Sea Water pump required for closed coolong system ?

[cmk245]

I'm sure this has been answered before, but cannot find info on this subject.
I have a 5.7 engine from a 1987 boat with closed cooling full, system (San Juan MC305) Full System. It was using ONLY the stern drive pump for water.
I have read several posts on having to use engine driven raw water pump for full closed system, and re-route hose from drive to overboard to cool drive.
I HAVE a complete raw water pump setup with all the brackets, pulleys, and belt. But I would have to purchase the correct hoses to make this work.

The heat exchanger is the large SJE model (25"x5"). I spoke to SJE, and they said that the exchanger was designed to work with the stock Alpha drives water pump. So I am confused on if I should leave it as ,or install a thru-hull and strainer in my hull and use the belt driven pump.....

Engine is out of the boat now, and NOW would be the time to do this. I DO NOT want to find out after install that it overheats at idle., due to not enough water flow.....

ANY Help will be Appreciated......
Thanks,Charlie

 

[Bt Doctur]

Almost all "full systems" will not work with the outdrive impeller.A full system should use an engine driven one using atleast 1 1/4 hose

 

[cmk245]

Thanks for your input.
So now I just need info on correct way to re-route water hose from outdrive, to bypass engine
It appears that the SJE units are aftermarket, and maybe were OK, to get by using stock drive pump.I never had this engine in my boat, so I don't know how well it worked. But I agree about using belt driven pump with larger hose. Just wanted some input on the subject.
Thanks......

 

[cmk245]

Something else I must consider if going with Belt driven pump is that I also have a LOWER mounted P/S pimp, and the adjusting bracket attaches to the same set of holes that I would use for the Sea water pump bracket.
Did Mercruiser have a setup with BOTH Lower P/S pump AND Sea water pump on front of engine? Sure would like to see one to copy.......

 

[thumpar]

You leave the drive impeller the same but cut the hose. It needs the cooling. You can cut the hose and block off point it comes into the transom. Then you install a thru-hull pickup with sea strainer.

 

[tpenfield]

If SJE says it will work as is, I would try it.

 

[cruzn]

Mercruiser always recommended a belt driven pump on v-8's, especially older ones that preceded the larger floppy- vane drive pumps that are used today.
This is especially true when using a "complete" system (exhaust manifolds included).
Is the kit you have from Merc? Don't know where or how to find it but Merc did offer an auxiliary pump kit - maybe if you or someone could find the part number it would include installation instructions and a parts list. I think that without it you will be operating on the fine edge - the slightest little blockage, hiccup and there will be overheating and possible damage

 

[cmk245]

The Heat exchanger I have has San Juan Eng. stamped in it, including their T-stat housing. so I believe that it was a retrofit system and I have heard that Merc. did not use San Juan Systems. BUT I have, a OLDER, pre-alpha? parts manual that shows "Closed cooling system" parts list, which show a "Transom" mounted water intake part, (mounted along side the outdrive) The closed system was on the motor when I bought it (with P/S), and PO upgraded to 502 Big Block.

I have the Sea Water pump and parts , They are from a 5.7 Inboard motor, which did not use a, P/S pump.....

I still need a photo or info to see how to mount , the Belt driven pump , WITH the LOWER P/S pump, as adjusting brackets conflict. Can't use HIGH mounted P/S pump as heat exchanger is too wide 25". Alt is under exchanger, and P/S pump is below that.
Now I know why they went to Serp. Belt (no adjustment brackets needed, only Idler) cheaper, for them maybe.....

I believe I may just install the motor just to see where the Seacock will have to mounted, so it does not interfere with anything.(or I could measure, I believe)

ALOT of work, in and out. I was thinking just to install the pump on motor anyway, and then leave belt off to see how motor runs with just the sterndrive pump.
A, PITA but could plumb-in later?

Anyway I plan to "Dry Fit" the raw water pump And, P/S pump on motor (which is in my garage) and see if this is even doable......
Will report on this to all...... If it does not fit together, I will sell Raw water pump, and use the outdrives pump.

Thanks for everybody's Input......

 

[alldodge]

Well SJE designed the system to work with the alpha drive pump, so I agree with Ted and just use what you have.

