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Changed my sparkplugs today

Old 04-22-18, 09:34 PM
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Jabberwock
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Default Changed my sparkplugs today

Car has 105k miles on it. Changed the spark plugs today in anticipation of taking a 2,600 mile road trip later this summer. Started on the driver side, removed driver side plastic cover, engine cover already off, and all 4 old plugs on that side came out easy and and new ones went in very easy. Toughest location was first plug because the dip stick tube is partially in the way. Making the job a lot easier I used a gearwrench sparkplug tool, along with a universal knuckle, and attached to that various straight extensions on my socket wrench to get at some of the tighter angles required.

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Passenger side requires removal of air-filter box cover and the passenger side plastic box breather assembly that is attached to the throttle body. One bolt needs to be removed and then detach one thin hose and one larger hose to remove the plastic box breather assembly. First two plugs are easy in and out on passenger side. The last two are tighter spaces - third plug is tight on the passenger side fuse box, then the last rearmost plug is very tight on the battery case. Working carefully it was still not that hard to pull the coils, plugs and install new in those tight spaces using just the gear wrench with universal knuckle joint and various length extensions.

One critical item is to always reinstall the new plug just gently rotating gearwrench containing new plug by hand. They go in and screw down super smooth - gently finger tighten until you meet hard stop and then use socket about 1/2 to 3/4 turn or so until you feel the compression washer/gasket compress down. Do not over tighten. Manual says to use a torque wrench but limited access with my TW made that impracticable.

I used a very small flat head screwdriver to pry up (mostly sideways and out) the little locking tab that locks the electrical connector to each coil. This made getting the connectors off without damaging or pulling wire loose much easier.


First time plug change for the LS, doing the job going slowly and carefully, taking my time was just over 2.5 hours. If I had to do it again I could do it in 90 minutes.

Only surprise was the 3rd plug on passenger side was in only finger tight...likely from the factory. The plug looked different than the 7 others in that it had uneven color and wear pattern so I assume it may have had some amount of ignition blow by but not enough to throw a code.

Hard to believe Lexus wants supposedly quotes apprx $500 to do replace plugs.

Last edited by Jabberwock; 04-22-18 at 09:38 PM.
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Old 04-23-18, 01:16 AM
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Thanks for the instructions my mechanic charged me around $40 to replace them for me and he took about 2 hours doing so
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Old 04-23-18, 03:51 AM
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The correct torque setting is run it down with the impact. Or tighten it down until it starts to strip, then back a 1/4 turn
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Old 04-23-18, 04:33 AM
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Johnhav430
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Nice job, I'll wait until 120k, at 104k now....actually I would need the spark plug socket myself. I would prefer to use a torque wrench even though on another forum, there was a long debate, guys who build "race cars" said they haven't used a torque wrench in 40 years and it's unnecssary, any mechanic worth his salt can do it by feel lol Don't know if it's helpful here, but I have locking extensions of varying lengths, so the socket cannot come off...

I did use the tighten as far as it will go until it strips method on my parents' car when I was 17. I guess it wasn't any big deal, my dad had it towe d to the dealer and it was fixed. No idea what it cost...
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Old 04-23-18, 06:28 AM
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The plugs I used have a relatively soft metal compression washer/gasket on them.
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The plugs screwed in (by hand) very smoothly and it was very easy to tell when they had snugged up. Then it is actually very easy to feel the washer compress at the base of the plug and stop as you turn the extra 1/2 to 3/4 rotation with the socket (after plugs is finger tight). Given the close tolerances involved and the very low torque setting (17 ft/lbs) I trust my experience and feel snugging down by hand way more than trying to use my 1/2 inch torque wrench which is high quality but I bet not super accurate at such a low setting. It is much better than feel at getting 82 ft/lbs on the lug nuts.
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Old 04-23-18, 06:44 AM
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Originally Posted by Jabberwock View Post
The plugs I used have a relatively soft metal compression washer/gasket on them.
https://www.amazon.com/gp/product/B00LVALKHK/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

The plugs screwed in (by hand) very smoothly and it was very easy to tell when they had snugged up. Then it is actually very easy to feel the washer compress at the base of the plug and stop as you turn the extra 1/2 to 3/4 rotation with the socket (after plugs is finger tight). Given the close tolerances involved and the very low torque setting (17 ft/lbs) I trust my experience and feel snugging down by hand way more than trying to use my 1/2 inch torque wrench which is high quality but I bet not super accurate at such a low setting. It is much better than feel at getting 82 ft/lbs on the lug nuts.
Gotcha, the BMW as well wants 17 ft. lbs. Your torque wrench would likely need to have an upper range of no more than 75 (mine is a 3/8 5-75), because torque wrenches are inaccurate below 20% of their upper range. We had this huge never ending thread on the BMW forum years ago where someone stripped all 6 cylinders, and said his torque wrench was from work, was really high end and had a range of like 1-20 ft. lbs. with a NIST calibration, so no way at all he overtorqued (everyone said not rocket science only way you stripped all 6 was too much torque).

