Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!

[2001LC]

@2001LC, thanks for this thread and your details, ( on all your threads) on spark plugs. How does everyone think these plugs look, from experience? Comments please? From what I can tell, no idea when changed in past. 60k to 250k, shows no plug swap. Truck seems to run more peppy with new OEM plugs but never exhibited an issue when driving / on long road trips.

Order of plugs has nothing to do with engine location.

Plugs appear to be from Japan, which most times those are factory installed. I've not purchase from Toyota in years. I suppose it possible; Toyota (Dealership parts dep) may sell Denso from Japan IDK. Today all Denso spark plugs I buy (parts store and online) are assembled in USA with foreign parts.

Your plugs appear to be firing fine. The two with brown staining, were likely leaking hot gasses from threads (loose spark plugs) during cold start up, tightening after warm up. They likely drew more current as not ground as well. The COP boots on those two, are likely stiff and could use refreshing.

The key whether they are reusable is gap. Those start at 1.1mm gap. Once they reach 1.3mm they should not be used. Wide gap results in more power draw from COP (coil on plug). This create more heat in COP. Heat is what degrades the COPs.

 

[blatant]

Plugs appear to be from Japan, which most times those are factory installed. I've not purchase from Toyota in years. I suppose it possible; Toyota (Dealership parts dep) may sell Denso from Japan IDK. Today all Denso spark plugs I buy (parts store and online) are assembled in USA with foreign parts.

Your plus appear to be firing fine. The two with brown staining, were likely leaking hot gasses from threads (loose spark plugs) during cold start up, tightening after warm up. They likely drew more current as not ground as well. The COP boots on those two, are likely stiff and could use refreshing.

The key whether they are reusable is gap. Those start at 1.1mm gap. Once they reach 1.3mm they should not be used. Wide gap results in more power draw from COP (coil on plug). This create more heat in COP. Heat is what degrades the COPs.

Thanks! Nice to know. The new plugs are all Toyota but didn't see collar stamp but you are most likely correct. Appreciate the eye look.

 

[AlpineAccess]

The picture below is not mine, but a recent post from Reddit. This is a yota 4.7.

Check your plugs. I am adding this to my 30k maintenance.

When I did valve cover gaskets I checked all of mine and found two loose. They had been replaced 50k earlier. Two coil pack failures and both coil packs had failed on cylinders with improper spark plug torque. One was finger tight.

 

[2001LC]

Some of you may have seen my thread, in which I worked on a locals rig. Inspecting a 100 series for "LEAKS" "Yeaks"
It had about $15k of work done (by three different shop) recently to base-line plus inspect. Very nice and clean 05LX w/147K miles from TX. Yet not one of those shops found the over 1/2 dozen issue reducing reliability, that would cause damage and expensive repairs. Some of issues they/shops created, typical of what I see. The two most pressing which would have disable the rig on side of the road. Cracked radiator top and loose plugs.
#3 plugs was so loose it was not sealing at operating temp. This would have blown out of the head, likely within 5 hours of a 20 plus hour road trip planned for July.

Notice how black & dry coil boot and plug of #3 cylinder is. That happens when gasses escape during engine running, after engine at operating temp. Others brown and oily would have been loose, but just during cold start up, then tighten with heat expansion. These where also are platinum plugs, I'd never use any not iridium.
Head cover gasket had been replaced. But those bolts where loose as i recall, some ready to fall out. But no spark plug tube oil seal leaks. All oil on plugs and coils, is from combustion cambers gasses escaping.

 

[2001LC]

One think I'm now thinking is:

Perhaps not a bad idea to use Lexus PM schedule and change spark plugs at 60K.

I say this, not due to plugs being bad, but because the crush washer is best on first torque in.

 

[blatant]

Toyota (Dealership parts dep) may sell Denso from Japan IDK. Today all Denso spark plugs I buy (parts store and online) are assembled in USA with foreign parts.

You Sir are correct, just looked at the box the new plugs came in and it says "Toyota Motor Sales, made in the USA with foreign content."
SK20R11.

 

[2001LC]

You Sir are correct, just looked at the box the new plugs came in and it says "Toyota Motor Sales, made in the USA with foreign content."
SK20R11.

I wasn't sure if the Toyota sold plugs where USA also.

I just R&R a set in 01LX w/264K miles (Whitlady) while doing a tune for her owner. The gap had grown to 1.3mm, as such not reusable. They where factory's from Japan with 264K miles. I'd re-torque then a few times over the years.

 

[NoTempoLimit]

How long can the plugs be reasonably expected to stay tight when they are torqued to the recommended 17.5 N•m (13 lb-ft)?

