Spark Plug Install Instructions

Just finished up. Hood open to hood closed in 2 hours flat, with at least 30 of that for battery/airbox removal/replacement (battery tie down system is so horrible IMO). I only hit one snag- I unclipped the wire harness from both driver's side coil packs, and in the process snapped off the little tab on the coil packs that the wire harnesses clip on to. Hope this doesn't cause an issue down the road...

 

2 tools I couldn't possibly imagine doing this job without: Gear Wrench Swivel Spark Plug socket, and Harbor Freight's Flex Head Ratchet. These fix 98% of the clearance issues people describe here.

 

For what its worth, I found the passenger side rear to be much, much more difficult that the driver's side rear.

I second this^^^^ I swapped plugs in a matter fo minutes both side mostly b/c of exp and knowing that all i need is that Harbor Frieght tool and the 1 3/4 inch extension. Also not engaging the drive lock into the extension but inserting it just enough to turn the socket.

Just a small update- I have an issue that developed either simultaneously with changing the spark plugs, or shortly afterwards, although it may have nothing to do with that job- its hard to tell. I'm burning a tiny amount of oil- so tiny I wouldn't be able to tell from the dipstick, but I can smell it especially after running hot. Additionally when I open the hood I can see the occasional puff of smoke coming from very near the rear passenger spark plug- but of course this is also near the turbo, which may be the culprit. Anyway, I'm going to be tracking this problem down soon (today?), and if anyone else has developed this problem post-spark plug replace, I'd love to hear about it.

^ are your CV boots spewing grease onto the exhaust by any chance?

Hah, that's the first thing I thought, but I just did the passenger side CV about a year ago and the driver's side looks fine.

Turns out its the not-uncommon valve cover gasket leak.

Turns out its the not-uncommon valve cover gasket leak.

 

Thanks. I couldn't remember which thread this was on (saw it briefly). I have exactly the same issue, including the slight bit of smoke at times, and the bad smell - been using the recirculated air setting for the AC for months now... Great to have confirmation!

 

Guess I'll get to working on the valve cover gaskets..

Leaking power steering pump can also cause a strong oil burning smell. It's also very common. Easy fix with an oring. Gotta take a look to know...

Leaking power steering pump can also cause a strong oil burning smell. It's also very common. Easy fix with an oring. Gotta take a look to know...

 

Thanks - good to know!

 

Someone already checked my car awhile back and reported leaking valve cover gaskets, so I'm assuming that's what it is, but I wanted some corroboration that it could cause the smell..

 

But, I should probably also check the PS pump.

Very helpful thread. Quick question. Is a knuckle extention the same as a universal joint extention? Thanks

Yes.

I certainly appreciate the write-up on the plug change, certainly made the job go quicker! I am by no means a stranger to tools and an engine compartment, but this is the first 'major' engine maintenance I have really done in the 8 years/92K miles I have owned my car. I was having fits of misfiring whenever my car would sit for a day when it was cold and damp. The misfires would last anywhere from a few seconds to a couple minutes, so I knew I was in need of new plugs at a minimum.

 

I purchased up a set of Autolite Double Platinum plugs (APP3924) and a set of Napa Belden Edge wires (BEL 700063) and hit the garage. From my experience on my 2.5i there is no need to move the fuse box, plenty of clearance using (2) 3" extensions getting down and pulling back out. Taking my time and sopping out oil from two of the plug tubes it was ~1.5hrs, not too bad for a first time. Two of the spark plugs were shot pretty good as can be seen below. Measured gap was .085" on #1 & #4, while the gap was .046" on #2 & #3, kind of strange, but the way it was. I gapped the new plugs to .039", down from the .045" they came out of the package with. Little bit of anti-seize on the threads and in they went.

 

I checked the resistance on the original wires and compared to the new units, there was a slight improvement on the new units, as expected. The longer, driver side original wires measured ~14Kohm vs ~10Kohm for the Napa units. The shorter, passenger side original wires measured ~10Kohm vs ~7Kohm for the Napa units. What was nice is the Napa wires were all numbered just like the OEM units, so it was virtually impossible to mess that up.

 

Car fired on the first turn and ran quite well. Glad someone mentioned it was 'normal' for the engine to die when coming to a stop. Mine did this every couple of stops for ~18 miles, then suddenly kicked back to a normal idle level, so I am guessing that was the ECU going through its relearning procedure. Been fine since.

 

Two of the four plug tube seals are obviously shot, but that project will have to wait for a later date at this time. I had a good 1" or so of oil at the bottom of tubes #2 & #3, while tubes for #1 & #4 were completely dry as evidenced in the pics below as well (i.e.- threads).

Sounds like a good replacement cycle. Based on years of Subaru ownership, you might want to rethink the Autolight plugs. Subarus thrive on NGKs both for spark-fire and longevity.

I have had good luck with Autolite units with my other vehicles, including a 2002 Forester, so hoping the same will be true here. I do know certain makes are 'sensitive' to certain mfg plugs and will be paying close attention to things over the coming months. Current vehicle replacement plans are for a new ride in May 2016, so I will be hauling around my wagon for another 16 or so months. Still trying to decide on what to replace her with, certainly something with similar size/utility/capability. Have to see what the 2016 units will be offering up.

Most subaru people agree - NGK, what is in the owner's manual only.

It's also in the FSM

Took me 5.5 hours. It is a PITA with the stupid air pump emissions thing. Had to do driver rear plug with car on lift because I didn't know how to disconnect the plastic tube from the air pump. At least the rear coilpack can be removed if you turn it just right.

Took me 5.5 hours. It is a PITA with the stupid air pump emissions thing. Had to do driver rear plug with car on lift because I didn't know how to disconnect the plastic tube from the air pump. At least the rear coilpack can be removed if you turn it just right.

