block drain plug stripped
 

I was de-winterizing the boat last night and when putting in the starter side block brass drain plug it (the plug) stripped out. It was getting late and dark so I just stopped there. I felt around as best I could and I think they might be damaged a little, but given the location it was impossible to see w/o a mirror which I didn't have along with me. The engine is a 1989 454 330hp Mark IV.

My current plan is to 1) run a tap into the block to clean up the threads, 2) go back into the block with a m-f adapter and bond that into the block, 3) add a cap to the end of that so future seasons I leave the block/adapter joint alone.

Thoughts, advice, comments?

The block threads shouldn't be damaged from the brass plug.

Altough you might wanna clean the threads with a tap before putting in a new plug.

I'm just wondering how a brass plug stripped the threads on an iron block. Are the threads missing on the plug? If so, they're probably still in the threads in the block- I'd try removing them with a pick first. A tap migh catch the wrong way and then you's have two sets of concentric threads in the block- a bigger mess.

You might want to get a closer look before you do anything.

I'm sorry, I wasn't clear. The brass plug threads are stripped. I don't know the condition of the block threads.

How about a round wire bush to clean up the threads first? Given it's location it's going to be tough to get a pick on the threads, but I'll give it a try.

ECeptor.. the iron block is pretty tough. It may have the brass threads wedged in. One thing you may try is a thread restorer. Sort of like a tap but without the sharp cutting teeth. A wire brush may just dislodge them, but as Chris said, the pic would be better.. Just have to stand on your head to see what you're doing.. :) Mirrors and flashlight can help also.

Good luck with it..

I think you guys are right. I should get a good light, good mirror, good pick or two and be in a very patient mood then get in there and manually clean out those threads. Then run a restorer or tap in after that to make sure everything is nice and clean.

My take away is new brass plugs every few (3?) seasons. I suspect the one that failed is the original.

As tight as it is down there, you just don't want to risk cross-threading a tap in there and turning this into an engine removal/disassembly deal. Pull the exhaust if you have to and do it right.

On block drains, I use a NPT to JIC (37 degree flare) and a cap. They're steel and tough. use a hardening sealant on the block side so it doesn't come out when you pop the cap. Order a couple extra caps for when you drop one in the bilge.

Good advice all-around - thanks guys!

A digital camera with Macro mode is good way to find out what you're dealing with. I agree that the block is probably fine. Remember that you're dealing with tapered threads - run a tap in too deep, and the plug or fitting might not ever tighten up.....

Man, I hate pipe threads.

Block Drains
 

Got the answer <--------- Right Here. Just fill the hole with JB Weld. Every Fall just drill it out with your Dewalt Cordless. Come Spring, Re-apply JB Weld.

Problem Solved :cool-smiley-011:

:cool-smiley-027: See..??? Rat Motors do live out there:hitfan:

Eceptor,
Merc makes a drain plug that is brass and has a plastic plug. I bought a few extra plugs for that fitting. Works out pretty good. You can remove it with your fingers, has an oring.
Dick

I used to have the same problem every year with the riser drains in my old stinger 230. Water and silt would collect in the threads and rust them up enough where the plugs wouldnt go in no matter what. The threads in the castings were never a problem. A cleanup with a chaser or tap works fine. Just start it carefully by hand and make sure yoiuve grabbed some threads before putting any forece on them. Also next winter, brush some waterproof bearing lube on the threads. Never had a problem after.

who drops things in the bilge? :cool-smiley-011:

Good advice everyone. I'm going to look into that Merc brass/plastic plug that can be manipulated by hand.

Bad news is I won't be able to get to it for a few weeks. I managed to dislocated my shoulder Sunday while roller blading, so no bilge gymnastics for me for a while....:( No way I can get to that plug without raising my arm in a direction it (or me or my Dr.) doesn't want to go right now.

OTOH, I might be able to pull off the JB weld idea...but would have to get a right-angle drill next fall...:cool-smiley-011:

Otherwise, if you can't get back in there to drill the JB weld out later, you can always leave a straw from Burger King in the middle and just plug it off with a bread twistee. Then in the fall you can just take the twistee off to drain the block.

Even better.

:cool-smiley-027:
Yup, or gum in case there isn't a twisty handy...always got gum:cool-smiley-011: