Question about replacing Yamaha Spark Plugs

[byron.akhavi@gmail.com]

Have a quick question regrading Yamaha outboard spark plugs. Do you guys clean the mating threads before tightening to spec.?? Do they need to be cleaned before tightening the plug?? I just remove and insert a new plug (properly and I do not cross thread). The plug is installed by hand using a spark plug starting tool. Then I torque to the 13 lb.-ft. spec. using a digital torque wrench rated for 20 lb.*ft max range.

I install as per NGK requirements. No lube applied as directed on the instructions. Never cleaned the mating threads and use a new plug and check gap (always correct as per Yamaha spec.). Should mating threads be cleaned before applying torque??

[99yam40]

tell me how you would clean those threads if you did

[DennisG01]

If ANYTHING, I'll wipe the hole with a rag. I have never, in all my years, done anything more than that. I have also NEVER used a torque wrench on spark plugs - by feel only. Never knew there was a spark plug "starting tool", either! I just my built in tool... my fingers! In the case of hard to get to plugs like on an inboard V6 (the middle ones are sometimes tough depending on what brand manifold), I just use a short piece of rubber hose over the insulator.

[99yam40]

back when the plugs had crush washers, you just turned them a little more after finger tight.
now a days without the crush washers and the heads being aluminum, it is best practice to toque them properly if you do not have a good feel for tightness.
after pulling them from a motor there is a good chance, they have some lube on the threads.
and if there are signs of carbon that may have flaked off when pulling the plugs, I will spin the motor over some to hopefully blow any inside the cylinder out

[zenoahphobic]

Dry, the head thread tends to grind away a bit.
With two strokes oil tends to wind it’s way up the threads. Purists will tell this may be a sign of leakage past the seal/head of the spark plug that requires more torque than “guess tight”.
I’ve never worried about this oil but if lubrication is used torque should be a little less. Again dry thread anywhere, “antisieze” is more a good idea than a bad idea.
Also I’ve never seen a tool to clean the inside thread; plugs of course can be brushed and dipped in solvent.

[Keithbaja]

OMG. Tool is called "spark plug thread chaser". Have had many for 40+ YRs...

[brian3006]

OMG. Tool is called "spark plug thread chaser". Have had many for 40+ YRs...

wow never knew such thing existed nor had a need for one... Good to know though

[boscoe99]

Then I torque to the 13 lb.-ft. spec. using a digital torque wrench rated for 20 lb.*ft max range.

Winner winner chicken dinner.

A breath of fresh air.

Thank you, thank you, thank you.

[boscoe99]

https://www.amazon.com/Lisle-20020-L...a-561914302730

[robert graham]

Maybe that thread chaser tool is made for spark plug threads that have been cross-threaded?……best rule is to use your fingers to insert and engage the plug for several threads before tightening with a plug wrench. I always wire brush the spark plug threads after sand-blasting all carbon from plug, then one drop of oil on threads before installing…..

[HMBJack]

No lube on spark plug threads? I never heard of this...

I always put the silver anti-seeze grease on the threads.

[robert graham]

No lube on spark plug threads? I never heard of this...

I always put the silver anti-seeze grease on the threads.

Anti-seize is probably the best, but I’ve always just used a drop of oil….

[zenoahphobic]

OMG. Tool is called "spark plug thread chaser". Have had many for 40+ YRs...

I think we were talking about a “softer” tool, a tool that wipes the thread clean and dry, rather than a thread chaser that is essentially a thread cutter.

[TownsendsFJR1300]

https://ngksparkplugs.com/en/resourc...ut-spark-plugs

[zenoahphobic]

Yes I completely forgot about heat transfer needed from the plug to the head.
Still with NGK plugs, I have found they still stick in some engines, heat range can be changed if anti seize creates a problem with heat transfer.
I own about 40 spark plugs in going vehicles etc! But I also tend to have little interaction with them as plugs and engines are now very reliable requiring quite large service intervals.I don’t fix things that aren’t broke.