Kohler spark plug /head threads

[Dave Sherburne NY]

I have a few Kohler engines and at least 2 of them the spark plug threads are stripped out and replaced with Helicoil. I've never had good luck with the helicoil, it seems to stay with the plug when you take it out. Since the plugs are 14 MM do you think it would be possible to drill and tap the head to 18 MM ???? If so what 18 MM plug would be equivalent to the RH10???

 

[Bob]

I wonder if a TimeSert would fit in the threads made for the HeliCoil?
TimeSert

 

[Ken-Pa]

Boy , the kits sure are expensive if you only need to repair one hole . Unless it's your line of business . God bless

 

[Pete_5959]

I would try a NGK 2910. Reach is a little less but should fill the bill. It is a 18MM.

 

[MNGB]

If a helicoil is coming out with the plug it is not properly installed, in 45 years as an aircraft mechanic I've never had a helicoil come out on its own I have pried them loose and removed them. Even in cast iron they stay, who ever is installing them is using the wrong size depth wise.
Are you sure the is enough material to go to a 18 MM hole I'm thinking it will be very thin when your thur drilling and tapping.
GB in MN

 

[El Toro]

Just snug your sparkplugs. You don't need to torque them down tight. I would have a Keensert
installed & use the original plug. Hal

 

[Anonymous-0]

Try NAPA they have spark plug inserts by the piece or in a kit.They work great.

 

[Ronnie Graves]

I make my own insert , at a good hardware store look for a stainless steel adapter you will need 3/8x1/2 its gonna be NPT tap the head for the 1/2 pipe taper and run it all the way down (head should be off ) make sure the hex seats down good then take it back out and put Loctite Lock weld on it and put it back in the head , thread inside with a 14 mm plug tap and use a mill bit to dress the inside flush ,have done so many and all are still running

 

[Kentb of SWMO]

Use High Heat Red Loctite on spark Plug Thread inserts. Then use Anti-Seize on the Spark Plug Threads.

Kent

 

[souNdguy]

what about an antifoul adapter installed into the 'insert' repaired head, and then when you remove the plug, put a wrench on the antifouler to keep it from turning out.

IMHO.. I'd go 18mm myself.. I hate thread inserts..

soundguy

 

[aeromaster1]

if your talking Kohler L head engines,check the price of new heads,not that bad considering the hassel helicoil is giving you