Manifold drain plugs leaking...

[avpaulb]

Hey All...

Just got the boat started after the winter's nap. Everything fine, except: two of the water drain plugs on the exhaust manifold are leaking. And yes they are closed.

Do these things go bad? Had the boat winterized, etc. Plugs appear to be a "butterfly-style" screw which screws into a threaded nut. Can't really tell if they are brass or steel.

Thoughts? Any links to replacement product?

Oh yeah: 1976, 3.0L Merc

 

[alldodge]

Re: Manifold drain plugs leaking...

Hey All...

Just got the boat started after the winter's nap. Everything fine, except: two of the water drain plugs on the exhaust manifold are leaking. And yes they are closed.

Do these things go bad? Had the boat winterized, etc. Plugs appear to be a "butterfly-style" screw which screws into a threaded nut. Can't really tell if they are brass or steel.

Thoughts? Any links to replacement product?

Oh yeah: 1976, 3.0L Merc

Sure could use a serial number because the butter fly drains do not add up on the manifolds. Either way your looking for (I'm guessing) 1/4 inch pipe plug drain cocks.

http://www.summitracing.com/parts/sdk-8a-8115?seid=srese1&gclid=CPvrm_q8k74CFYdFMgod4TwAqw

 

[achris]

Re: Manifold drain plugs leaking...

Pull those horrible things out and toss them! Replace them with a straight brass plug... The thread is a 1/8"-27tpi, which is a 1/8" NPT...

Chris.....

 

[avpaulb]

Re: Manifold drain plugs leaking...

Pull those horrible things out and toss them! Replace them with a straight brass plug... The thread is a 1/8"-27tpi, which is a 1/8" NPT...

Chris.....

I'll check those out, thanks.

Just saw your location Chris... one of the former members of Men at Work lives about 20 miles from me!

 

[avpaulb]

Re: Manifold drain plugs leaking...

OK, so ordered new plugs as suggested. Got the wrong ones, naturally.

As it turns out, the source of my issue was some gunk buildup inside of the plugs causing them not to close. I pulled them and cleaned and they are now closed. However,...

One of my old plugs is about 1/2 stripped! :mad-new: I can't get the darn thing to go back in! Any suggestions from the gallery for a quick and suitable replacement? The plug itself is actually 3/8" at the threads.

I'm going to try Fastenal to see if they have anything, otherwise I'm thinking checking the hardware store for a suitable bolt and rubber gasket just to plug the hole for now...

 

[Bt Doctur]

Re: Manifold drain plugs leaking...

that's called 1/4 inch pipe plug, Remove the adaptor for the winged unit and replace with a solid plug.

 

[fishrdan]

Re: Manifold drain plugs leaking...

Remove the petcock fitting so you can match it up. A "good" auto parts store will have replacement petcocks, or your local hardware store will have brass pipe plugs if you go that route.

FWIW, I've had to replace the petcocks on my engine a couple of times over the years from them getting gunked up with debris. Now, when I'm draining the block/manifold, I rock them back-forth to flush out the grit while the water is draining. For me, I wouldn't want to use plugs as I drain the engine many times during the winter, after each use, would be a pain fiddling with plugs in the freezin cold.

 

[avpaulb]

Re: Manifold drain plugs leaking...

that's called 1/4 inch pipe plug, Remove the adaptor for the winged unit and replace with a solid plug.

The problem plug in question does not have an adapter to speak of. The plug screws directly into the exhaust manifold, with the "butterfly" screwed into it. The only drain that has an adapter is on the lower part of the block itself.

I may post a picture tomorrow.

 

[fishrdan]

Re: Manifold drain plugs leaking...

Petcock...

 

[Volphin]

Re: Manifold drain plugs leaking...

You can get longer plugs. Check at your local plumbing supply store. The big boxes won't carry that though...

 

[Bt Doctur]

Re: Manifold drain plugs leaking...

get rid of those radiator drains , use a solid plug or the marine "winged drains" or the "plug drain"
http://www.bing.com/search?q=block ...F0B6A3DC45AE96F&form=CONBDF&conlogo=CT3210127

 

[alldodge]

Re: Manifold drain plugs leaking...

Go find a 1/4 NPT tap and clean out the threads. Then put in a new 1/4 NPT plug as BT Doc mentioned

 

[avpaulb]

Re: Manifold drain plugs leaking...

Go find a 1/4 NPT tap and clean out the threads. Then put in a new 1/4 NPT plug as BT Doc mentioned

Like so?...

1/4"-18 HSS 4 Flute NPT, Taper Pipe Tap | Fastenal

 

[Bt Doctur]

Re: Manifold drain plugs leaking...

yes, that one. but do not run the tap in all the way. thoses threads are tapered. run it in just enough to clean the threads

 

[avpaulb]

Re: Manifold drain plugs leaking...

Boat mech hooked me up with just a plug. No petcocks. Makes a bit more sense!

 

[seilings]

Re: Manifold drain plugs leaking...

Is it a blue plug? that must be the O-ring problem. Just get another bigger edge but same size O-ring.


I had the same issue before, one of my manifold plug is leaking water, and couldn't be seen ( small amount water down alone the engine mount support). So every time I came back from a trip, even only one or two hours, I can see some water in bilge.
Took me a while try to figure out where does the water came from until I notice the difference of the condition of the two engine mounts.
The starboard engine mount looks like more rusted than the other side.

 

[fishrdan]

Re: Manifold drain plugs leaking...

get rid of those radiator drains , use a solid plug or the marine "winged drains" or the "plug drain"
block and manifold drain plugs - Bing

Thanks BT DR. I haven't seen those type of drains before. They look a LOT better then the automotive/plumbing petcocks.