Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert! (4 Viewers)

[2001LC]

I did a compression check 6 mo. ago and tightened all the plugs to spec. Had an ignition coil fail last week, replaced it, and saw that the spark plug appeared to be under-tightened (not the cause of the coil failure - that was due to age).

Today, I checked all 8, and 3 more were more-or-less finger tight. I tightened all to spec (and a little bit more). I heard no ticking sound, but clearly 4 of my 8 plugs were somewhat loose. Worth checking this from time to time.

That's very unusual, for only six months.
Which make spark plug?
Was this engine, cold started two or more times each day?
What torque did you use, after compression test?

I seen a few, where plugs were not actually torque down. I can only make this call, if crush washer not crushed.

FWIW: I do all assemblies with torque wrench. I paint every nut & bolt after torqued. But with plugs, I've not been painting. I toque each, after snugging before moving to next plug. I may, change that up. To painting a mark at top of spark plug tube. Then, distraction will not result in a no torque.

 

[SteveH]

@dace voit and @2001LC - the plugs were the correct Denso or NGK from a dealer (they came with the truck, so I don't recall for sure). The truck is a DD, so it's started and driven frequently. The plugs have a small amount of anti-seize on them, which may be the smoking gun here. This time, I torqued each plug to 18-20 lb-ft. I'm getting, er, old, so I'm trying to be more methodical in how I do this, and how I document the work. I guess I'll check the plugs in another 6 months.

 

[2001LC]

@dace voit and @2001LC - the plugs were the correct Denso or NGK from a dealer (they came with the truck, so I don't recall for sure). The truck is a DD, so it's started and driven frequently. The plugs have a small amount of anti-seize on them, which may be the smoking gun here. This time, I torqued each plug to 18-20 lb-ft. I'm getting, er, old, so I'm trying to be more methodical in how I do this, and how I document the work. I guess I'll check the plugs in another 6 months.

"This time". So assume did not torque first time, may have been the issue. I've tested both reused and new torqued to 18ft-lbf, at 30K. Still sung!

Warning. If the plugs with anti-seize grease loosen. The combustion gasses escaping, can combine grease in the threads. This if aloud to go on, cooking the combine mix. Results in threads getting locked into the head. Real PITA to get them out if it happens.

 

[Wildcat Walker]

Im not sure about anti seize cooking and seizing the threads, but I do know that you need to reduce your specified preload when using it. Also, NGK does not recommend using anti seize as it is an insulator and can degrade the grounding performance of the plug. Ideally you're changing plugs every 100k or so and they aren't in long enough to become an issue. Things rarely turn out ideal so I settle for the middle ground with a very small amount of copper anti seize.

 

[medtro]

I did a compression check 6 mo. ago and tightened all the plugs to spec. Had an ignition coil fail last week, replaced it, and saw that the spark plug appeared to be under-tightened (not the cause of the coil failure - that was due to age).

Today, I checked all 8, and 3 more were more-or-less finger tight. I tightened all to spec (and a little bit more). I heard no ticking sound, but clearly 4 of my 8 plugs were somewhat loose. Worth checking this from time to time.

I had similar experience, the only time my spark plugs got loose was after they were torqued to 18 ft-lb. They were loose in less than 12 months.

 

[94SRUNNER]

I had similar experience, the only time my spark plugs got loose was after they were torqued to 18 ft-lb. They were loose in less than 12 months.

Your plugs came loose after you torqued to 18ft-lb?

 

[medtro]

Your plugs came loose after you torqued to 18ft-lb?

Yes

 

[dace voit]

Yes

Interesting data point. This is the first I've read on 18 ft/lb coming loose. New plugs or a retorque?

 

[medtro]

Interesting data point. This is the first I've read on 18 ft/lb coming loose. New plugs or a retorque?

New plugs.

 

[dace voit]

New plugs.

Thanks.

 

[bcsteel]

I just changed mine. 6 of 8 were hand tight. Had no tick yet. To note. I have no idea how old they were. So if you have not baselined your truck. Do so…

 

[94SRUNNER]

Yes

That is very interesting. Anti-seize added?

I have been checking torque on my plugs for the last 2-3 years every 6-12 months. I've never found them to be out of spec. Torque has been 17-18ft-lbs

 

[medtro]

That is very interesting. Anti-seize added?

I have been checking torque on my plugs for the last 2-3 years every 6-12 months. I've never found them to be out of spec. Torque has been 17-18ft-lbs

No anti-seize or any lubricant used.

 

[MechE30]

Checked mine today, glad I did. Four were able to be turned without a wrench. Lots of blow-by deposits going on. Cleaned the threads of the plugs with a wire brush and torqued to 18ftlbs.

 

[dahlmaker]

According to Time Sert, here is the correct Time Sert for the Land Cruiser 100. I had ordered the wrong one from Amazon.

Time-Sert 4412E-111 M14 x 1.25 Deep Hole Metric Spark Plug Thread Repair Kit - https://www.mechanicstoolsandbits.com/time-sert-4412e-111-m14-x-1-25-deep-hole-metric-spark-plug-thread-repair-kit?search=4412E-111

Update - Got the Time Sert in without much difficult. It was a bit tricky to figure out the depth, but otherwise straightforward. The sparkplug screwed right in. The plug next to it was seized though and a few pieces of ceramic broke off, so that one took some time to work out, but eventually loosened up after a night sitting in PB.

She's purring now...Time to do the other side.

 

[jazzcat90s]

Had some ticking in my new to me 03 uzj100
Changed all 8 plugs and coils , pass side cylinder head was the worst with the plugs only finger tight. Ticking went away torques to 18ft lbs will check in a couple months to see if they back out.

 

[Bisho]

Baselining my 2007 LX. Carfax showed new plugs 20k miles ago. They were original coils and newer NGKs with like new gap, but all were finger tight. #5 was a little harder to back out and actually appeared to have heat damage and what looks like burn marks on one side of the coil. It does appear to have a good seating surface on the head, so a bit baffling. I cleaned up the plug and swapped the coil with a spare, and I’ll recheck it in 5k miles. Engine ran smooth as silk and no abnormal noises.

 

[flyingscot]

Wonder if plugs were put in ‘dry’ or lubed? Supposed to be dry…..

 

[Bisho]

Wonder if plugs were put in ‘dry’ or lubed? Supposed to be dry…..

They were dry, no signs of anti seize

 

[Rednexus]

Checked them in my 2007 GX470 today (176K on the rig, probably ~40-45K on the plugs which were Densos). Sure enough, every single one of them was loose. I didn't check the initial torque but am thinking it was in the ~5-10 ft/lb range. I set all of them to 15 ft/lbs which required around 1/2 to 3/4 of a turn for each of them. I don't think whoever installed them before (probably the Toyota dealer who did a T-belt at 135K before I bought it) used anti-seize, so I'll chalk this up to them just getting loose with time. I'll check them every ~30K in future, probably when I change the transmission fluid.

Zero ticking before and after. I have LT headers so no exhaust ticks. It was well worth the 20-30 minutes to check them. My OEM Denso coil packs were also all in great shape (no cracking or other signs of degradation).