Mercruiser 3.0 engine drain plug

[IanDal]

Hello all, this is my first time posting so pardon me if this topic has been covered before. I own a 99 Campion 525 with a Mercruiser 3.0 I/O. My first year owning I hired the wrong guy to winterize my boat. He broke off the blue plastic plug to drain the block. Don't worry he says I had a steel bolt that fits. It fits but it leaks about a quart an hour. It is also a 1/2 in. fine screw where the original brass fitting was 1/2 in. coarse. What do members think? Should I just get a coarse thread 1/2 in steel bolt and carefully try to rethread the brass fitting by screwing it into the hole? Or should I try to find a tap set that would match it. If so would a tapered tap be best? The blue replacement plug only needs about 4 threads for its depth.
Thanks for any help.

 

[Alpheus]

Re: Mercruiser 3.0 engine drain plug

Did he put the bolt into the block, or onto another fitting?

 

[IanDal]

Re: Mercruiser 3.0 engine drain plug

Did he put the bolt into the block, or onto another fitting?


Thanks for replying. There seems to be a brass fitting attached to the block that the blue plastic plug screws into. He screwed the bolt into the brass fitting which is where it leaks when I run it.

 

[Alpheus]

Re: Mercruiser 3.0 engine drain plug

Just get yourself another brass fitting and plastic plug.

http://www.mercruiserparts.com/Show...110&bdesc=Cylinder+Block,+Piston+and+Bearings

16,17,18

Or you can take out the brass fitting and go to Home Depot and get a brass plug that threads into the block...

 

[Bondo]

Re: Mercruiser 3.0 engine drain plug

There seems to be a brass fitting attached to the block that the blue plastic plug screws into. He screwed the bolt into the brass fitting which is where it leaks when I run it.

Ayuh,... Replace 'em Both... The Block is tapped 1/4" pipe thread...

 

[fat fanny]

Re: Mercruiser 3.0 engine drain plug

Bondo is right it should be 1/4 npt Just get a 1/4 npt pipe plug preferably brass and if you have to retap it only screw the tap in to a count of 7 threads on the tap and it will seat perfectly the seven threads isstandard on all pipe taps. Good luck

 

[IanDal]

Re: Mercruiser 3.0 engine drain plug

Thanks to Bond-O, Alpheus and Fat Fanny for their help.
Am ordering the new parts from Mercruiser today.

 

[RadioguyJ]

Re: Mercruiser 3.0 engine drain plug

If it was the blue plug that broke off inside the threaded part, why not just cut a notch in the plug with a knife and back the plug out with a screwdriver? That's how we fixed my boat years ago when that happened. In fact it just happened to me again on our 37 Formula last night. That's why I was on here searching for this topic. But last night our broke off down low at the oil cooler, so I think I am in trouble on this one.