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H6 Plug Change: Not quite as bad as it is hyped to be.

30429 Views 40 Replies 16 Participants Last post by  lesstutrey
I almost got scared off from reading others' horror stories on the H6 plugs, but I tried it anyway. Tackled this yesterday in just under three hours. I don't think anyone can ever have enough tips on this, so here's mine. A few are probably repetitive:

- Do it from the bottom. I just can't see doing it from the top. My guards are already gone from underneath, so the plugs are right there. No moving the washer fluid reservoir or air intake, killing your back leaning over an engine for hours, or nonsense like that.

- Start with the plug closest to the steering wheel. This is definitely the hardest. If you can tackle this one, you can definitely handle the rest. The passenger's side backmost plug was easier, but that might only be because I had a method down from the other one...I'm not sure if there's actually more clearance.

- You absolutely need a 3" extension or smaller. Bigger ones will do you absolutely no good. I got by with a single 3", a deep socket, socket for the bolt on the coil packs (12 mm?--Can't remember for sure) a swivel adapter, and a standard 3/8 drive ratchet. A smaller extension would have saved me time.

- A swivel-adapter (U-Joint) is somewhat helpful for the back two plugs, but it's not absolutely necessary. I realized it helped a little bit on the passenger side backmost plug, but I didn't use it and still got the driver's side out.

- Definitely use some sort of anti-seize on the threads. I don't know when mine were last done, but some of them didn't turn too easily for quite a few turns and there was evidence of neverseize on those threads. I can't imagine what they might have been like without it.

- As mentioned in other threads, fuel line could be helpful to loosen the plugs but don't rely on it. I couldn't have turned some of mine with it until they were already most of the way out.

- Make sure your ratchet is easy to free from the extension/socket. The reason is you'll need to free it from the extension when the plug is about halfway out, otherwise you won't be able to get the extension out.

- Cold engine is a must. Don't even try it on a hot or warm engine.

- Pliers can be helpful to free the coil pack from gripping the plug if used gently (there's not much room to pull with your hand), but be VERY careful of the plug and wires on the coil pack--it would be bad to destroy them.

- Do it on a warm day or in a heated garage. Numb hands will make the job nearly impossible.

- Be careful of the o2 sensor wires. I could definitely see potential for destroying them with a swing of the ratchet.


All in all, it's really not THAT bad. A lot worse than a V6 for sure, but if you're used to doing your own work give it a try before paying $250+ to have it done. Set aside a few hours (I'd guess just about anyone could have it done in under 4...I did it in just under 3 and am not even all that mechanical). Of course, any number of things could add considerably to that time.

Good luck! Also post any other tips you've got here!
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I almost got scared off from reading others' horror stories on the H6 plugs, but I tried it anyway. Tackled this yesterday in just under three hours. I don't think anyone can ever have enough tips on this, so here's mine. A few are probably repetitive:

- Do it from the bottom. I just can't see doing it from the top. My guards are already gone from underneath, so the plugs are right there. No moving the washer fluid reservoir or air intake, killing your back leaning over an engine for hours, or nonsense like that.

- Start with the plug closest to the steering wheel. This is definitely the hardest. If you can tackle this one, you can definitely handle the rest. The passenger's side backmost plug was easier, but that might only be because I had a method down from the other one...I'm not sure if there's actually more clearance.

- You absolutely need a 3" extension or smaller. Bigger ones will do you absolutely no good. I got by with a single 3", a deep socket, socket for the bolt on the coil packs (12 mm?--Can't remember for sure) a swivel adapter, and a standard 3/8 drive ratchet. A smaller extension would have saved me time.

- A swivel-adapter (U-Joint) is somewhat helpful for the back two plugs, but it's not absolutely necessary. I realized it helped a little bit on the passenger side backmost plug, but I didn't use it and still got the driver's side out.

- Definitely use some sort of anti-seize on the threads. I don't know when mine were last done, but some of them didn't turn too easily for quite a few turns and there was evidence of neverseize on those threads. I can't imagine what they might have been like without it.

- As mentioned in other threads, fuel line could be helpful to loosen the plugs but don't rely on it. I couldn't have turned some of mine with it until they were already most of the way out.

- Make sure your ratchet is easy to free from the extension/socket. The reason is you'll need to free it from the extension when the plug is about halfway out, otherwise you won't be able to get the extension out.

- Cold engine is a must. Don't even try it on a hot or warm engine.

- Pliers can be helpful to free the coil pack from gripping the plug if used gently (there's not much room to pull with your hand), but be VERY careful of the plug and wires on the coil pack--it would be bad to destroy them.

- Do it on a warm day or in a heated garage. Numb hands will make the job nearly impossible.

- Be careful of the o2 sensor wires. I could definitely see potential for destroying them with a swing of the ratchet.


All in all, it's really not THAT bad. A lot worse than a V6 for sure, but if you're used to doing your own work give it a try before paying $250+ to have it done. Set aside a few hours (I'd guess just about anyone could have it done in under 4...I did it in just under 3 and am not even all that mechanical). Of course, any number of things could add considerably to that time.

Good luck! Also post any other tips you've got here!
How many miles on the plugs you removed? What made you feel they needed changing? What plugs did you go back in with?

I'm one of those people that try to talk myself into paying someone to do it. Then you also read how it's easier if you're also chaging valve cover gaskets - maybe I can wait till they start leaking! My wife's car still has factory plugs in it - only 65K miles. Should I wait till they start misfiring regularly?
I actually don't know how many miles they had on them...that's why I changed them. I didn't think I would do them until spring, but we had a warm day and I had the entire day free, so I took advantage of it.

The car has 110K on it, but I don't know if/when they were changed. They didn't look too horrible and I haven't really noticed a difference in power (don't know about MPG yet) but at least I'm good for 60K (3 years or so) now.

I used the same as stock. NGK platinums. They're supposed to go 60k according to Subaru, but realistically they probably would last longer than that without any issues. No matter what you do, stick with NGK, but you could use iridiums instead if you wanted since they'll go 90k. I went with the platinums because advance had everything 20% off this weekend and didn't carry iridiums.
Actually, I'm ashamed to say I already have the NGK Iridiums and, uh, they've been hanging around for quite a while. I got them when her car was throwing misfire codes - ended up being a bad battery. Only 65k but almost 10 years. maybe I'll tackle that job in April. I've never changed plugs in a DOHC car of any type and also have no experience with coil-on-plug.

thanx
The coils are nothing difficult. The only automotive plug changes I've done have been on distributorless engines. Just a little pulling and such to free them from the plug (and that's only because of the space and angle you're given to work with on a Boxer), but nothing bad at all.
do you have to tie them up outta the way ?

is there a procedure with pics somewhere?
Like there's any room to take pics!

Maybe with a borescope...


quit it.

I'm frightened enough as it is.


hah!


Glenn, in this pic; https://picasaweb.google.com/108104...uthuser=0&feat=directlink#5682473083807047170

it LOOKS like one side has 10 bolts and one has 11. just wondering because, some folks have suggested trying to just tighten the valve cover bolts a little to stop/slow leaking. I figured I would if/when I try swapping plugs next spring. And, are they all 10mm heads? any hidden under a bracket or ??? that would need to come off?
sorry you didn't get through it, I easily spent 1/3 of my the total time on the left rear one the first time, for some reason, I just couldn't get the puzzle piece-coil rotated correctly to go back on - had to jack the engine up a little. But the second time it just went like magic and was no harder than the others.
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