NGK Ruthenium spark plugs after 80k miles

[Deontologist]

How do these look?

I think the tube seals and valve cover gasket in general is leaking...right? Started seeing oil seep out from the valve cover and cake up in the engine bay. There seems to be oil caked on the spark plugs ... not sure what else that it could be.

 

[B1974]

If it's a plastic valve cover I'd buy a new one that comes with a gasket and new tube seals installed. I changed the seals and gasket on my ecoboost only to have the valve cover crack 18 months later.

 

[TomYoung]

Were these OEM? You have a little bit of oil on the second plug from the left, maybe some evidence of some socket manhandling on the way in and/or out and very obvious indications of high temperatures. From afar, it looks like you have large gaps, but that is a guess. I think that changing them is in order. What is the application?

On your question, I would replace the valve cover gasket and tube seals, along with the plugs and see where you are.

 

[dubber09]

How much oil did you see in plug wells? Porcelain is suspiciously way too dirty on the second plug and very clean on last one. Also, I think plugs may have not been tightened right on install, crush washers look 'not flattened'.

 

[Deontologist]

Were these OEM? You have a little bit of oil on the second plug from the left, maybe some evidence of some socket manhandling on the way in and/or out and very obvious indications of high temperatures. From afar, it looks like you have large gaps, but that is a guess. I think that changing them is in order. What is the application?

On your question, I would replace the valve cover gasket and tube seals, along with the plugs and see where you are.

Not OEM

Application 2018 RAV4 2.5l 2ar

Installed at about 90k miles

I tightened them by hand until finger tight, then did the NGK recommended 1/2 turn to 2/3 turn. I just did 1/2 turn instead of going up to 2/3 turn.

 

[TomYoung]

Not OEM

Application 2018 RAV4 2.5l 2ar

Installed at about 90k miles

I tightened them by hand until finger tight, then did the NGK recommended 1/2 turn to 2/3 turn. I just did 1/2 turn instead of going up to 2/3 turn.

Interesting. Maybe go back to OEM plugs?

 

[Deontologist]

Interesting. Maybe go back to OEM plugs?

What do you think caused the high temperatures? If it matters, the coils were stained brown, presumably from engine oil. Could it have been the oil seeping in past the tube seals causing the high temps? Or could it have been undertorquing them? Regrettably, I did not use a torque wrench, but from what I understand the NGK 1/2-2/3 turn after finger tight is a trustworthy recommendation at getting to about the same level of preload, possibly even better than torque alone, as angle ignores factors like thread friction, etc. I mean, aren't critical fasteners like head bolts torqued with an angle spec?

 

[Number_35]

The precious-metal electrodes are still present and well-defined. I'd say they've held up well for the mileage on them.

 

[jayjr1105]

I have these in my Mazda. Only about 35K on them. Not even going to glance at them until 100K

 

[researcher]

What do you think caused the high temperatures? If it matters, the coils were stained brown, presumably from engine oil. Could it have been the oil seeping in past the tube seals causing the high temps? Or could it have been undertorquing them? Regrettably, I did not use a torque wrench, but from what I understand the NGK 1/2-2/3 turn after finger tight is a trustworthy recommendation at getting to about the same level of preload, possibly even better than torque alone, as angle ignores factors like thread friction, etc. I mean, aren't critical fasteners like head bolts torqued with an angle spec?

I usually slowly tighten them by hand (with the extension and spark plug socket) until it stops. Attach the ratcheting wrench starting at the 12-oclock position and tighten it to about the 8-9 oclock position. Which is about 2/3 turn. But wait.. I re-read what you did, only 1/2 turn not 2/3. Could you not turn anymore than 1/2??

Another thing to think about is the spark plug threads in the cylinder head. There are thread chasers that can clean up the threads (you add grease to the valleys of the chaser to catch the carbon). The carbon in the threads can give you a false sense that the plug is fully tightened. Maybe that's why you could only turn 1/2..

If the main valve cover gasket is leaking, would make sense the tube seals might too. Did you see oil down in the tube before you took the plugs out? I didn't see if you mentioned that..

And are they the correct heat range? NGK does have a conversion chart to make sure you get the correct heat range.. I've seen odd things when the plug is too hot of a heat range.

 

[Deontologist]

I could have gone more than 1/2 turn but I chose not to, I wanted to just be on the safe side rather than overtorque the plugs and strip out the threads.

I didn't see any liquid oil when I took out the plugs, but, the plug boots were stained brown, I'm guessing from oil. And I'm guessing that black stuff caked on some of the plugs is dried oil.

As far as whether the plugs are the correct heat range, no idea. I just used RockAuto to buy the plugs. RockAuto said the plugs were compatible and that's about all I know. I mean, I physically compared the size of them with the original OEM plugs and they looked identical, but I didn't really look into compatibility any more.

