Drain plugs striping out

[Rupp]

Guys,
I de-winterized my Volvo Penta 5.0 GL PEFS and the block drain plugs hardly screw in any longer and they are nearly stripped. What can I do to get these plugs to go into the block at least a "round or two". One of them today is probably not one turn into the block and I'm afraid to turn it any further. Thanks in advance for any information.

 

[alldodge]

Sounds like they have been tightened way to much. If you look at the threads both the block and the plug, are they both stripped out?

Can post a pic of the plug?

 

[Rupp]

No the drain plugs are soft brass which I'm guessing was designed to prevent from stripping out the block threads. It seems the block threads are very corroded but these drain plugs never "screwed in" more than a turn to turn and a half. I can't take pictures at the moment as I keep my boat at the lake and hour and a half away.

 

[alldodge]

If the block is also stripped, may need to get a 1/4 NPT-M to 1/4 NPT-M or one of the Merc Blue bushings. I would clean it up real good, put a slight bit of JB Weld on the threads, then screw in place. Then add more JB to the outside of the block and the fitting. Once dry, use another plug to close or Blue plastic thumb screw depending on which option you go with.

 

[Rupp]

The block doesn't appear (what little I could tell as they are way under the engine and covered with other pipes on one side) to be stripped. These are the plugs that screw into my block.

https://www.iboats.com/shop/pub/med...0ab036de70892d86c6d221abfe/5/9/IB00059775.jpg

 

[Scott Danforth]

Pick up a 1/4 npt pipe tap, grind the point off (it will hit the cylinder liner) and chase the threads

 

[fishrdan]

Agree with AD and Scott, pick up a tap and slowly/carefully clean up the block threads. And get some new plugs.

Same issue with my block, brass plugs rounded off and difficult to install. Cleaned up the block threads, and new plugs threaded in like butter.

 

[Lou C]

Are you sure that is what you have? On my engine there is a cylinder shaped fitting that screws into the block and then the drain plug (brass) screws into that. The plug has a t at the end of it not a hex. Never had any problem with these.

 

[Scott Danforth]

Lou,

not all motors have a nipple installed like you do. many have the brass plug going directly into the block. the problem is the threads rust over winter. normally 1/4 turn with a pipe tap is all that is needed to clean out the threads.

 

[alldodge]

I would suggest using a bottom tap, there will be no point

 

[Rupp]

Thanks for all the info guys I really do appreciate it. I'm not a mechanic so do any of you have a 1/4 npt pipe tap that you'd recommend. I looked on Amazon and there are dozens.

 

[Lou C]

would a thread chaser be better than a tap in this case?
one thing that helps is to coat the threads with Permatex Aviation sealer or similar which will cut down on corrosion.

 

[BRICH1260]

You might just first try to clean the threads up by putting a gun bore bronze brush in a drill and spinning in in the hole.

 

[alldodge]

Do agree you could just use a wire brush to clean the threads, like a plumbers brush. Could get either one at Home Depot, Lowes, local hardware store. Can also get the 1/4 NPT plug there

 

[Bt Doctur]

This happens quite often when the plugs are left out of a cast iron block, they rust up. !/4 inch pipe tap and be very careful on how deep you go. Pipe threads are tapered. Get rid of the brass plugs and install brass fitting with the brass wingd plug or the blue plastic one

 

[Bt Doctur]

 

[Rupp]

This happens quite often when the plugs are left out of a cast iron block, they rust up. !/4 inch pipe tap and be very careful on how deep you go. Pipe threads are tapered. Get rid of the brass plugs and install brass fitting with the brass wingd plug or the blue plastic one

Do you have a link to such a device?

 

[Bt Doctur]

 

[Bt Doctur]

Do you have a link to such a device?

It`s just a standard 1/4 pipe tap

 

[Bondo]

Do you have a link to such a device?

Ayuh,.... Google it,....