Broken water drain on manifold

[Lift12]

I've had the misfortune of breaking off the brass drain **** on one of my manifolds during winterizing. 1989 5.7 Alpha 1. I see that the brass fitting has been discontinued in favor of a plastic drain by Mercury. The brass version is still readily available.
Is there an advantage to one over the other? My instinct is that a metal part is superior to a plastic part but am I mistaken?

 

[Scott Danforth]

go to your hardware store and buy a brass pipe plug. the drain cocks are nothing special, they are brass radiator cocks, available anywhere.

Plastic has no reason to be on an engine other than to make the OEM more money (because its cheaper, not better)

 

[tank1949]

1/2" common thread on ss 1/2-3/4" long bolt with skinny o ring will work in a pinch. I use Teflon tape too. Plastic sucks and will get brittle in a hot engine compartment.

 

[Lift12]

Thank you!

 

[Bondo]

1/2" common thread on ss 1/2-3/4" long bolt with skinny o ring will work in a pinch. I use Teflon tape too. Plastic sucks and will get brittle in a hot engine compartment.

Ayuh,..... That would replace the blue plastic wing-plug,......

Lift12 says it's a brass drain, so it'll be 1/4", or 1/8" pipe threads into the manifold,......

 

[tank1949]

Ayuh,..... That would replace the blue plastic wing-plug,......

Lift12 says it's a brass drain, so it'll be 1/4", or 1/8" pipe threads into the manifold,......

Hum... Mine, that I just replaced, were all 1/2" blue plastic POS(s). I tried MNPT, but threads didn't match at all. 1/2" SAE (common) worked fine, at least for me.

 

[Scott Danforth]

Hum... Mine, that I just replaced, were all 1/2" blue plastic POS(s). I tried MNPT, but threads didn't match at all. 1/2" SAE (common) worked fine, at least for me.

correct, the blue plastic POS's are 1/2-13, however back in 1989, they didnt bolt in adapters and other hypercomplexification. they used 1/4 NPT pipe plugs or brass radiator cocks.

if you want to replace the blue POS's with stainless https://www.hardin-marine.com/p-810...-plugs-mercruiser-22-806608a02-8m2000874.aspx

 

[tank1949]

correct, the blue plastic POS's are 1/2-13, however back in 1989, they didnt bolt in adapters and other hypercomplexification. they used 1/4 NPT pipe plugs or brass radiator cocks.

if you want to replace the blue POS's with stainless https://www.hardin-marine.com/p-810...-plugs-mercruiser-22-806608a02-8m2000874.aspx

My MC exhausts manifolds would not take pipe thread. I tried. However, my manifolds, although MC, are like new and perhaps MC (not Barrs) changed thread designs? I would have preferred pipe thread. They seem safer and easier to seal.

 

[Scott Danforth]

the later MC manifolds have the 1/2-13 threads, however a 1989 manifold would have had a brass 1/4npt male to a 1/4npt female coupler with the 1/4npt brass ****.

yes, MC changed their manifolds when they started using the plastic blue wonders.

 

[Lou C]

Could never understand why they did that (plastic drain plugs) except for cost reduction. You can have the same metal plugs that my engine has had in it for 32 years! And corrosion, well if you coat the threads with gasket sealer they never corrode in place even after approx 20 years of raw water cooling in salt water!
Another half baked Merc idea like the single point drain with the plastic housing.

 

[Scott Danforth]

Could never understand why they did that (plastic drain plugs) except for cost reduction. You can have the same metal plugs that my engine has had in it for 32 years! And corrosion, well if you coat the threads with gasket sealer they never corrode in place even after approx 20 years of raw water cooling in salt water!
Another half baked Merc idea like the single point drain with the plastic housing.

dont even give them the credit of "half-baked"

 

[Lift12]

... a 1989 manifold would have had a brass 1/4npt male to a 1/4npt female coupler with the 1/4npt brass ****.

This is precisely what I have. Thanks for your help.

 

[tank1949]

This is precisely what I have. Thanks for your help.

Easy out and elbow grease and go back with MNPT!

 

[crazy charlie]

Any time i change out my manifolds I save the brass and reuse it and put the blue plastic where it belongs.....in the drawer.Charlie