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Going over my car this morning for a basic tune up. I decided to inspect the the spark plugs. Which in turn were replaced at a local Lexus dealer in my area. Apparently within about 500 miles ago according service history online.
To my surprise with a quick turn of the ratchet. No resistance at all from the plug. This is what I found. Checking the gap it's on par pre set to 1.1 mm gap from OEM. Mind you at .040" my spark gap tool is really 043" verified by calibrated micrometer. I'd still like to verify plug gap regardless myself, before my OCD keeps me up at night. Anyone running the Denso TT's? They perform really well too.
If you can't trust the dealer then who can you trust?
If anything like the 2GR from the ISX50. The spark plug torque spec is 18bft-lbs?
@MikeFig82 - The original equipment spark plugs factory installed in the GS 350 3.5L V6 are Denso P/N FK20HBR11. The gap on Denso P/N FK20HBR11 spark plugs is 1.1mm (.044"). The 'R11' suffix denotes 1.1mm gap as displayed in the property chart (image) below.
The quality control of Denso spark plug gaps is ± 0.001" so I would not question the accuracy of the factory preset gap - especially using a wafer-type spark plug gapper gauge.
The compression gasket (a.k.a. crush washer) on spark plugs should be crushed at 18~21 ft-lbs of torque. There should never be any anti-seize material applied to the threads of spark plugs when installing them because it prevents proper torque to be applied when tightening. Anti-seize material acts as a lubricant and can alter torque values up to 20 percent.
It's very doubtful a Lexus technician would use anti-seize material on the spark plug threads, and it's also doubtful he failed to tighten the spark plugs using a torque wrench set at the appropriate 18~21 ft-lbs. So, I cannot say why your spark plugs had less resistance than you expected when removing them.
For those DIY people replacing their spark plugs themselves or purchasing new spark plugs for someone else to replace them, be aware of fake (counterfeit) spark plugs. Buying spark plugs on eBay is not recommended, and even some Amazon partner sellers are known to sell fake (counterfeit) products. Your best source is buying from a Lexus dealership - but check to make sure they send you the correct spark plugs.
We've recently learned of one Lexus parts department that sent incorrect R8 suffix spark plugs instead of R11 suffix spark plugs that were actually needed for a 2013 GS 350 even though they supposedly checked the VIN, and unfortunately the owner didn't check behind the parts department and replaced his original equipment R11 spark plugs with the incorrect R8 spark plugs they sent him. So my advice is; don't even trust the information a Lexus parts department provides when they check VINs without doing your own research to confirm the information they provide is accurate.
If you don't care about the emission warranty or if the car is getting close to 100k miles then there is absolutely zero need or benefit (in performance or economy) in replacing the spark plugs until the car has ¼ million miles or more on it. OE Iridium spark plugs have been known to go well over 300,000 miles in Toyota/Lexus V6 engines with excellent performance and economy results.
I hope this helps you...
Last edited by bclexus; 04-29-23 at 01:08 PM.
Reason: orthography
@MikeFig82 - The original equipment spark plugs factory installed in the GS 350 3.5L V6 are Denso P/N FK20HBR11. The gap on Denso P/N FK20HBR11 spark plugs is 1.1mm (.044"). The 'R11' suffix denotes 1.1mm gap as displayed in the property chart below.
The compression washer on spark plugs should be crushed at 18 ft-lbs of torque. There should never be any anti-seize material applied to the threads of spark plugs when installing them because it prevents proper torque to be applied when tightening. Anti-seize material acts as a lubricant and can alter torque values up to 20 percent.
For those DIY people replacing their spark plugs themselves or purchasing new spark plugs for someone else to replace them, be aware of fake (counterfeit) spark plugs. Buying spark plugs on eBay is not recommended, and even some Amazon partner sellers are known to sell fake (counterfeit) products. Your best source is buying from a Lexus dealership - and check to make sure they send you the correct spark plugs.
If you don't care about the emission warranty or if the car is getting close to 100k miles then there is absolutely zero need or benefit (in performance or economy) in replacing the spark plugs until the car has ¼ million miles or more on it.
I hope this helps you...
Yeah at this point the washer is crushed. I just turned the ratchet about 1/16" at full stop. 18 ft lbs is no longer viable to me. Worse case scenario I'll get a new set. It's a shame since these a new set. I'll monitor the butt dyno in the coming week. Also yes I agree the tech should know better. The 10mm bolts on the ignition coils put up a better fight.
