Helicoil Insert/Install – Intake Cover TD20

[John Gragg]

Pulling the intake side plate off my ’48 TD20 and the screw broke. Almost got it out without incident, but last minute it broke off. I was able to get it out, but missed the mark on dead center of the screw and ended up buggering up the threads on the hole.

I ordered a helicoil set for a 10-24 thread. I just got them and realized they don’t have any type of sealer on their outside threads (which will be screwed into the tapped hole I drill out with a 13/64 drill).

Check me on this since I’m not well versed on 2-strokes. Does the intake ever see pressure (as in compression)? I’m thinking it only ever has vacuum inside of it, correct? Regardless, should I install any type of thread sealant between the outer threads of the helicoil and the tapped threads of the workpiece to prevent vacuum or pressure leakes? If so, what would you all use? Ultra Black?

Thanks!

John Gragg
RIverside, CA

Just starting in the hobby, please be patient.

48 Sea King 5hp GG9014A
49 Sea King 5hp GG9014A
48 Johnson TD20
49 Johnson TD20
54 Johnson QD15
55 Johnson CD12

[frankr]

Having a bit of trouble visualizing the third port engine in my mind and don’t know which screw is broken. But chances are that it does have both pressure and vacuum. That would be true for any screws that enter the crankcase.

1 user thanked author for this post.

John Gragg

[crosbyman]

suggest you use solid heli coil inserts  not the spring type shown in your photo

the solid inserts  have  spikes at one  end and  you  set it (lock it)  in place with a hammer blow.    red loctite  would  secure it  and  use  blue  lock-tite on the bolt itself

see this oem kit with solid inserts  and  punch provided to secure the insert in place

 

 

jmho

 

 

Joining AOMCI has priviledges 🙂

1 user thanked author for this post.

John Gragg

[aquasonic]

The intake cover also handles exhaust on the “T” series Johnsons. The solid threaded inserts are good, but the ones I’ve seen are larger in diameter than the Helicoil insert. You may not have enough thickness at the mating surface on the motor side. The 10/24 Helicoil definitely works, but even that doesn’t have much extra room. I recall using 1 or 2 on a TD-20 intake/exhaust cover successfully. Use the exact size cobalt drill that the kit recommends.

For sealing/locking in the threads, red loktite works well. Make sure that the Helicoil threads are slightly below flush on the drilled hole so as not to interfere with the screw installation. Don’t over sink the Helicoil either. They are not designed to back out. Take your time, and check as you go. Once installed, don’t forget to break off the tang as per the instructions.

 

 

1 user thanked author for this post.

John Gragg

[John Gragg]

aquasonic wrote:

The intake cover also handles exhaust on the “T” series Johnsons. The solid threaded inserts are good, but the ones I’ve seen are larger in diameter than the Helicoil insert. You may not have enough thickness at the mating surface on the motor side. The 10/24 Helicoil definitely works, but even that doesn’t have much extra room. I recall using 1 or 2 on a TD-20 intake/exhaust cover successfully. Use the exact size cobalt drill that the kit recommends.

For sealing/locking in the threads, red loktite works well. Make sure that the Helicoil threads are slightly below flush on the drilled hole so as not to interfere with the screw installation. Don’t over sink the Helicoil either. They are not designed to back out. Take your time, and check as you go. Once installed, don’t forget to break off the tang as per the instructions.

 

 

Thank you. Yes, my first order was the EZ Lok type since, as Crosbyman stated, they are solid inserts. But as you commented, there is very little room on the thin wall where this insert/screw is going. I don’t remember what size drill and tap they included in the package, but it was large enough that there would be almost no metal left on the sides of the screw. Sent it back and ordered the Helicoil. The helicoil is much smaller and gives me room to drill/tap. The drill size is only 13/64, so I’m good.

I was thinking about it last night. Although I’ve never had the enjoyment of stripping out a spark plug hole, I know many who have. Helicoils work just fine in that application, so I’m sure I will be fine in this instance. And yes, I plan to use locktite red on the helicoil and blue locker on the screws like Crosbyman says.

Thanks for the reply.
Best Regards,

John Gragg
RIverside, CA

Just starting in the hobby, please be patient.

48 Sea King 5hp GG9014A
49 Sea King 5hp GG9014A
48 Johnson TD20
49 Johnson TD20
54 Johnson QD15
55 Johnson CD12

[Author]

Posts