I had planned to pull one plug on my LC to see if the plugs had been changed as the P.O. claimed (they had) and then I remembered this thread and torqued all 8 (all seemed at least a bit loose). But with the sun blasting on me in the near-desert of the San Fernando Valley in June, I did not think to consider if the torque should be increased.

I have a 2000 mile road trip ahead of me and no time to deal with the plugs again before departing. I assume I should be OK with recently torqued plugs even at the recommended torque value.

Is there any agreement on an increased torque value? I have a high quality certified torque wrench so I know I can accurately reach a torque value.

 

[2001LC]

~30K miles @ 13ft-lbf from factory. ~30 to 50K @ 18ft-lbf.

 

[apdxyk]

You need to re-calculate the torque number if you put any lubricant on the threads.

 

[2001LC]

Denso gives use various tightening method, allowing up to 18ft.lbf and states reduce torque 20% when threads lubed.

 

[dace voit]

Denso shows the 14mm flat seat plug having a torque range of 15-22 ft/lb. I chose 18 ft/lb to be just shy of the middle. These heads can probably take 22 ft/lb but I don't want to go that high if Toyota recommends 13 ft/lb.

 

[2001LC]

I stand corrected, my recollection was 18ft-lbf as is max I'm currently using also. I'll post the link to Denso again. It's the 14mm plugs

Spark Plug Installation

Spark Plug Installation

densoautoparts.com

 

[2001LC]

A few last minutes teaks for Merlot before delivery and heading on road trip and to HIH..

From post in Merlot:
I had a new set of Denso TT spark plugs on the shelve. About and hour before I planed to head to airport I decided to install them. You may recall earlier in the thread, I inspected and re-torque them to 18ft-lbf. But something I've been considering just recently, is that the crush washer having been crushed will not seal as well as new. So to this end, I elected to replace all 8 spark plugs with the new .4mm Denso TT's I had. Scored 2007 LC W/63K No AHC Clean. Adding Lift, Sliders & skids!

 

[2001LC]

I've now founds one ready to blow out head. This is a serous issues that can get very expensive. Although 30K re-torque may be to aggressive, 60K is a must. But really feel how many warm ups and cooling cycles is the key. Those driving short tips daily would use more aggressive timing.

One more thing I've found. Re-torque not as effective as just replacing the plugs. The crush washer does not do a very good job at sealing the second time (once crushed). Whereas the risk of blow-out is mitigated, will still get some leakage unless plug replaced to get that new crush washer.

I tested this with Merlot (07LC 64K miles) After re-torquing all plugs. I drove 1k miles and pulled the plugs. I noted some oil leakage at crush washer. So I replaced.

Side Note: I used the TT's and reset ECM by disconnect battery on Merlot. Topped off the gas tank and drove 3 miles to get on HWY. Shut engine off at each red light, to speed up ECM learning. Saw mid 17 MPG on HWY to Airport with 33" tire. Which means MPG was in 18s if I'm thinking correctly. WOW! Could the TT have made difference.

 

[MountaineerLC]

I'd noticed a tick that I initially chalked up to a manifold leak. Over the last few month it's became more consistent and stopped going away as the engine warmed up. After discovering this thread, I figured checking the plugs would be advisable. Good thing I did. All were loose and a few were just hand tight. Fortunately, I caught before any damage was done. I cleaned and re-torqued them to 15ft-lbs. Pic below of the worst one. The tick is now gone.

 

[2001LC]

You must have wiped that one coil off. I say that because when I see so loose gasses blow by threads after warm up. Then the coils usually have a great deal of blow by carbon on them.

 

[boobird]

I recently replaced the plugs and now have a gas smell in the cabin.

Should I have replaced the boots and gaskets?

 

[AlpineAccess]

I recently replaced the plugs and now have a gas smell in the cabin.

Should I have replaced the boots and gaskets?

More likely that in moving something around to access the spark plugs you created a gas leak. Check around your injectors and fuel rails for leaking, and do it sooner than later. It's not hard to bump something and there are plenty of lines there that can be old/brittle.

If the spark plugs are tight, the boots and gaskets on coil packs don't matter. Even if the plugs are loose its unlikely you would smell gas. If you were, the plug would have to be so loose and the vehicle running so rich that the smell would be followed by a plug being ejected and much bigger issues at hand.

 

[Pyrenees]

More likely that in moving something around to access the spark plugs you created a gas leak. Check around your injectors and fuel rails for leaking, and do it sooner than later. It's not hard to bump something and there are plenty of lines there that can be old/brittle.

If the spark plugs are tight, the boots and gaskets on coil packs don't matter. Even if the plugs are loose its unlikely you would smell gas. If you were, the plug would have to be so loose and the vehicle running so reach that the smell would be followed by a plug being ejected and much bigger issues at hand.

This is sound advice.