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: