Merc 5.0 MPI drain plug

[wineguy10]

I identified a leak when I started up the boat for the season. I had a mechanic do my oil change, fluids and start up and he said I was good to go.

Can anyone confirm if this leak is coming from a broken drain plug based on the attached pictures? If not, other ideas? Note, yes, I did call my mechanic and he is backed up so I'm trying to at least understand the issue.

I have a Merc 5.0 MPI engine from 2006. Thank you

 

[dubs283]

Is a broken drain plug

Your mechanic should have one on hand, if not you can get one easily online

 

[Scott06]

As mentioned broken plug. They need to be replaced every couple years…

you can probably get it out by heating a screw driver with a torch when hot melt it into plug to get a grip

 

[QBhoy]

Hi. These are quite commonly known now for not seating very well. If you close them clockwise anything close to weakling level hand tight…they will not seat and keep turning. You will likely find that if you back the valve off a few turns (water will drain out…don’t worry about it)…then slowly start to close her clockwise gently…at some point you will feel a tiny bit of resistance…stop there and see if it’s still looking. You can feel the valve seat if you are gentle enough.
Others have said it could be a leaking quick connect plug in the network…but even if that was the case…it shouldn’t leak from there if that valve is seating closed properly. Have a go at what I’ve said there and let us know. I have exactly the same with mine. It’s not like a tap (faucet) in the kitchen. Requires real delicacy.

 

[wineguy10]

Is a broken drain plug

Your mechanic should have one on hand, if not you can get one easily online

Thanks for confirming. The mechanic is backed up so plan to attempt to fix myself. The difficulty looks to be getting to it.

 

[Scott Danforth]

I would get the stainless plugs from Hardin/ CP

 

[wineguy10]

As mentioned broken plug. They need to be replaced every couple years…

you can probably get it out by heating a screw driver with a torch when hot melt it into plug to get a grip

Thanks for confirming. A friend recommended using an easy out tool to get the cracked piece out. I may start with that and try your tip if that doesn't work. Will let you know.

 

[Fun Times]

See item number 2 which is the blue plug in question, https://www.mercruiserparts.com/bam/subassembly/31850/11652/250

PLUG KIT, (.500-13) Royal Blue 8M0119211

 

[QBhoy]

Thanks for confirming. A friend recommended using an easy out tool to get the cracked piece out. I may start with that and try your tip if that doesn't work. Will let you know.

Hold on. I’m co fused a little. So I thought you meant it was leaking from the outlet hose it’s meant to come out when the valve is opened. So the blue plug there has ruptured ? Or is it not a quick drain with the extended vertical valve handle ? Either way, my co cern might be why it’s burst. Did it freeze with water still in the block and manifolds ?

 

[dubs283]

my co cern might be why it’s burst.

It's not uncommon for the plug to shear like the one pictured. Happens due to age, not freeze damage

OP gets a new plug, installs it and goes boating. Summer full of fun boating memories

 

[wineguy10]

Hi. These are quite commonly known now for not seating very well. If you close them clockwise anything close to weakling level hand tight…they will not seat and keep turning. You will likely find that if you back the valve off a few turns (water will drain out…don’t worry about it)…then slowly start to close her clockwise gently…at some point you will feel a tiny bit of resistance…stop there and see if it’s still looking. You can feel the valve seat if you are gentle enough.
Others have said it could be a leaking quick connect plug in the network…but even if that was the case…it shouldn’t leak from there if that valve is seating closed properly. Have a go at what I’ve said there and let us know. I have exactly the same with mine. It’s not like a tap (faucet) in the kitchen. Requires real delicacy.

Thanks. Appreciate the tip.

 

[wineguy10]

Hold on. I’m co fused a little. So I thought you meant it was leaking from the outlet hose it’s meant to come out when the valve is opened. So the blue plug there has ruptured ? Or is it not a quick drain with the extended vertical valve handle ? Either way, my co cern might be why it’s burst. Did it freeze with water still in the block and manifolds ?

It did not freeze since I store the boat in a heated warehouse. I can only assume the the knob on the drain plug broke off from over tightening. I'm thinking the plugs are original from 2006. Not sure, but making an assumption. Does that make sense?

 

[wineguy10]

See item number 2 which is the blue plug in question, https://www.mercruiserparts.com/bam/subassembly/31850/11652/250

PLUG KIT, (.500-13) Royal Blue 8M0119211 View attachment 381194

This is great. I just ordered off Amazon. Also ordered an easy out tool to help get the cracked one out. Interesting part will be getting access to get the old one out.

 

[wineguy10]

It's not uncommon for the plug to shear like the one pictured. Happens due to age, not freeze damage

OP gets a new plug, installs it and goes boating. Summer full of fun boating memories

Thanks

 

[Scott Danforth]

I can only assume the the knob on the drain plug broke off from over tightening.

Nope, just crap plastic that is prematurely aged by engine heat

That's why I recommend the aftermarket stainless ones, or a 3/4" long 1/2-13 bolt with a washer and O-ring in a pinch

 

[wineguy10]

Nope, just crap plastic that is prematurely aged by engine heat

That's why I recommend the aftermarket stainless ones, or a 3/4" long 1/2-13 bolt with a washer and O-ring in a pinch

I'm going to ask my mechanic to look into. Thanks for the recommendation.

 

[QBhoy]

It's not uncommon for the plug to shear like the one pictured. Happens due to age, not freeze damage

OP gets a new plug, installs it and goes boating. Summer full of fun boating memories

Ah. Was just trying to think of a reason for it to be disturbed or opened, if it’s on the bulb manifold for the actual drain outlet…that’s if it had the extended handle like mine. Maybe it’s different from mine. That orange hose there is what I have on the bottom of the bulb. When I open the extended blue handle, it drains out there (then I take all the quick connect fittings off after…to make sure)