0 Members and 4 Guests are viewing this topic.
.. I am thinking they over tightened them and damaged the insulators.
is it possible that it is rust and not burn marks?
I think that residue in not uncommon on spark plugs. How many miles on them?Gnarls.
. I am thinking they over tightened them and damaged the insulators.
The Denso iridium for a 4.7 could be 19mm thread depth, which specs at 28 to 34 ft. lbs. of torque without lube.. that's a lot!Those don't look like 19mm. If they are 14mm - they spec at 7 to 15 ft lbs.Gnarls.
That pattern is definitely due to electrical arcing. Are you sure it wasn't the wires arcing to the plug across the ceramic portion?
Gnarly4X, I agree the plugs were likely damaged and caused the problem.Karen says there was slow/sluggish throttle response till I changed the plugs yesterday.I put Dielectric grease in the boot as well, and the Anti-seize I use is made with copper and has great conductivity. If you brush a three inch long smudge across a piece of glass or plastic it still shows no resistance. Do the same thing with a pencil ( pencils use graphite) you will have a resistor.
IIf the dealer was the last to touch the plugs, and did the dirty deed of over-torquing, it's a typical reason why some of us, myself included, have had a bad experience with the "expert" dealer technicians. A good friend of mine is an ASE Certified auto tech and quit a dealership because they wanted "speed fixes" and not the quality repair work and the right way, he believed should be done. He said basically the dealership was screwing its customers with less than correct repairs and quality workmanship. That was quite a few years ago. Gnarls.
https://www.gsparkplug.com/shop/spark-plug-construction/
So I saw a version of this where it only occurred on one side of the engine. Explanation?
You show Me and I will explain.was it a engine with NGK on one side and Nippo on the other?
https://www.tacomaworld.com/threads/why-after-10k-miles-are-my-spark-plugs-burnt.204481/All Denso. Pics are about halfway down the page
What You have found is perfectly normal. I have seen this on tons of spark plugs. It has little to no affect on anything. It is caused by a small amount of combustion gasses leaking past the sealing material between the ceramic and the steel shell. It is very common on plugs that have been installed for long periods of time.
What do you consider a long time six week, six months, six years? so you are telling me that it was only "A LITTLE HOT GAS" escaping. OK you are the expert. Now Expert tell me how an escaping gas can be hot enough to burn Ceramic insulator but too "COLD" to bother the "PLASTIC" coil pack that it is trapped inside of?Since the insulator in the plug is designed to operate in a temperature of 932 to 1472 Degrees F, the gases would have to pretty hot to burn the ceramic.
#1 A long time based on Mileage. several Toyotas call out for the first spark plug change at 120k miles (a long time)
They're showing corona stain as an even discoloration.So, I would assume if it's streaky, it's exhaust leakage..... (along with some corona staining)
Started by BigMike 1989-1995: How-To Guides
Started by Yota87Truck Chit Chat Camp
Started by acerbis Toyota Pickup/4Runner Tech 1979-95
Started by emsvitil Toyota Pickup/4Runner Tech 1979-95
Started by Michael Wollinsky Toyota Pickup/4Runner Tech 1979-95