How to find correct water pump kit

[SuppressedAR15]

Hi all. I have been enjoying and searching the forum for the past three weeks. So much help and info to be found here.

I have two questions for the masses:

1)How do I get a digital copy of the service manual for my motor/drive, and
2) how do I get the right part number/replacement part number for my drive's raw water pump?

In a nutshell, i have been battling an issue with the engine losing power after 25 minutes of running. While I will likely eventually post a separate thread with that issue (including every thing I have tried from reading scores of old posts found jerr), I manged to cook my impeller and water pump during some land-based testing sessions. (Yes, I read the service bulletin regarding the need to always have water running a tad too late )

I replaced the upper pump housing, impeller and gadkets, only to find that within 3 minutes in the water at the dock I re-melted the whole thing from a lack of water flow. During the attempt to see if it was flowing water, I did remove a water hose coming from the lower drive, and no water flowed at all.

I am uncertain why no water was flowing, as I had previously attached a garden hose to the copper tube in the upper drive unit, and had what appeared to be unrestricted water flow throughout the system and engine. I have since removed the risers, every water tube, the engine's water pump, and even the frost plugs looking for any obstruction.

My best guess is that the lower pump housing was bad, as it did have some areas that were a little funky.

The boat is a 20' Webbcraft, 1980 model year (built in 1979) with a 228 Mercruiser (305 engine). The chart in the sticky suggests it's a MC-1 drive. (Also called a Mercruiser 1 I think?)
serial number : 5471641

After searching the web, I seem to find conflicting model/part numbers for the pump that I need.
I would like to get a whole new kit, but even just knowing the individual part numbers would be helpful.

I will also attempt to attach a fee pics for reference.

Aside from needing the correct part numbers, any other guesses on the complete lack of water flow?

 

[Bt Doctur]

If the retainer under the water pump base has 4 slots you need a MR/Alpha1 water pump kit

 

[wahlejim]

Did you have the impeller installed in the correct direction (were the blades bent the correct way)? In the lower unit between the water intake holes and the water pump is there any blockage? There should be some screens by the intake holes to prevent large debris from entering and I couldnt tell if they were still intact. They could have broken and lodged themselves in between the holes and the water pump, restricting water flow.

 

[SuppressedAR15]

I twisted the shaft clockwise while installing the impeller, so I *think* they were going the right way.

I did not see any screens anywhere. I'm attaching pics for better visuals. If you mean the strainers at the base of the drive where the water originates from, those were totally clear.

BtDoc, are you referring to the round lock-nut holding the shaft in? If so, that has 4 lobes in it..

 

[Bt Doctur]

You did say you only dropped the lower so to install the lower you turn the prop backwards in fwd gear to line the splines up.
If the impeller was not lubed you could have reversed all the vanes. K-Y to your rescue there
Judging by the second pic, the water pump got wasted without water and is melted some. If the engine was started for as little as 15 seconds without water that will happen to the water pump.
Yes, that is a MR/Alpha lower and the base pictured is correct

 

[SuppressedAR15]

Ok, thank you for the info!
as the chart posted on the sticky says it should be a MC-1 drive, I guess I'm still confused, but I will order up the corredt parts based upon your knowledge.
-is there any issue with going with the Sierra stuff that sells for the $40 price range?

 

[Bt Doctur]

I use them and fine they work just as well

 

[Bt Doctur]

This will cover the drive but just the exploded pic is from a MC1 not the MR/Alpha. . Everything else goew with your lower
http://www.boatfix.com/merc/Servmanl/6/6B3R3.PDF#[0,{%22name%22:%22XYZ%22},-7,792,1]

 

[achris]

Upper and lower housings (as complete assemblies) for models MC1, R, MR and Alpha One are interchangeable. The serial number only refers to the upper.

In your case, you have an MC1 upper and an MR lower. You need to order water pump parts for an MR/Alpha One.

As you had a serious overheat and lack of water flow you need to check the water pocket cover, in the upper housing.

Hop this helps,

Chris. .....