Spark plug threads

[lefty]

Toro 20370 - 313006249

Kohler PG-XT675-2034
4225607048

There's always something. This was going to be an easy service but whoever put the spark plug in last failed. The plug had resistance the whole way out and when I examined it, it was clear they crossed it up on the way in. The new plug hits resistance shortly after engaging the threads. I haven't tried to force it at all.

What are my options? Can I try chasing the threads? Helicoil? New head maybe?

Thanks

[RoyM]

The Kohler XT675 is a Chinese knockoff and uses an oddball metric thread that only accepts the OEM plug. I don't know if you will find a helicoil to match, you might install a standard 14mm insert and use a regular plug.

[lefty]

The parts list shows Kohler 14 132 11-S
The one that was in there was 14 132 11
Not sure what the s means.

The one I got was a replacement, NGK DCPR6E. It looks identical to the Kohler.

Here's a pic of the thread damage on the plug.
https://photos.app.goo.gl/uAWEnNVEc6arFCNY8

[KE4AVB]

Doesn't looks like cross threading to me. More like carbon damage from carbon fouling of the threads. So ran a M12-1.25 tap thru the hole and see if that cleans it up.

BTW the hole is a M12-1.25 thread as I just got thru checking the head here.

So the DCPR6E is correct plug as is the Champion RA8HC.

Now note the Kohler plug on some of these engines do take a 17mm soccket instead of the 16mm (5/8).

[38racing]

bottom threads certainly don't look as sharp as the top ones.

[lefty]

It's definitely screwed up. I have that tap so I'll run it through there and hope for the best. I guess I'll use some grease to catch any metal filings? Fortunately, the angle is horizontal so I should be able to catch most of it. I may even tilt it forward and take advantage of some gravity.

Thank you.

[38racing]

It's definitely screwed up. I have that tap so I'll run it through there and hope for the best. I guess I'll use some grease to catch any metal filings? Fortunately, the angle is horizontal so I should be able to catch most of it. I may even tilt it forward and take advantage of some gravity.

Thank you.

I've read about filling cylinder with shaving cream and then sucking it back out.

[38racing]

The Kohler XT675 is a Chinese knockoff and uses an oddball metric thread that only accepts the OEM plug. I don't know if you will find a helicoil to match, you might install a standard 14mm insert and use a regular plug.

https://www.bantasaw.com/catalog/viewpr ... i=&p=10099
possibly different ug before 2012?

[lefty]

I don't know if this is overkill but I guess I could remove the head and do it on the bench. But that might be opening up a bigger can of worms.

[KE4AVB]

With head being Aluminum use rubbing alcohol on the tap as grease or oil will cause the tap to jam. Plus also so far at a time and back to clean out the chips and reapply the alcohol.