If you go with belt drive pump, I suggest go get a serpentine belt and change your pulley's. Bottom right (Bravo) routing

 

[HT32BSX115]

The closed system was on the motor when I bought it (with P/S), and PO upgraded to 502 Big Block.

The PO didn't likely put a 502 on an Alpha though.

I helped a neighbor with his 5.7 closed cooled engine replacement plus Alpha drive several years ago.

He tried it with the drive mounted pump and it just could not run at very high power settings for any length of time without the temp climbing.

He ended up installing the engine mounted Bravo pump.

 

[cmk245]

PO bought a Bravo 3 to go with the 502....He had to change EVERYTHING...even went with thru hull exhaust.........I don't think Alpha would last a hour with that guy. He Blew up the 502 about a week after installing it....502 in a 25ft. Fishing boat !!!!!!... I though he might want his engine back, but he got another boat I heard.....
Not sure on PO answers about how well the engine ran with stock pump in leg, he told me he just wanted more power....It did come with brand new Merc. (center rise) manifolds and ext. and risers, though, It is a Jasper Marine 350, I know maybe not so good I hear.... Low hours anyway.....

STILL NOT in the boat, YET........
..

I may have NO choice with the belt driven pump I have, was on a 1995 5.7 Inboard and bracket will NOT allow power steering adjusting brace to mount (uses same holes in block). I can mount either the P/S pump OR Sea Water pump, but NOT both, on this setup . And I NEED the P/S pump........

I have parts catalogs for both, the 260 (1982) and 260R (1987) and Brackets ARE different . So I would have to find OLD style Sea water pump and bracket to even start this, I only wanted to try this because I had a Sea Water pump to use, just not this one.....I whole lot more then I thought would work.......Buying more pulleys ,etc....

I will have that VERY Heavy Heat Exchanger cleaned out by Radiator shop and go with Sterndrive pump, in NEW SEI Outdrive. I have. Damn thing weighs as much as exhaust manifold.. (I'm 65 so to me their Heavy) Worked over 40 years on Cars and Trucks, and maybe about 20 on boats........mostly outboard's....

Will have to see how it works, and go from there.......Maybe I will find correct bracket to make this work., TOO Long out of the water.

Thanks to everyone for their input's.

 

[thumpar]

Where is your power steering pump mounted? Mine is port side somewhat low and the raw water pump is starboard side low.

 

[cmk245]

No Title

Sound the same as mine, I will attach a photo of a engine (NOT MINE) with the Alt. and P/S setup I have. , The photo does not have closed cooling ,but the brackets are the same as I have.
You can see where the problem is with attaching Sea Water pump to block with P/S adjusting bracket attaches.
Can you reply of photo of what setup you have, as I would like to see how it is. I need V-belt setup.........

 

[thumpar]

No Title

This is how mine is setup. It is not mine but same locations.

 

[cmk245]

Yeah, You have TOP mounted P/S pump. I have to use LOWER mounted pump because of width of heat exchanger, It states in SJE kit to use ONLY with lower P/S pump, but nothing about ADDING raw water pump. If I spent ALOT and purchased all new pulleys and brackets, I could Maybe go with Serp. belt..

But not in the cards right now. My engine came with SJE kit already installed. So unless I run across a deal on brackets and pulleys, I will use what I have.
I cannot find any photos of setup like mine with added water pump, All have smaller exchanger.....Mine is 25" wide........ I have another photo of WIDE exchanger setup , but not clear in photo, on setup.for added pump, I will attach. Photo., maybe someone can comment on it......

 

[thumpar]

I see now. The only other thing I can thing of that doesn't require too much work would be to have someone fab up a new adjustment bracket bolted where the other bolts on the port side are. You can just try to run it and see. If it runs hot then worry about it.

 

[cmk245]

Since this motor is New to my boat, I plan to do just that, run it as it is and see how it goes. If it runs too hot, will have to plan on up fit of Belt. driven pump.Just would be a whole lot easier to do before dropping in........

Have a Safe and Happy New Year.......and Thanks for everybody's Input.......

 

[FreeBeeTony]

Hope these pics help.........you can see the belt driven raw water pump in the second picture.

 

[cmk245]

Thanks,FreeBeeTony, But your P/S pump is mounted high, I you look at the photos of the Red motor I posted is like what I have, Lower pump.
I'll find a photo somewhere.......They DID make it.