stripped flush port

[shadowrider]

I went to put the flush plug back in and it just kept spinning. Appears that the hole is stripped, not the plug. Any ideas on how to fix ? Too shallow for helicoil in my opinion. Welding not a great option, penetration would be a problem.

 

[79Merc80]

Re: stripped flush port

Hello:

What engine are we talking about?

 

[shadowrider]

Re: stripped flush port

The engine is a Mark 58.

 

[MercMan82]

Re: stripped flush port

I believe the thread is the same for all. 5/8-11 is what it was. Take the waterpump base completely out. You can drill it 21/32, and tap next size up, 3/4-10. Buy a set screw same thread size and you may have to grind the nose of it for clearance sake to make sure it fits the counterbore of the waterpump where it seals. Cheaper than a welder and not too hard to do. Just make sure you tap it as straight as possible.

 

[shadowrider]

Re: stripped flush port

To get the pump base out I would have to remove the driveshaft no ? I dont have a pump removal tool.

 

[MercMan82]

Re: stripped flush port

What year?

 

[shadowrider]

Re: stripped flush port

1958 is the year.

 

[merc850]

Re: stripped flush port

On my Mark 58 the flush plug covers a hole in the water tube outlet and is not part of the waterpump assembly, like MercMan 82 says tap it larger. If you have the flushing attachment it will have to be re-threaded to fit.

 

[shadowrider]

Re: stripped flush port

You are correct I was not looking at it close enough. I am thinking about welding it up or I just might tap it to 5/8-18, as the hole is probably just right for that thread. Thanks for your input.

 

[shadowrider]

Re: stripped flush port

Well, I did it again. I did not measure the plug before posting my 5/8-18 idea. The plug is 3/8-16, just to clear up what I am talking about. In this case, 3/8-24 fine may work.

 

[MercMan82]

Re: stripped flush port

3/8-24 drill size is only .016 bigger than 3/8-16 which is .312. 7/16-14 would be the one you want to go with. If you stripped 3/8-16 it will be .375 or a little bigger. Drill size for 7/16-14 is U (.368) so you don't need to drill it, just tap it.