Plugs and Coils

[TRLBOSS]

I just installed new Denso plugs and coils, 2000 LC w/197k. I've had a few aftermarket coils fail and wanted to get a complete new set of Denso's in there.

I was surprised how goo-ed up some of the plugs were (especially 6, plugs are pictured 1-8 left to right, coils are not in order). @2001LC I'd love you're opinion. I've been through both of these threads and have found them helpful:

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When to change spark plugs?

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None of them felt loose when removing, but perhaps that was because of all the goo. I'm assuming all of those taller 'hatted' coils are original. Is all that goo something I need to worry about? Is that a valve cover gasket issue, or coming up through the threads?

 

[J1000]

Oil goo looks like it's from leaking valve cover seals. The one's with browning along with their COPs may have been a little loose discolored by hot combustion chamber gas.

 

[2001LC]

Likely spark plug tube seal leak in #4, 6 & 7 tubes. I'd clean those tubes and see if it comes back in 5K or 10K miles. Never hurts to re-toque the head cover bolts to 53IN-lbf (that is inch, not pounds) while doing plugs.

Picture is too dark and wrong angle to see much of business end of plugs.

Some plugs may have been walking out. They tend to brown and as does coil boot and shaft as hot gasses enter tube. To see if Boots of coil are bad. Squeeze end, if hard and cracks open up when you do they're bad.

1st coil is dirt which may be from loose plug. Could also have not been seated/sealed properly, allowing dirt/grim in spark plug tube area. This can happens around oil fill spout from spillage.

You're missing #2 coil seal. It's likely still on engine. Get it off so you don't double seal.

 

[TRLBOSS]

Thanks. Yes, we initially double sealed, but realized it and pulled it off.

 

[kruisinkid]

Never hurts to re-toque the head cover bolts to 53IN-lbf (that is inch, not pounds foot) while doing plugs.

To be crystal clear it is 53 POUND FORCE-INCH (53 lbf-in) or 4.4 lbf-ft, which is the unit we are all used to seeing. sorry im really bored at work on a saturday night. but now i wanna go check my plugs and retorque my head cover bolts. @2001LC your thoroughness of observation never ceases to amaze me. off to amazon to finally buy a low range torque wrench.....

 

[2001LC]

Yes INCH LB. 53IN-lbf, which is ~4.4LB-lbf. I use my little 1/4" torque wrench when spec is in low range, seems more accurate. Sometimes these head cover bolts are a bit frozen up. It may take a little more torque at first to get started turning. Then they'll usually turn 1/4 to 1/2 a turn to reach 53IN-lbf. I work in a crisis cross pattern (upper than lower bolts). I then come back around for a second pass.

Every 4.7 2UZ I've re-torqued these head cover bolts on, needed at least a 1/4 turn. Seems we get shrinkage over time between the rubber washer under bolt and the rubber gasket under head cover. We've seen very good results in stopping head cover leaks doing this. I do as a PM.

For those in rust belt, good luck. These bolts can be frozen in. So go easy! They are very small bolts and can break easy.

 

[Balto1223]

To be crystal clear it is 53 POUND FORCE-INCH (53 lbf-in) or 4.4 lbf-ft, which is the unit we are all used to seeing. sorry im really bored at work on a saturday night. but now i wanna go check my plugs and retorque my head cover bolts. @2001LC your thoroughness of observation never ceases to amaze me. off to amazon to finally buy a low range torque wrench.....

Do you know the torque for the plugs, off hand?

 

[2001LC]

Toyota Factory spec is 13ft-lbf. But I've been dialing it up a bit. See Spark plugs Alert Alert Alert!

Also if the plug has been torqued once, it crushes the washer. A new plug (washer not crushed) takes about 1/2 turn pass the snug point to seat/torque. A spark plug which washer has been crushed only take about 1/8 turn pass snug to hit 13ft-lbf.

Denso has procedure on it's web page of 1/4 to 1/2 pass snug, or 18ft-lbf. Denso also states reduce torque 20% if threads are lubed. Lube like from anti-sizes or can be from oil threads.