Brass block drain plug leaking like a sieve

[Rupp]

Guys,
This year I purchased new brass block drain plugs and I used a thread cleaning chaser to clean our the existing holes. The chaser was easy to use and I didn't even have to use a wrench to screw it in and out so the threads were mostly clean. I put in the new brass plug, tightened it down and no matter what I do it leaks and leaks bad. Should I use plumbers tape to try to eliminate the leak?

 

[ESGWheel]

Two concerns jump out to me regarding your description: that it leaks bad (regardless of how much its tightened) and that the thread chaser did not even require a wrench. This translates in my mind as possible stripped threads. Do you still have the old ones? Inspect their threads to see if there is something filling the valleys of the threads > this would be the stripped threads from the block. Can you post pictures of the old ones and how bad the new ones are leaking?

 

[cyclops222]

If you use TEFLON TAPE ? It should only be applied on the pipe threads in the correct direction.
Or you can apply Plumbers Pipe Dope. The dope is only brushed onto the MALE threads. That way as you screw in the fitting. Any excess is squeezed out of the connection.......If you put pipe dope into the female threads ? ALL the excess dope is pushed way into the engine. Not good.

 

[alldodge]

Guys,
This year I purchased new brass block drain plugs and I used a thread cleaning chaser to clean our the existing holes. The chaser was easy to use and I didn't even have to use a wrench to screw it in and out so the threads were mostly clean. I put in the new brass plug, tightened it down and no matter what I do it leaks and leaks bad. Should I use plumbers tape to try to eliminate the leak?

Like ESG there is something wrong in what you have tried
The block drain is a NPT (national pipe thread) which means it is tapered thread, not straight. While thread sealant is very helpful, it's not absolutely needed with a cast iron block and brass plug

What tap did you use and what plug?

 

[cyclops222]

Pipe fitting threads could be SAE American straight or( tapered ) or even metric. Happens

 

[Horigan]

I would replace the whole drain plug and move on.

 

[Chris1956]

Std Garboard drain plugs are tapered. You would need a special NPT tap to clean the threads, vs a std bolt tap. The Garboard drain plugs do not normally leak, even when put on dry.

If you have the correct plug for the garboard drain, and it leaks, you need to check the garboard drain fitting itself. Maybe it is leaking around the fitting? Check for rot in the transom.

 

[ESGWheel]

I would replace the whole drain plug and move on.

The OPs issue is the block drain plugs, they should look like this.

Guys,
This year I purchased new brass block drain plugs and I used a thread cleaning chaser to clean our the existing holes.

I have been looking for NPT (tapered) thread chasers before and have not found them. I do have both taps and thread chasers for both inch and metric standard threads, but only taps for NPT. What is the brand / source for the NPT chasers? Thx

 

[alldodge]

NPT does not have chasers
To clean threads the tap just goes in and back out. Once it makes contact with all threads, the more it's turned the larger the hole is made. No issue with going a tad larger, just don't do more then maybe a 1/4 turn or so

 

[ESGWheel]

NPT does not have chasers

That would explain why i cannot find them

Guys,
This year I purchased new brass block drain plugs and I used a thread cleaning chaser to clean our the existing holes.

Rupp: i am back to there is a larger issue then a simple leaking replacement. Can you now also post pics of the thread chaser you used?

And note the pic i posted of the block drain. Do your new ones look like that? And to double confrim, its leaking between the adaptor and the block (vs the adaptor and the plug). Correct?

Something is not right, but i know it can be fixed and folks here are willing to help.

 

[Bondo]

Ayuh,..... This is what I use,......

 

[Lou C]

I have those adapter pieces in my block and my rule is if they don’t leak DONT touch em! I replaced the original t handle drain plugs with Merc hex head brass plugs to make it easier to remove.

 

[Chris1956]

Sorry, block drains and plugs are a bit different. Maybe replace both adaptors and plugs.

From Flea-Bay: TWO PACK Mercruiser Exhaust Manifold & Engine Block Drain Plug KIT 22-16951Q1

 

[Donald0039]

I am thinking there is an issue between SAE thread and NPT thread. You can use Teflon tape on NPT threads. The adaptor mentioned is good but it reduces the diameter and chunks of rust can jamb the adaptor. So when draining the block one needs to stick a long nail all the way through the adapter to dislodge any chunks of rust.

 

[flashback]

I installed ball valves on mine but you still need to rod them when draining.