Dug a little deeper and found he had applied anti-seize (the mfg clearly states not to as the plugs have a coating). He still insisted it was not the anti-seize and maybe it was in fact his wrench that was bad, so it was recalibrated and found to be accurate. Everybody gave up, and said ok dude it's BMWs defect, we agree with you. But actually I think the guy was like many of us and really wanted to find out why this happened, and he admitted in the end it was the anti-seize that he had applied...mine too has a calibration cert so it's good enough for me, and I don't recalibrate so who knows...

But that thread flushed out so many people, some who said look I've been building race motors for 40 years so if you need a torque wrench you might as well keep your work limited to your home garage..lol
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Old 04-24-18, 01:47 AM
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I've got to do 2 knock sensors so this is a handy little write up for me. Plugs and coils at the same time methinks
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Old 04-24-18, 11:50 AM
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Never heard of anti-seize doing that. Have always (at least for fifty years) set spark plugs by feel. I use a very short ratchet and grip the head of the wrench while tightening to snug. This is for aluminum heads. I use a DROP of anti-seize.

I think what may have happened to the BMW is he stripped the threads taking them out. Very common with some engine designs and why it is smart to replace spark plugs at about 50 K miles. I sometimes shoot PB Blaster down on the spark plugs before removing them. I do this when the engine is warm.

Believe it or not, some Ford engines need the cylinder head replaced if the plugs are to be removed. It is that bad.

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Old 04-24-18, 09:42 PM
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My plugs in the LS had been in for 105k miles - I was also concerned the plugs might be difficult to break loose and remove since they had been in for 12 years and 105k miles but they came loose very easy and screwed out very smoothly. Actually one of my plugs - the 2cd to rear-most on passenger side was in only hand tight. It came out without any resistance at all. Weird because the plugs had never been touched since the car was brand new so it must have been installed without snugging the compression washer at the factory. For 105k miles the engine ran smooth as silk despite the slightly loose plug. I have noticed that changing plugs the engine seems even smoother now - honestly difficult to tell engine is even running at stop lights.
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Old 04-25-18, 06:06 AM
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Waiting to 120k to do the job, but not looking forward to it lol Sure it will be fine. Having only a 1 car garage, whenever I am working on a car outside, I make sure that at least one car is on the street, just in case (we have a pad so those cars cannot get past a car in the driveway).

I agree with all....likely by feel is a sure fire way that things would be ok. With a torque wrench, in theory, it's better, but there are other factors. Putting anti seize then setting to 17 ft. lbs. will cause the torque wrench to be off. The drain plug on my wife's car is a lesson in doing by hand. I should not have been using a 1/2" ratchet last Sat. When I redid I switched to 3/8". That tapered bolt just keeps spinning--I don't have an inch lb. torque wrench, so I attempted to set my wrench to 9 ft. lbs. It never reached it (inaccurate below 15 as it's 5-75). I have seen a youtube of a guy using an inch lb. torque wrench and it beeped for the same job. So that plug was done by hand and no leaks once it had thread sealant.
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Old 04-25-18, 06:39 AM
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Originally Posted by Scootymad View Post
The correct torque setting is run it down with the impact. Or tighten it down until it starts to strip, then back a 1/4 turn
that was funny.....thank you for the chuckle
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Old 04-25-18, 06:50 AM
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Originally Posted by toddmorr View Post
that was funny.....thank you for the chuckle
The scary part is how much you wanna bet this happens at dealerships all the time? It's probably fine until someone wants to completely remove the plug...
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Old 04-25-18, 07:16 AM
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Those DIY spark plug change just be mindful of the clips. I've done two LS spark plug changes, the first one was no issues at all, the second one I accidentally pulled out one of the wires on the coil pack clip. It was the rear passenger side which is a little harder to reach over and pull out. The clips don't have much to grab onto so you end up trying to use the wires to pull up on and you should try your best not to do that. The wires are small in the first place and then you couple that with the age and all the heat cycles it doesn't take a whole lot to break the wires. Otherwise it's a pretty straight forward job especially if you have spark plug wrench like this.
https://www.amazon.com/gp/product/B0014ZVSVK/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 https://www.amazon.com/gp/product/B0014ZVSVK/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
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