Hi All---

I've replaced probably hundreds of spark plugs in my cars and trucks over the years---In US domestic iron, and German and Japanese aluminum heads---These are the tightest I can remember removing. (It's been a while since I removed any that hadn't gotten some anti-seize)

I'm at 103,000 miles, a bit past the replacement time, but it runs like a top (now that I cleaned the throttle-body!) The engine compartment is pretty clean---some dust, but next to no greasiness. Everything under the snap-on shroud is clean---no corrosion.

I have walked up to the line in the amount of effort that I feel comfortable using to remove these plugs.

I'm considering a squirt of penetrating oil down each spark plug tube and letting it sit overnight. This Mazda is also the most modern vehicle (2010) I have ever worked on (or owned.) Do I risk some reaction or contamination that would mess with the computer's sensors or some other thing?

Many Thanks!

JW

 

Definitely drown the plugs in penetrating oil. Also the next day, wind them out 1/4 turn, then back in, wind out 1/2 turn, wind back in etc etc

Once they are out, crank the engine over to blow out any residue without engine load.

 

Excellent, Thanks!

Glad I let it lie...

By the way, this 2.5 has the best access to the plugs of any engine I've worked on!

JW

 

Hopefully all it is carbon on the threads. I would follow what grim_reaper recommends.
DON'T FORCE...... or you may damage the threads or completely strip it. In which case you will need to time-sert a spark plug hole
I would recommend to purchase a spark plug thread chaser before you install new spark plugs.

You are a good reason why I always suggest for people to change their spark plugs much sooner then the FSM and more so when your engine is over 50k miles.

 

I think I have a fairly good feel for the amount of force that's safe to apply---I didn't get even the tiniest movement and abandoned the attempt.
I've never forgotten having to pay to have a helicoil inserted into my '67 VW bus...PO error, mine to pay for...on an 18 year old's budget!

I've never seen or heard of a spark plug thread chaser---I'll look into it. Thanks, Callisto.

JW

 

Here is one of a few I have on hand for spark plug thread chasing.




I highly recomend with any damaged thread to do a permanent thread repaid using a Time-sert. I keep a large section of Time-sert and thread remover/ extractors mostly for DIY customers, friends and family that had troubles...... hahaha!

 

Awesome!
I'll look into Time-Sert, too.
Fingers crossed for no thread damage.

JW

 

I soooooooooo agree with this. !!!!!

 

FYI : Spark plugs for the 2010 2.5 should be changed every 60,000 miles / 100,000kms.

So either they have never been changed and are just rusted in place or some ******** over-tightened them when the replaced them.

 

Could be either one!
I bought the Mazda with 61,000 miles on it, and it looked brand new. The engine compartment was spotless.
Supposedly newly tuned-up.

Could I give the plugs a couple squirts of PB Blaster, drive it bit, and repeat for a few days?
Thinking the heat/cool cycle plus the engine vibrations might work it in?

JW