Jump to content

Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse

- - - - -

All about changing Spark Plugs.

  • Please log in to reply
4 replies to this topic

#1 syphon


    Subaru Fanatic!

  • Members
  • 423 posts
  • Kirkland

Posted 07 December 2003 - 07:02 PM

Hey everyone, I have two questions.

The first one, I want to know if the symptoms I'm having could be caused by a fouled spark plug.

The second one, I want to know what spark plugs you guys use, how to gap them, and what to torque them to (basically how do I change my spark plugs :-))

I dont know how many of you saw this thread

but basically a spark plug shot out of the hole and stripped the threads on its way out. I was going to Helicoil it myself, but due to no garage and bad weather (not to mention laziness) I just took it to Smart Subaru Service in WA.

So now my car is all repaired, but I'm still having some small issues.

Whenever I turn my car off for even a few minutes, when I try to drive it again it drives like it's completely cold. The car will spit and sputter and will act like it's about to die unless I floor it and get the revs up. The wierd thing is, this happens regardless of the temp. I was on the freeway and had been driving for about 30 minutes when suddenly it started sputtering at a certain RPM level (say, 2500-3000).

This issue didn't happen before I had the repair job done. I THINK they just used my old spark plug, so I was wondering if you guys think this could be caused by a slightly damaged spark plug? It's possible that it was banged around when it shot out, and that they didnt fix it when they put it back in. It could also be my carb, but I'm hoping it's the cheaper problem right now.

Second... what tips do you have for changing spark plugs.
I've never done it before, but I can't imagine it'd be that hard. What plugs should I buy? How do I gap them? How tight do I put them in? Any tricks I should be aware of to avoid damaging the heli-coiled S/P hole?

Thanks in advance for your help!

#2 beauregaardhooligan


    Subaru Fanatic!

  • Members
  • 424 posts
  • Greenville, SC

Posted 07 December 2003 - 09:27 PM

Nothing but NGKs for Subarus.
Get a new set and replace them all.
Clean out around the old plugs best you can before removing them to keep crap from falling into the cylinder. WD-40 works well, but can be messy.
Use a gapping tool to set the gap to factory spec for your motor. Be very gentle with the new plugs, they are fragile and can break internally from just a short drop.
Put lots of anti-sieze on the threads of the new plugs.
Turn them in until they are finger tight. I like to turn them back and forth some to spread the anti-seize around. Then tighten them to the manufacturers spec.
I also use di-electric grease on both ends of the spark plug wires.
Go ahead and get a new set of wires while your at it.

#3 gravelRX


    Driven with both feet.

  • Members
  • 885 posts
  • Roanoke, VA

Posted 07 December 2003 - 10:51 PM

You can use an old piece of vaccum hose to get the spark plug started into the threads to make sure you don't cross thread it.

Put the hose on the top of the spark plug and get it seated in the hole, turn it counter clockwise first until it mates to the threads, then start tightening until the hose starts to slip.

Sounds corny, but it works. I second what Beauregaardhooligan said. Anti-seize is your friend.


#4 Setright


    Elite Master of the Subaru

  • Members
  • 3,176 posts
  • Denmark

Posted 08 December 2003 - 02:34 AM

Well, I use BOSCH Super "Ytrium Plus" plugs and find them to work just as well as NGK, but they last about twice as long!

Bear in mind, that I am in Europe and part types and availabilty are probably not the same as "across the pond".

Recommended torque is 15Nm, which essentially means tight enough to collapse the gasket and no more. It's a long, fine metric thread, and it will not loosen easily, so don't worry about under-torquing it. Just a firm hand and don't force it tight.

Bosch "Super 4", with four electrodes were not a success, by the way. And don't re-install a plug that you have taken out, the gasket is only good for one fitting.

#5 torxxx


    I void warranties

  • Members
  • 2,918 posts
  • Fairbanks

Posted 08 December 2003 - 02:16 PM

Just like the other guys said
Go buy NGK plugs.. ONLY USE THEM (Platniums are a lil nicer)

Get a plug gaping tool and gap then from .42 to .47
I believe NGK's are pre-gapped pretty close to what soobs need to run. Antisneeze those bastards and hand tighten them in.

If you have any mechanical sense at all, you can feel the threads starting to grab on the first 1/4 turn (hand tightening)

Also what kind of engine do you have?

And someone said something about dropping a plug. Never use a plug that you've dropped.. Chances are the guys at Napa or what ever store you goto have probably dropped the plugs once or twice already.. (A friend of mine had the electrode break out of the middle of his plug in his brand new 2003 RMK 800 snowmachine... needless to say, it seized the engine.. when we pulled the pistons you could see where the electrode and rings met..

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users