Yeah at this point the washer is crushed. I just turned the ratchet about 1/16" at full stop. 18 ft lbs is no longer viable to me. Worse case scenario I'll get a new set. It's a shame since these a new set. I'll monitor the butt dyno in the coming week. Also yes I agree the tech should know better. The 10mm bolts on the ignition coils put up a better fight.
Thanks again.
You should just put those back in with using a torque wrench.
18-21 ft lbs is not a lot and probably why you felt they were too loose or not tight enough.
You should just put those back in with using a torque wrench.
18-21 ft lbs is not a lot and probably why you felt they were too loose or not tight enough.
Here's the driver's side a little better torqued. I'm not saying they felt loose. They're loose I basically turned them by hand. The 10mm coil bolts were tighter.
I'm going to be reusing. I just picked this car up last Friday.
Here's the driver's side a little better torqued. I'm not saying they felt loose. They're looseI basically turned them by hand. The 10mm coil bolts were tighter.
I'm going to be reusing. I just picked this car up last Friday.
@MikeFig82 - If a spark plug's gasket (a.k.a. crush washer) is compressed there is absolutely no way (it is literally impossible) to break the created tension that would allow you to turn the spark plug by hand. Even without a gasket (i.e. crush waster) when you bind a threaded metal part against another metal part there is a tension created in the pitched threads as well as against the two parts that tightly binds and secures them...
As for re-installing spark plugs - if the gaskets (i.e. crush washers) are crushed I suggest installing them with a few extra ft-lbs more torque.
The chart (image) below is Denso's Recommended Installation Torque Specifications. The FK20HBR11 spark plug is a M14 Thread Size that takes 20-25 Nm recommended torque or 15-18 ft-lbs.
You'll note in the specification chart (image) below that when installing a new spark plug the recommended turns - a.k.a.'turn angle' - after lightly tightening the plug by hand or by using a spark plug wrench is ± ½ turn. And for installing a used spark plug it is only 1/12 turn, because on a used spark plug the crush washer has already been flattened (compressed/crushed). I personally suggest installing used plugs with a few extra ft-lbs more torque.
Denso states when installing new spark plugs to lightly tighten it by hand or by using a spark plug wrench before applying the ± ½ turn angle that a torque wrench set at the recommended torque value will turn the plug.
Once the torque wench clicks-off and releases, the preset torque value has been successfully reached, however it is standard practice among experienced mechanics, and recommended, to repeat the tightening process to confirm the desired torque value has successfully been achieved.
Last edited by bclexus; 04-29-23 at 10:34 AM.
Reason: orthography
@MikeFig82 - If a spark plug's gasket (a.k.a. crush washer) is compressed there is absolutely no way (it is literally impossible) to break the created tension that would allow you to turn the spark plug by hand. Even without a gasket (i.e. crush waster) when you bind a threaded metal part against another metal part there is a tension created in the pitched threads as well as against the two parts that tightly binds and secures them...
As for re-installing spark plugs - if the gaskets (i.e. crush washers) are crushed I suggest installing them with a few extra ft-lbs more torque than 18~21 ft-lbs.
Well you get my drift maybe not . It took no effort for passenger side plugs. The combustion gasses (Maybe incomplete) had already started pooling on the lower spark plug well. The driver's side were a lot better. No liquid residue. Thank goodness no leaking valve covers. Other than that this engine is solid.
This is what I'm used to seeing on a 60k interval plug swap near completely dry threads.
At this point what's done is done. I was just checking the plugs on the vehicle since it's sitting at 110k the only major service performed was the plugs change. Also the differential fluid around 75k. It looks like they serviced it regularly up until they traded it in at a non Lexus dealer.
This is what I'm used to seeing on a 60k interval plug swap near completely dry threads.
Near completely dry threads on used spark plugs is a preconception that is rare.
Some oil on the threads is far more typical.
These OE spark plugs (pictured below) had over 146k miles on them, which may not be representative of spark plugs with say 60k miles on them, but most spark plugs do indeed have oil in the threads.
Last edited by bclexus; 04-29-23 at 10:05 AM.
Reason: orthography
I decided to inspect the spark plugs Which were replaced at a local Lexus dealer in my area about 500 miles ago according service history online.
