David98GS

Hey guys,

I just had a question regarding spark plug replacement. I just changed them yesterday and I know I tightened some all the way without over tightening them, but some I tightened and still gave them a little extra room to be tightened more. Is that ok? Since it has an aluminum head it just freaks me out to tighten them all the way down and I would hate to go back in there and tighten them more. We went for a test drive yesterday and it seemed to be doing well. I did notice the old plug threads seemed rusted a little and thus making them a little harder to remove. Any ideas?

Thanks for your help!

tomtnc

I replaced my plugs this past weekend for the 2nd time in the four and a half years that I've owned this car . For an aluminum head, I always put a smigin' of anti-seize lubricant on the threads of the plug and tighten the spark plugs 1/4 turn past contact with the head after finger tightening. In the past 20 years of owning aluminum-headed vehicles, this method has never let me down.

**NEVER remove or install spark plugs with a hot or warm engine...be sure the engine is at ambient temperature before attempting this job...I recommend letting the car sit overnight and attempt this job first thing in the morning**

David98GS

Hmmm..well the thing is..I think the threads on the threads on the head are corroded or rusted from the heat, becaus the plugs feel hard to get in..I twist the plugs in to what I think is when they have contact, but then I can still turn them with my socket wrench relatively easy. This is how I have always changed plugs..take out old ones and put new ones in with anti-seize and tighten them until there is no movement, but do not overtighten. Some I left a little loose, because I started to think I might strip the head. If it ever was stripped is there anything you can do to fix it?

Thanks guys!

macd7919

iTrader: (10)

If you want to do it the correct way, put anti-seize on the threads and torque the plugs to 18 ft/lbs. That provides adequate holding and proper heat transfer.

JeffTsai

iTrader: (1)

Macd7919 is right on the money but I just want to add a few things.
1. Clean up the spark plug hole before putting new plug in. A lotta dirt/oil/grime builds up in there over time.
2. Make absolutely sure you don't get any of the anti-seize on the spark plug electrodes.
3. When torquing down the plugs. I recommend you get an high accuracy torque wrench. Trust me, it's a very worthwhile investment if you plan on doing alotta DIY work on your car. And I'm talking about an accurate one like craftsman or Snap if you have the money lol. Don't trust the $15-20 Autozone specials for any critical engine work. Personally I have 2 sets of torque wrenches. One is a high quality craftsman I use to rebuild motors, and a cheap Autozone one to tighten wheel lugs

David98GS

Yeah, I do need a torque wrench, but since I don't have one..is it ok to just tighten the plugs down until they can't move with my socket wrench? I never tighten past that. I just tighten them with my fingers and once it starts to get threaded in I finish tightening with my wrench until there is no longer movement. It seemed that's how tight the ones I took out were.

And thanks for the help guys!

TRD911

I think what your feeling is the crushable gasket crushing.

Just like when you remove the drain plug on the trans or rearend that gasket seals by crushing. If your not mechanicly inclined and cannot "feel" what is going on then YES you need a tourque wrench I always go by feel.

ALWAYS ALWAYS ALWAYS USE ANTISEIZE WHEN YOU HAVE TWO DISLIKE METALS (ALWAYS ON STAINLESS) BEING SCREWED INTO EACH OTHER.

NEVER PUT THE PLUGS IN WITH OUT ANTISEIZE.

David98GS

Well, I have always changed my own plugs on the cars I've owned and on all of them I have used the same method. Thread them in by hand and then finish tightening with a socket wrench until there is no movement...I have never had a problem. I know plugs should be changed about every 60,000 miles so I guess I won't need to go back in there soon, but hypothetically speaking if the head did strip is there any way to repair it?

Thanks guys!

David98GS

Also, there was no real resistance when I was doing this..they were tightening easy and then I just couldn't tighten anymore so I stopped. Isn't still safe to tighten until the crush washer can not compress anymore and thus not allowing the plug to be tightened anymore? It's just a pain to go back in there and check all 8 again..never had to do so much work to replace plugs on my Infiniti.

JeffTsai

iTrader: (1)

David, the plugs used for the GS have crush washers on them. I think the basic instructions are to tighten as much as you can by hand(like finger tight), but without the ratchet tool. Then once it stops moving, use the ratchet and tighten it 1/4 turn more. I think that's what it says on the spark plug box.

David98GS

I did tighten with my fingers and then a little with the ratchet, but the spark plug still tightened rather easy. I thought that the only reason I couldn't tighten anymore with my fingers was because the threads are corroded and have junk in them. You don't by any chance happen to own a shop so you can check them do you? I live in DFW. I can expose the plugs..I just don't have a torque wrench to tighten them back up.

Thanks for the help!

David98GS

Ok, just purchased a torque wrench and I set it at around 10 ft. lbs. or maybe a bit more (I tested it on my infiniti) but it seemed as though that was pretty tight. Did I not have my torque wrench set right? It's the one with the handle you can adjust. After I used it I decided to use my regular socket wrench and take it off, because I thought it was too tight and it seemed as thought it took longer for the spark plug to come out! (at this point I thought it was stripped) also, when I went to tighten it, it also seemed longer for it to go back in. Is this because when I use a torque wrench it torques down the washer more than where it was at originally?

Thanks guys!

Lexamatic

Has anyone taken pics when they did a GS400 plug change?

LextacyGS4

iTrader: (2)

All i can tell you is that taking it in and out is only making it worse. You should just leave it in and not worry about it.

my question to you, if you have a GS300, I was doing this yesterday and only found three plugs, i couldnt find the other three. Where are the located?