Unidentified Drain Plug

[leegoldring]

Replacing water pump in 1969 1C and after removing lower unit, noticed what looks like a 3/8 brass drain plug just below the top flange at the front of the housing. After pulling the lower housing, I see the plug leads to the cavity just in front of the lower shift shaft and bushing. Not sure of the purpose of this drain plug. Also, I see an oil vent screw on both sides of the drive housing. When filling from bottom fill hole, should I expect to see oil coming out from both vent holes in drive housing?

 

[Bt Doctur]

Re: Unidentified Drain Plug

That led to a flushing port in the water pump base. no longer being used to flush the motor.

 

[Bt Doctur]

Re: Unidentified Drain Plug

not letting me edit again so ,remove either one of the top plugs and just fill from the bottom untill it comes out a top plugt

 

[leegoldring]

Re: Unidentified Drain Plug

not letting me edit again so ,remove either one of the top plugs and just fill from the bottom untill it comes out a top plugt

Thank you for your response Bt Doctur. Regarding the drain hole, there a another flush hole on the opposite side, middle of the housing that leads directly into the water pump. This one is towards the front.

Perhaps this other hole is used to flush out the cavity that the shift shaft sits in?

 

[Fun Times]

Re: Unidentified Drain Plug

Thank you for your response Bt Doctur. Regarding the drain hole, there a another flush hole on the opposite side, middle of the housing that leads directly into the water pump. This one is towards the front.

Perhaps this other hole is used to flush out the cavity that the shift shaft sits in?

On most models that is a drain relief hole. In service manual #1 page 6A-4 looks to be called an air vent hole or oil vent screw from drive shaft housing for drives with interconnected oil chambers.

Step #1 says to drain the gear lube from the gear housing by removing the filler hole screw and vent screw or oil vent screw from drive shaft housing for drives with interconnected oil chambers.

The photo also shows the center flush hole mentioned by BT Doctur.

Edit: Are there two of them screws? one on each side? The info I posted of the vent hole don't seem right for the location described.

 

[leegoldring]

Re: Unidentified Drain Plug

Here is what I have on the total outdrive:

Drive Housing:
1. 2 Vent plugs- one on each side, opposite each other (one is shown in the diagram page you mentioned - there is an opposing one on the other side.

Gear Housing:
1. A Flush plug - as shown in the diagram
2. An Air Vent plug - as shown in the diagram, port side
3. The unidentified plug - on Stbd side, that leads directly into the lower shift shaft cavity

One thing that I noted was no hole in the top flange - supposedly a connecting chamber between the housings - perhaps the lack of the chamber hole has something to do with these plugs. Just not sure. Thanks for your further insight.

 

[Fun Times]

Re: Unidentified Drain Plug

Be sure to read page 1C-9 and 1A-13.

On page 1A-13, above step two say be sure the drain holes are open.

Now I have no experience with the 1C drive, but I'm starting to think that maybe someone has added that screw themselves because usually that area is open on later models.

Keep in mind that this is just a discussion about the screw so please don't just remove it. Maybe someone with an older 1C drive will see this and chime in. Good luck.

 

[leegoldring]

Re: Unidentified Drain Plug

Bt Doctur: regarding your response "...That led to a flushing port in the water pump base. no longer being used to flush the motor. "

Is there any advantage to using this flushing hole port as opposed to using flush muffs over the water intake grilles? I do see an image in the service manual for the "flush adaptor"; I assume I could create a similar adapter for a hose that connect to the 3/8-16 hole. Thank you in advance for your response.

 

[Bt Doctur]

Re: Unidentified Drain Plug

 

[leegoldring]

Re: Unidentified Drain Plug

Ah, thank you for the image Bt Doctur; it all makes sense now. Chambers are separate.