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Boatwrench
07-27-2009, 12:42 AM
I'm new to this forum so I just thought I would throw this out there to get some other opinions. I own an 82 Sweet 16 with a Merc 260 and alpha drive. I'm going through the engine right now and I was wondering if it would be a good idea to get rid of the circulation pump and mount up a crossover cooling system with a bypass. I need to keep the thermostat because the boat will spend most of it's time in Tahoe where a thermostat is a necessity. I'm getting rid of the stock log manifolds and putting on some Glenwood logs and it just seems crazy to keep the old 260 style cooling system. The steering is also going to get changed over to a Sea star system so the only thing running off the engine will be the alternator.

VetteLT193
07-27-2009, 06:29 AM
I like the crossovers because it's one less thing to go wrong.

If you get the stainless marine kit, it should come with a T-Stat with holes drilled in it. If you don't get the Stainless kit, just make sure you drill the 3 holes out in the T Stat. I think they are 1/8 inch holes, but that is just memory, so double check that.

gcarter
07-27-2009, 06:59 AM
The raw water pump in an Alpha is a very wimpy pump at best.
Just to be sure of proper flow, some sort of circ pump is a good thing.
There're alternatives, like a SM transom pickup and a crank driven raw water pump. With such a setup, then a crossover will work well.

MOP
07-27-2009, 07:11 AM
If you follow Georges advice make sure you get a crank pump for a small block, the big block pump which I bought makes way to much pressure you will need a pressure relief valve. Without the pressure relief valve your head gaskets will start to weep, head gaskets do not hold up very long with high prssure. Phil

BigGrizzly
07-28-2009, 10:40 AM
I can actually say that the circ pump is a good thing gives evener engine temps. plus does flow a little when the alpha pump dies.

silverghost
07-30-2009, 11:49 PM
I would keep the stock circ pump.
Now I will show my age~
In the mid 60s when higher performance engines from GM (Chevy) started going into new boats and no circ pumps being put on by marine engine buiders there was a flood of heat related performance issues.
Outfits like OSCO & BARR used to offer water pump block-off plates and T inlet pipes in their "Marine onversion Kits" they marketed in the 50s & 60s.
The resulting heat related performance issues were :
Over heating
pinging from hot combustion chamber pre-ignition
combustion chambers in cyl heads cracking.
Blown head gaskets.
At GM's insistance
Mrcruiser, Crusader, etc got tgether with GM engineers to redesign the cooling systems on their marine use V8 engines.
GM found that the stock auto circulator was a benefit to more even cooling and prevented combustion chamber heat related issues.
CIrculator pumps with SS shafts & pump impeller wheels & back covers, with better seals, were designed to upgrade the conventional automotive circ pumps for the harsh mrine environment.
GM told the marine engine builders that they would not stand behind any of their engines used for marine use without a circulator pump and bypass type thermostat systems with pessure relief valves!
The marine engine industry totally redesigned their cooling systems based on GM designs.
The industry never looked back !
You would be surprised how much internal engine water flow that these pumps provide.
Remember that the cylinder head combustion chamber area is the hottest part of any engine. These circ pumps keep a constant flow of water in this head area even if the thermostat is closed and engine is running slowly !
The result is a far better runing engine that will last longer !
That circ pump is there for a good many reasons!
Just My Opinion !
Brad Hunter

Lenny
07-31-2009, 09:10 AM
I say toss the circ pump, SSM crossover kit (c/w drilled T-stat holes). That is how mine are.

BigGrizzly
07-31-2009, 06:14 PM
I am with Mr Hunter, I remember the 50 and 60s.

gcarter
07-31-2009, 06:26 PM
Randy, I do too.
But if you want a crossover, ya gotta have plenty of water and you're not gonna get it w/an Alpha w/o some help.