Have an '86 Donzi Minx w/ Alpha drive. Just replaced the old 260 with a Vortec 350 w/ exhaust upgrade to Stainless Marine Hi-Torque system. Also went to full closed cooling to save the aluminum manifolds (f'n salt water). I believe the Alpha raw water pump isn't cutting it (at idle the tops of the stainless risers are very hot). If I go to a crank driven water pump is it possible to still use the pick-up in the alpha drive?

yes, just be sure to remove the impeller from the drive and only the impeller. you could also use the same seawater pump as the bravo.

I had the same problem when I went to closed cooling. I had to go to through hull water pickup and raw water pump to get adaquate water for cooling the exchanger.

I have the 1/2 system and the stat reads 180 steady .The exh. manifold is cool but the ss risers are hot to the touch. Been running in fresh for the last 3 yrs. I thought it is normal. Am I wrong?? Just running off the Alpha pump. EMI long risers and dumps at end.

the alpha drive does not pump enough water for that motor.install a raw water pump with a transom mount pick up.disconnect the hose going from the drive to the pump.block off the nipple at the transom where the water from the drive comes out.this wiil allow the water from the drive to cool only the drive and the water will dump thru the prop.under no circumstances take out the impeller out of the drive you need to keep it cool.the draw back is when flushing you need to install ears on the drive so you don't burn out the impeller.and run a hose to your flush on the motor.
good luck

Some Alphas have a high volume internal water pump from the factory. I'm not sure what the Mercruiser part number for the pump is, but it was used on the 1986-1987 Alphas that were paired with the 454 (these motors did NOT have factory water pumps installed).

I believe Sierra, and several other aftermarket companies make this water pump as well. I'm not 100% that it will solve your overheating problems, but I'm sure it won't hurt!

- Paul

I do have an alpha with the 454 an on a long blast I do notice the temp goes up a little nothing dangerous I wonder if a diffrent pump would help.


Thanks

under the advice of mercury marine, the company that makes the unit, this is how you install an engine with a bravo water pump into a boat with an alpha drive. it is also outlined in the instructions that come with the mercury marine closed cooling system. the water passing the nosecone is what cools the drive. but dont take my word for it call mercury.

Thanks everyone for the help. I am planning to install a Jabsco type crank driven pump rated for big blocks and closed cooled systems along with a thru-hull pick-up. I understand the crank pump should work fine at rpm's below 5300. Is there any other reason to go the added expense of the bravo type belt driven pump?

no, you are going to be fine with the jabsco pump