icerunner

This time it came true

About 35K miles ago I swapped out my spark plugs on my 99' 3.4L (w/ denso duel electrodes) and I thought I was trying to be extra careful NOT to strip out the threads of the plugs so I took it easy torque them down (about 12-14 foot pounds torque)...Well at 165,000 miles I started to hear predetonation or pinging sound under hard acceleraion coming from the passenger side of the engine. This freaked me out some what and well soon after I decided to check the plugs so during the swap out and inspection of the Spark plugs I discovered the culprit one Plug for the the middle cylinder on the passenger side of the engine (under the air intake duct) was Very loose.... YIKES!! I also immediatly noticed that the plug was so loose that the cumbustion gasses were coming out of the socket as it turned the grey plastic spark plug shaft brown and the head was slightly discolored in this area as well... also I found a small amount of shinny metal flakes on the plug shaft and on the piston top upon removal... this was posssibly the spark plug threads (on the head) partially damaged due to the loose plug...Again Yikes... !! So I took out the old plugs LIGHTLY coated the new plug threads (this time) with anti sieze and torqued them down slightly tighter this time...Started it up and thank god every thing still runs great...

Other notes:
1)THe older plugs with 35K miles stilll looked ok (slight wear) yet I replaced them anyway with new densos
2) I increased the torque to about 15 -16 foot pounds untill I was sure they were tight enough
3) THIS time I went real light on the anti seize compound as I may has used too much on the last plug change out...
4) After Inspecting the older plugs I noted that the plug gasket on the older plugs was not compressed at all (my bad). Therefore I guess I did not torque them enough previously. Again yikes, I could have striped the threads on that one cylinder IF I didnt check the plugs when I did...

akaphilly

glad it all worked out. i am about to replace my plugs.. can anyone comfirm the 15-16 foot pounds? i'll check the fsm later

Godzilla

FSM calls for 13. I never/or would go tigher than that.

Elton

hmm i dont have a problem not going cheap on the anti seize i probably use to much .i just go by feel when they get tight i go just a little turn more never had a problem yet

algranger

Huh... i've never torqued my spark plugs, i just make them "tight"

Hope this next set works out for ya

dannomite

Often there is a torque on the spark plug package itself. I check that number against the spec in the book and if there is a difference I go with the service manual.

cackalak han

Not trying to recommend this to anyone, but over the many spark plug changes, I have never used a torque wrench. The plugs already have those crush washers. I just get it tight (hand), then turn maybe another 1/2 to 1 turn. Never had one come loose on me. Nice and firm, but not crazy tight.

Oh, yeah, definitely put some anti-seize on the threads. Helps to get the correct torque, if you're doing it that way.

Elton

ive never used a torque wrench i go by feel if its something like major engine parts ill use one

yamagirl

Ooops...I bought my prerunner new in 00 and did the plugs at 90K with a T belt and w pump,its now on 185K and time for another belt etc. Had hubby do the plugs himself ths time to save a few bucks and the old ones looked really good still. I never had a loss of mileage of missing etc and now think why love it to death or if it aint broke dont fix it till it is,. still find it odd at how much faster and more powerful the truck is than the 98 4 runner,must be the weight difference.