 

^THIS!

 

Boy does it suck on the drivers side. The one closest to the grill wasn't terrible, took me some time to get the rotation on the coil right, so it would slide right out. But that rear drivers side, what a pain.

 

First off, the walkthroughs I had seen made no mention of that air pump hose. Not sure if it was new on the later models, but there was next to no way for me to get my fingers down there to do anything. Couldn't see or get a socket on that rear coil. And as far as disconnecting the air pump hose, I couldn't even get close to reaching the rear most clamp on that hose to disconnect it. I thought about just spraying a little power lube and try twisting it off, but cringed at the thought of getting it back on.

 

 

So what I did was take the bolts off the air pump itself, then disconnect the forward most clamp on that air hose (there is a bolt to remove, holding the hose to the motor as well). Doing that, there was enough play between the two, to wiggle the front of the hose free from the pump. (I really couldn’t figure out how to get the pump free of the shield over the front of it and just get it out of the way entirely, so the pump stayed in place). Once the hose was free, its flexible enough at the back end to just lift hose up and out of the way. This gave me just enough room to see the rear coil.

 

Used a swivel socket to get the coil bolt loose, but then I didn’t have a chance at getting the coil off. I could get my fingers on it, but the back of my hand was against the frame and I couldn’t pull it at all. I spent probably an hour between actually getting to the coil bolt and then trying to get it free. Wasn’t until my wife came down asking what was taking so long, had her use her tiny hands and pop it free. Similar to the forward coil, took me some fooling around before I spun it correctly to lift free between the head and frame.

 

Getting the plug wasn’t too bad, used a swivel spark plug socket and extension. Just makes me a little uncomfortable torqueing that thing free at an angle. And the same goes for threading the new one back in. Took me a little while before it actually started threading in. Had to the swivel socket and extension again. Just couldn’t fit my hand down there.

Thankfully it’ll be a couple years before I have to do it again.

Best bet, get a girlfriend with tiny hands for the week. It'll make the job a lot less miserable.

Best bet, get a girlfriend with tiny hands for the week. It'll make the job a lot less miserable.

 

I'm on board with this, but I don't think my wife would be too happy with that solution. Plus it would cost more than just taking it to the dealer, both for girlfriend for the week and the marriage capitol that I would have to spend for the rest of my life

^THIS!

 

Boy does it suck on the drivers side. The one closest to the grill wasn't terrible, took me some time to get the rotation on the coil right, so it would slide right out. But that rear drivers side, what a pain.

 

First off, the walkthroughs I had seen made no mention of that air pump hose. Not sure if it was new on the later models, but there was next to no way for me to get my fingers down there to do anything. Couldn't see or get a socket on that rear coil. And as far as disconnecting the air pump hose, I couldn't even get close to reaching the rear most clamp on that hose to disconnect it. I thought about just spraying a little power lube and try twisting it off, but cringed at the thought of getting it back on.

 

 

So what I did was take the bolts off the air pump itself, then disconnect the forward most clamp on that air hose (there is a bolt to remove, holding the hose to the motor as well). Doing that, there was enough play between the two, to wiggle the front of the hose free from the pump. (I really couldn’t figure out how to get the pump free of the shield over the front of it and just get it out of the way entirely, so the pump stayed in place). Once the hose was free, its flexible enough at the back end to just lift hose up and out of the way. This gave me just enough room to see the rear coil.

 

Used a swivel socket to get the coil bolt loose, but then I didn’t have a chance at getting the coil off. I could get my fingers on it, but the back of my hand was against the frame and I couldn’t pull it at all. I spent probably an hour between actually getting to the coil bolt and then trying to get it free. Wasn’t until my wife came down asking what was taking so long, had her use her tiny hands and pop it free. Similar to the forward coil, took me some fooling around before I spun it correctly to lift free between the head and frame.

 

Getting the plug wasn’t too bad, used a swivel spark plug socket and extension. Just makes me a little uncomfortable torqueing that thing free at an angle. And the same goes for threading the new one back in. Took me a little while before it actually started threading in. Had to the swivel socket and extension again. Just couldn’t fit my hand down there.

Thankfully it’ll be a couple years before I have to do it again.

Best bet, get a girlfriend with tiny hands for the week. It'll make the job a lot less miserable.

 

 

Post #595 would have saved you a lot of work.

It has been a while since I changed them, but other than being time consuming, it isn't that bad a job. The suggestions here walk you right through the procedure. I did one side one afternoon and the driver's side another. Easier on my aging back that way. I had a bit of trouble starting one of the plugs and ended up using a small screwdriver to pry the plug up a bit to get it lined up to start the threads.

 

john

I have a stock Legacy GT, and I was sent one step colder plugs. Would there be any issues if I run these? I don't plan on being above Stage 1 anytime in the near future either.

Get the right heat range.

^This. Unless you're tuned for the colder plug, go with the stock plugs.

^THIS!

 

First off, the walkthroughs I had seen made no mention of that air pump hose. Not sure if it was new on the later models, but there was next to no way for me to get my fingers down there to do anything

 

You missed mine then, post #589, page 40. '08 5EAT - 2ndary air assist pump hose. There is a hose clamp at each end with a bolt holding it to the block near the front. The pump itself doesn't have to be removed, but of you want to, you have to remove an electrical harness with a "quick-disconnect" type of connector. Pinch tab is on the bottom. Then 2 bolts to get the pump off. Its tight so you have to be careful when you slide the front part of the assist hose back into its flange. Glad you got it. Time for me to do mine again Did it for the second time today. Car purrs. Idles great.

Edited May 18, 2015 by shadowsports