Water Pump Help - 1984 Alpha

[mceagle]

[FONT=&quot] [/FONT]Some History – I have been fighting a high RPM overheat issue with my 1984 5.7L, Alpha drive set up in my sea ray. With the great help and suggestions from this forum’s users, the cause has been narrowed down to air ingestion. I have replaced the ¾” pain in the a** hose and now to the water pump. I have pulled out the Sierra parts and have the OEM parts on hand, including the pump base. As I was removing the Sierra part, I thought that I had identified the cause of the ingestion – a small channel running from the outside of the base to the inside. I was surprised to find that the Mercruiser part has the same feature. For the countless times that I have replaced water pumps, I have never noticed this channel. So, being paranoid and tired of this project that has included bellows, shift cable, U-joints, water pocket, gimbal bearing and trip senders. I am turning to the forum experts to ask about the purpose of this feature, and, if there is something that goes into this part. See the photo for a better description. Thanks!

 

[Bt Doctur]

page 3B-14.. that groove belongs there. the pump base and gasket are the 2 biggest culprits in seeing an air bubble stream because that's the low pressure side(suction) of the pump. Over-tightening the bolts is the other operator induced failure.

 

[Rick Stephens]

Looks to me like that slot is an escape port should the water outlet from the pump get blocked. That slot is below the water pump seal and above the oil seal for the lower gear case. If the pump blows out that way it would just escape back into water instead of into the gear case.

Like the Doctur said, if you are sucking air it will be right at the pump.

Rick

 

[Bt Doctur]

http://www.boatfix.com/merc/Servmanl/6/6B3R3.PDF

 

[Eric 3.7LX Alpha 1]

Be real careful with those water pocket cover bolts. They have been known to snap off and will require drilling and tapping. I wouldn't mess with it unless necessary.

 

[mceagle]

Be real careful with those water pocket cover bolts. They have been known to snap off and will require drilling and tapping. I wouldn't mess with it unless necessary.

Thanks - Surprisingly they came out easily. I had read posts about this issue so I used heathy doses of PB Blaster and let it sit overnight.

 

[mceagle]

http://www.boatfix.com/merc/Servmanl/6/6B3R3.PDF

Thank you much for the advice and espeically for the link to the manual!

 

[mceagle]

Looks to me like that slot is an escape port should the water outlet from the pump get blocked. That slot is below the water pump seal and above the oil seal for the lower gear case. If the pump blows out that way it would just escape back into water instead of into the gear case.

Like the Doctur said, if you are sucking air it will be right at the pump.

Rick

Thanks, Rick - Certainly appreciate the advice and insight!

 

[mceagle]

I know that this is off-topic and perhaps needs to be in another thread but - I am looking for the correct bell housing hinge pin torque specs for the drive. I have read everything from 60 to 115 ft lbs in different manuals and postings. Thanks!

 

[mceagle]

Murphy is alive and well tonight - While installing my new, expensive OEM water pump, including base, I snapped off the screw while torqueing to spec. Not sure if there is enough protruding out of the base to do an extraction - In case there isn't, is this screw absolutely necessary? Dangnabit!

 

[Rick Stephens]

That screw supports the whole end of the pump housing. I would say it is likely to fail the gasket eventually without it. Doggonit, that ain't right. You have to at least try with a good small vice grip to pull it out. If not, that's a $20ish base that needs replacin'. Not worth an overheat at just the wrong moment.

I can't imagine using a torque wrench on the water pump. Wrist pounds is plenty good enough. That screw, the one with the plastic threads, doesn't even need more than a socket on a screwdriver handle. Wish Merc wouldn't get so fancy in their manual. Watch achris's video. He describes it best.

 

[Bt Doctur]

where are you finding the spec for the screw? the 3 nuts do.

 

[Bt Doctur]

where are you finding the spec for the screw? the 3 nuts do.30 inch pounds is like 2 fingers with a 1/4 inch drive