Installing Helicoil questions for overtorqued sparkplug port

[tecke]

I wanted to make sure everything was set to factory specs on my '76 Johnson 35HP (I had the previous problem described on thread( http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=011753 )<br />,so I bought a new torque wrench and set about putting everything back together. I put the lower plug in fine, but the upper one lost it's resistance and the plug port now has no threads left- major bummer! <br /><br />I got a Helicoil kit and was going to install it. <br /><br />First I wanted to see if anyone could offer any advice or tips for when I do it. <br /><br />I was told by a friend to leave the head on and stuff a oily rag in to catch the debris, being careful to remove the oily rag with debris attached. I have good compression now, 120 PSI. They told me to leave the head on because I would not have to redo the head gasket and maybe mess it up -not me! I never break anything . <br /><br />Others have said to take off the head and get a new gasket- risking compression problems if I don't put the head back on correctly. <br />In reading some of the other posts on this board about stripped threads, I have seen references, but nothing that addresses all of my questions. <br /><br />One idea I saw was to fill the cyl with grease, then push it all out when done. What kind of grease should I use if I do this? I thought the grease would wreak havoc on the rings when the grease and oil don't mix and in turn burn the motor up. Someone else had said to use shaving cream to fill it then vacuum it out.<br />Any thoughts on either of those ideas, or does anybody have any other ideas?<br /><br />Anybody have pros or cons for either removing the head or leaving it on? Are head gaskets for this engine hard to come by? Can I make my own if I can't find one?<br /><br />Thanks for all your help! This is a great forum!

 

[Trent]

Re: Installing Helicoil questions for overtorqued sparkplug port

Vacuum it out.. Then oil it up and vacuum it again. Shaving cream is somthing Iv never heard of but sounds like a good idea??

 

[oldboat1]

Re: Installing Helicoil questions for overtorqued sparkplug port

Take the head off. Why risk it? Follow directions for installing the helicoil -- It's pretty effective. As an alternative, though, you might consider just getting another head. Depending on what your have in your area, it might be real easy to locate a head from a '76 parts motor -- or maybe consider just picking up the whole parts motor for future reference.

 

[P.V.]

Re: Installing Helicoil questions for overtorqued sparkplug port

Nah !!!! You don't HAVE to pull the head. Here's how I've done it many of times. Put the piston just beyond TDC, kind of on the down stroke but just ever so slight. Load up the oversize tap with grease, in the area inside the threads. As you start to cut new threads, remove the tap and remove the grease, which has captured the small pieces of aluminum. Don't cut too much at a time, as the grease/scrap may fall into the cylinder. It will take about 3,4 or 5 attempts to get all the threads done . I also go back after each removal and using a small scribe, look for any grease that has adhered to the hole . Now, if any does fall into the cylinder, just use compressed air to blow it out the spark plug hole. If you leave a small amount in the cylinder anyway, don't worry, it will probably go out the exhust port when you start it up. The worse thing that could happen is to get lodged in the electrode. BTW, check out the depth of the material on the cylinder head that the heli-coil will adhere to, Helicoils come in different sizes. You want one that is not too long. Better too short slightly than too long. Good luck !!!

 

[FlyBoyMark]

Re: Installing Helicoil questions for overtorqued sparkplug port

PV's got it rite...this is what we did to aircraft engines when the threads got stripped in the cylinders. Just a few turns at a time clean tap, grease again, clean tap again, regrease. Sticking an air chuck with a long skinny metal brake line inside the cylinder and blowing will help between turns. On aircraft engines we removed the other sparkplug for the dual ignition and blew air in that way constantly to blow any chips we missed out the way we were tapping in....

 

[oldboat1]

Re: Installing Helicoil questions for overtorqued sparkplug port

Well, I have to admit that I didn't remove the head on the one I did about a year ago (have only done a couple). I was concerned afterward, though, that the length of the insert was a little long (put it in too far), but the motor seemed to be OK -- also concerned that there might have been some filings, although I used a shopvac to try to draw out any debris. To do it again, I would remove the head. It's a simple matter -- easy to do, and also gives you a chance to clean up some carbon buildup on the crowns of the pistons and check out/clean the water passages (I'm usually fooling around with pretty old engines).

 

[tecke]

Re: Installing Helicoil questions for overtorqued sparkplug port

Well folks, I installed it last night. I did not remove the head and did as PV and Flyboy said with the grease (with some vacuuming also , Trent) and it went in like a charm. I'll let the thing cure until tomorrow then start it up. <br /><br />btw -oldboat1, thanks also for the replys, I took a good look inside and yes, there is a load of carbion in there, but that will have to be another job another season.<br /><br />Thanks again for all of your replys. I'll repost after I try to start it. tecke

 

[tecke]

Re: Installing Helicoil questions for overtorqued sparkplug port

The Helicoil worked like a charm. It runs great now.<br /><br />Thanks again for everyones help. tecke

 

[oldboat1]

Re: Installing Helicoil questions for overtorqued sparkplug port

hey -- good job, Tecke. Thanks for reporting back (nice to see success stories).