2 cooling heat exchanger, do you really think you need an extra pump and thru hull? Don't you think your alpha pump will cool the heat exchanger and exhaust manifolds? (Adding a pump & thru hull is exactly what I'm trying to avoid by cooling block only with heat exchanger) Bob

joseph m. hahnl
02-15-2010, 02:20 PM
If you have 1/2 cooling heat exchanger, do you really think you need an extra pump and thru hull? Don't you think your alpha pump will cool the heat exchanger and exhaust manifolds? (Adding a pump & thru hull is exactly what I'm trying to avoid by cooling block only with heat exchanger) Bob

I don't think you need the extra pump. As I said I have a full cooler with just the alpha impeller and I have no trouble with it.

A2VeeDub
02-15-2010, 02:54 PM
I have a half freshwater kit with just the alpha pump feeding it as well. Never had any issues with cooling up to this point. I generally don't run more than 3500-3700 for extended periods of time though.

I just did the conversion to the alpha this past summer. Prior I was running a seperate raw water with the thru hall pick up. I just liked the idea of less moving parts and hoses. Not to mention the chance to remove one more hole from the back of the boat.

I did have a few people tell me the alpha pump would not keep up. One guy told me he had no problems with his, so I gave it a try. Figured I still have all of the stuff for the other pump if I start running into temp problems.

BUIZILLA
02-15-2010, 03:36 PM
I just don't understand this Alpha cooling concerns...

they ran 454's with them for years...

people seemed overly stressed about using them on 350's

I don't think ANYBODY here has a run a mouse motor harder than me, and I never overheated one...

fogducker III
02-15-2010, 04:08 PM
I just don't understand this Alpha cooling concerns...

they ran 454's with them for years...

people seemed overly stressed about using them on 350's

I don't think ANYBODY here has a run a mouse motor harder than me, and I never overheated one...

+1

I ran a 383 stroker with an Alpha leg on a heavy 21' Cruisers Inc and ran the snot out of it and never had an issue......

gcarter
02-15-2010, 05:00 PM
I just don't understand this Alpha cooling concerns...

they ran 454's with them for years...

people seemed overly stressed about using them on 350's

I don't think ANYBODY here has a run a mouse motor harder than me, and I never overheated one...

Jim, it's not a matter of cooling the engine, it's a matter of cooling the engine w/a heat exchanger. It takes more water to do so due to the loss of efficiency transferring heat through the secondary medium.

BUIZILLA
02-15-2010, 06:29 PM
I would think with a 1/2 system the stock pump would be sufficient

I can see the concern on a full system however

MOP
02-16-2010, 07:47 AM
The only time you will see an Alpha pump fall a bit short is with S/S headers, the headers run hot at low idle speeds. The run hot on the tops due to the dump holes being a little to big so they don't stay full, as soon as you raise the RPM they are fine. You guys need to quit being "Old Wives" and go boating!