It looks like those almost new spark plugs that replaced the OE spark plugs just 500 miles ago (seemingly to have been properly torqued by the compressed crush washers) have oil in their threads, which is very typical and to be expected.
Gasket
Makes the housing and the engine fit tightly to each other and maintains the airtightness of the combustion chamber.
There is a procedure for tightening and the appropriate tightening margin must be secured.
For details, refer to the information in “SPARK PLUG Installation”.
Last edited by bclexus; 04-29-23 at 11:01 AM.
Reason: orthography
I think OP was doing it more to demonstrate on the replaced plugs, but I don't think that style measuring tool should be used to measure gap on iridium plugs. Something about it causing damage by scraping the metal. The feeler style is preferable, assuming you're going to measure. Unless it's obviously damaged, I usually don't measure a plug, but maybe I'm more trusting.
If you don't care about the emission warranty or if the car is getting close to 100k miles then there is absolutely zero need or benefit (in performance or economy) in replacing the spark plugs at the recommended 60k mile maintenance schedule. In fact, Iridium spark plugs will last and perform like new until the car has ¼ million miles or more on it. Original Equipment Denso Iridium spark plugs have been known to go well over 300,000 miles in Toyota/Lexus V6 engines with excellent performance and economy results.
__________________
Don't just take my word for it - that you're wasting both time and money replacing the OE Denso Iridium spark plugs at 60k miles. Take the word straight from Denso that their Iridium spark plugs will last beyond 100,000 miles. Is there any question why Lexus only trusts Denso spark plugs as original equipment in their vehicles?
I would simply clean the threads, reinstall and properly torque them. I use just a tiny wisp of antisieze on the threads and torque to the lower range. A decent torque wrench is a great tool to own. I have a Snap On flex head...
It is odd that they were so loose. Plugs tend to tighten up over time. I've never seen loose plugs. Never. Those plugs appear have way more than 500 miles on them.
If you have any question, I would consider swapping them out. Then you can forget about it for a loooong time.
If you don't care about the emission warranty or if the car is getting close to 100k miles then there is absolutely zero need or benefit (in performance or economy) in replacing the spark plugs at the recommended 60k mile maintenance schedule. In fact, Iridium spark plugs will last and perform like new until the car has ¼ million miles or more on it. Original Equipment Denso Iridium spark plugs have been known to go well over 300,000 miles in Toyota/Lexus V6 engines with excellent performance and economy results.
__________________
Don't just take my word for it - that you're wasting both time and money replacing the OE Denso Iridium spark plugs at 60k miles. Take the word straight from Denso that their Iridium spark plugs will last beyond 100,000 miles. Is there any question why Lexus only trusts Denso spark plugs as original equipment in their vehicles?
I'm not questioning you. I belive it thats why I'm here hoping that one day I'm able to get my hands on a GS-F even it's old by then. You can't beat the reliability ever of Toyota. I have friends at work always saying don't buy a BMW. I think deep down they wish they got something a little more reliable.
Also I just read a member on here he's on 200k miles on OEM plugs.
I would simply clean the threads, reinstall and properly torque them. I use just a tiny wisp of antisieze on the threads and torque to the lower range. A decent torque wrench is a great tool to own. I have a Snap On flex head...
It is odd that they were so loose. Plugs tend to tighten up over time. I've never seen loose plugs. Never. Those plugs appear have way more than 500 miles on them.
If you have any question, I would consider swapping them out. Then you can forget about it for a loooong time.
Yes sir thats what I did. Just cleaned them slapped them back. Yeah, I picked up some torque wrenches awhile back CDI brand something like that 1/4, 3/8, 1/2 sizes. I do maybe need to get them recalibrated. I've never looked into it since I got them.
I would simply clean the threads, reinstall and properly torque them. I use just a tiny wisp of antisieze on the threads and torque to the lower range.
@JeffKeryk - Denso states: CautionDo not apply screw thread lubricant to the spark plug...
Last edited by bclexus; 04-30-23 at 06:44 AM.
Reason: orthography
04-29-23, 05:20 AM
Under-Torqued Spark Plugs
. It took no effort for passenger side plugs. The combustion gasses (Maybe incomplete) had already started pooling on the lower spark plug well. The driver's side were a lot better. No liquid residue. Thank goodness no leaking valve covers. Other than that this engine is solid. 
Makes the housing and the engine fit tightly to each other and maintains the airtightness of the combustion chamber.
