Mercruiser 5.7 L circulating water pump HELP

[tacx]

Hi All

Hope someone can help me out. I have a 1996 Mercruiser 5.7 L Alpha 1 Serial # 0F777836 that needs a water pump. So I bought new one online from Mac Auto Supply. Their pump description shows a picture of the pump (see attached photo), but the pump I received is not exactly the same as shown in their description. The pumps are identical except for the fact that the pump they show has two water ports. one with two bolt holes and one with three bolt holes. The one I received only has two bolt holes at each port.

All the research I have done ( youtube,and other suppliers) shows the the pump with the three holes?

So my question is, is that third hole required or will the pump I received work?

I'm hoping to install it this weekend, but the boat is at the cottage which is 300 miles away in upper Michigan and I would hate to make the trip with a pump that wont work.

Again, the pumps are exactly the same except for the third hole at the left port?

I appreciate any help

Sorry cant upload a photo, here is a link to the pump I purchased

https://www.amazon.com/Circulating-B...gateway&sr=8-3

Tom

 

[tacx]

UPDATE, After more research it seems this extra hole is called a "water bypass hole". And, there seems to be confusion as to if its needed on all engines. There are two numbers associated with these pumps. MPR2232MN is the pump with the "water bypass hole". MPR2233MN does not have the bypass hole.

But I cannot find which pump my engine requires? None of the part lookup sites indicate which pump is needed nor mention any of these two numbers?

The pump Mercruiser gives as a part number is 850399-1

Any input is greatly appreciated

Tom

 

[alldodge]

Here is your motor

https://www.mercruiserparts.com/350-mag-alpha-4-bbl-gm-350-v-8-1996-1

Your part number is 46-8M0113734 (item 7) and is different then an automotive one. The marine water pump has brass bushings and inserts. If you have closed cooling then using an auto pump is ok, but not for open cooling

https://www.mercruiserparts.com/bam/subassembly/31770/1939/200