 

[Hall]

Does the "dirty" threads really mean anything ? I thought what really matters is the electrodes. Same with the ugliness on the porcelain - that's mostly cosmetic, isn't it ?

 

[kschachn]

Yes leaking tube seals on at least three out of the four cylinders. You don’t always find liquid oil in the well. As mentioned does it matter? Well maybe not at this point but it isn’t going to get any better over the next 90k.

 

[researcher]

I could have gone more than 1/2 turn but I chose not to, I wanted to just be on the safe side rather than overtorque the plugs and strip out the threads.

I didn't see any liquid oil when I took out the plugs, but, the plug boots were stained brown, I'm guessing from oil. And I'm guessing that black stuff caked on some of the plugs is dried oil.

As far as whether the plugs are the correct heat range, no idea. I just used RockAuto to buy the plugs. RockAuto said the plugs were compatible and that's about all I know. I mean, I physically compared the size of them with the original OEM plugs and they looked identical, but I didn't really look into compatibility any more.

I hear ya, the last thing you want is to keep tightening then you hear POP and there goes the threads in the cylinder head!! One of the worst sounds while working on a car..

I agree that looks like the valve cover gasket and the spark plug tube seals needs to be replaced, as you probably already guessed correct. Yeah the heat range is the number on the spark plug part number, NGK has a chart that can decipher that, but RA is probably correct.

So all that leaves is contamination from valve cover gasket that includes the spark plug tube seals. Replace the plugs, gasket, see how it goes from there. I know, simple, right? lol

 

[Chris142]

The 2nd one is allowing exhaust gasses up between the ceramic and the metal .

 

[slacktide_bitog]

Oil on the spark plugs means you have a leak and need a valve cover gasket and spark plug tube seals. The Mahle valve cover gasket includes the tube seals.

Do you know the torque spec? Find out the torque spec and use a torque wrench,. Harbor Freight has a good 3/8 torque wrench at a fair price

 

[Deontologist]

Oil on the spark plugs means you have a leak and need a valve cover gasket and spark plug tube seals. The Mahle valve cover gasket includes the tube seals.

Do you know the torque spec? Find out the torque spec and use a torque wrench,. Harbor Freight has a good 3/8 torque wrench at a fair price

Yes, I think it's either 13 or 18 ft lbs. I have a nice Tekton beam style 3/8" torque wrench I use for my lug nuts, but, it only goes down to 20 ft lbs. I would like to get another beam style wrench. I hate the twist-handle torque wrenches that need to be set to 0 after each use. Too bad I can't seem to find a Tekton 3/8" that goes down into the low torque range ... maybe I'll just get a 1/4" and use a 3/8" adapter or something.

I just checked my Chilton manual and it says 18 ft lbs, some online forums have said they have seen 13 ft lbs.

I may try to buy a torque wrench and re-check the plugs to see if they're 18 ft lbs or close. If I do buy a torque wrench it will be a high-quality split-beam or digital unit.

I may also try to crack open the spark plug threads and spray some lubricant like PB Blaster or maybe Seafoam into the hole to clean up the carbon from the threads. Chasing the threads with a thread chaser is not something I'm comfortable with, however.

 

[slacktide_bitog]

Yes, I think it's either 13 or 18 ft lbs. I have a nice Tekton beam style 3/8" torque wrench I use for my lug nuts, but, it only goes down to 20 ft lbs. I would like to get another beam style wrench. I hate the twist-handle torque wrenches that need to be set to 0 after each use. Too bad I can't seem to find a Tekton 3/8" that goes down into the low torque range ... maybe I'll just get a 1/4" and use a 3/8" adapter or something.

I just checked my Chilton manual and it says 18 ft lbs, some online forums have said they have seen 13 ft lbs.

I may try to buy a torque wrench and re-check the plugs to see if they're 18 ft lbs or close. If I do buy a torque wrench it will be a high-quality split-beam or digital unit.

I may also try to crack open the spark plug threads and spray some lubricant like PB Blaster or maybe Seafoam into the hole to clean up the carbon from the threads. Chasing the threads with a thread chaser is not something I'm comfortable with, however.
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The twist handle torque wrenches aren't supposed to be set to 0 after each use. They're supposed to be set to the lowest torque value supported.

For example, the HF 3/8 torque wrench goes from 5-80 lb ft. You set it to 5 when you're done.

 

[kschachn]

I've given up on using a torque value for spark plugs. There are just too many variables to make that a method I'm confident in using. As noted already in this thread the box generally gives a torque angle specification, using that eliminates the issues I have with a torque value.

 

[lbhsbz]

Does the "dirty" threads really mean anything ? I thought what really matters is the electrodes. Same with the ugliness on the porcelain - that's mostly cosmetic, isn't it ?

Yes, it means they were loose.

Those threads are about an inch long....M14 (at least)...I don't see how you could strip those. Tighten until the washer is crushed and it stops turning to put some thread tension on 'em.