Induction leak

[Guest]

All the threads were clean, absolutely clean ,no corrosion. There was a slight sign of rust (iron oxide) in the hex drive of the plug. If there was corrosion I doubt it would have come out at all.

These cylinder assemblies have many steel /aluminum contact surfaces with no corrosion issues.

This plug is listed in the parts guide as 1/8 x27 x pipe thread. There are different tapers for pipe threads but pipe thread tends to wedge itself into the female thread for sealing and locking..

Normally Lycoming installed a helicoil in pipe threads in cylinder heads.

Clarence

[jetdriven]

Except in the IO-360 fuel injector nozzle holes. Then if the injector gets loose it vibrates in the hole and strips the hole. It's 1/4" NPT and Lycoming specifies 50 inch pounds btw.

Come to think of I i have never seen an NPT helicoil in a Lycoming engine

[Guest]

Current IPC shows the following:

STD1872- 1/8"-27 insert helicoil tapered

1102-plug 1/8-27 NPT, Allen

Both are used in the injector hole as well as the MAP/ primer jet hole.

Clarence

[jetdriven]

I wish they heli-coiled the injector holes in my cylinder heads. They were simply tapped and the threads were very poor quality. #1 and #3 were also tapped to the wrong depth, torquing the injector to 50 INLB they were upside down. Undertorquing them slightly they woud kinda line up, but they fretted in the holes and now those two are stripped.

[Guest]

Im sure you could buy the helicoil kit for less that the cost of replacing the 2 cylinders. $110 on Amazon.

Clarence

[N201MKTurbo]

My current IO-360 is the fourth one I've owned. None have had helicoils in the injector holes.

 

Mechanics have been fixing stripped cylinder holes with helicoils for ever. I would imagine in today's environment some may be hesitant to do any repairs unless they are explicitly authorized. By putting the helicoils on the parts list, it authorizes them to be added.

 

I wouldn't add them unless mine were stripped and I couldn't fix them with a pipe tap.