HELP! Brass threaded plug 2001 Mercruiser 4.3l

[bulletfever159]

I was replacing the oil pressure sensor, When I started the boat I noticed some gunk coming from the Starboard side near the starter. I found a small threaded bolt and saw the hole the motor was leaking this gunk. It is near the blue drain plug. I will attach a video but it isn't the best video. I found that water and oil is mixing (another issue I am trying to resolve whether it be a cracked block, head gasket, or manifold.) I can not find any mention of this threaded plug anywhere. I didn't feel any threads so I'm assuming I'll need to tap it and put a new bolt in. Any ideas? Is it possible to save the motor?

 

[bulletfever159]

The boat is in central Florida so I have never Winterized it.

 

[dubs283]

the video does not focus on where the sludge is coming from but based on the photo, it appears the bolt you refer to is plugging the dipstick tube hole in the block

in any case, the milky sludge oil in the video indicates most likely a cracked block. however, there may some other cause for the oil water mixture

 

[bulletfever159]

the video does not focus on where the sludge is coming from but based on the photo, it appears the bolt you refer to is plugging the dipstick tube hole in the block

in any case, the milky sludge oil in the video indicates most likely a cracked block. however, there may some other cause for the oil water mixture

This is on the starboard side, the dip stick insert is on the port side. I know i need to get a better photo but its top left to the blue twist drain plug. I am hoping the manifold is leaking and thats the issue.

 

[nola mike]

Looks like the block drain to me

Edit: because that is the block drain. Agreed, the thing next to it is the dipstick port

 

[bulletfever159]

I believe it’s this bolt, I just can’t find a part number or name.

 

[bulletfever159]

the video does not focus on where the sludge is coming from but based on the photo, it appears the bolt you refer to is plugging the dipstick tube hole in the block

in any case, the milky sludge oil in the video indicates most likely a cracked block. however, there may some other cause for the oil water mixture

I apologize, I re read this and I believe you are correct on this. The dipstick insert is on the port side but I believe they have the same hole on both sides

 

[Bondo]

The boat is in central Florida so I have never Winterized it.

Ayuh,..... Welcome Aboard,..... Pressurize the block's coolin' passages to find where the block is cracked,.....

 

[bulletfever159]

Ayuh,..... Welcome Aboard,..... Pressurize the block's coolin' passages to find where the block is cracked,.....

Thank you, I think I’m gonna try this and check compression. Really hoping it’s the manifold.

 

[bulletfever159]

Updated photos of bolt location, and possible site of leak?

 

[bulletfever159]

And here are what the manifolds look like, thoughts?

 

[jesse_boston]

Manifolds look like they were okay until a bunch of oil started getting pushed out through 'em.
Is the green paper gaskets? Not my fave... but wouldn't cause this.

Is the plug between the exhaust passages where the goo is shooting out?

Regardless at this point you're looking at major engine repair... Last I checked, oil doesn't go into any of the manifolds, so the water and oil are mixing in a cracked block, a cracked head, or a blown head gasket.

 

[bulletfever159]

Manifolds look like they were okay until a bunch of oil started getting pushed out through 'em.
Is the green paper gaskets? Not my fave... but wouldn't cause this.

Is the plug between the exhaust passages where the goo is shooting out?

Regardless at this point you're looking at major engine repair... Last I checked, oil doesn't go into any of the manifolds, so the water and oil are mixing in a cracked block, a cracked head, or a blown head gasket.

Yes, the silver bolt

Edit: Also if that's the case, why does the other manifold not look nearly as bad? when i took out the drain plug the water did not look milky, it was until that bolt blew off that I noticed the sludge, I pumped the oil out from the dipstick (the dipstick actually didn't indicate any milky oil, it looked like healthy oil) the oil I pumped out was mostly water. I am waiting on some stuff tools to come from Amazon so I can do all the tests, and waiting for it to stop storming.

 

[bulletfever159]

Fingers crossed a head gasket and its salvageable

 

[Rick Stephens]

Unlikely a head gasket fills your motor with water. Rain and an open engine cover, a cracked block, cracked head or rotted intake.

 

[bulletfever159]

Unlikely a head gasket fills your motor with water. Rain and an open engine cover, a cracked block, cracked head or rotted intake.

Yeah, I am kind of just guessing right now until I am able to do some tests. I am just confused as here in Florida we don't really get cold enough to freeze, the boat was getting warm on the port side riser when I parked it last August but it never got above 180 degrees. I am not sure what would have caused it.

 

[Rick Stephens]

Salt water boat? Could just be a rotted through intake or head from the salt corrosion.

 

[bulletfever159]

Salt water boat? Could just be a rotted through intake or head from the salt corrosion.

Oh good idea! Yes it is a salt water boat. And before I got it, it sat for at least two years.