Bob_98SR5

erik,
youre in luck: i just finished a writeup on changing plugs

http://www.4runners.org/articles/sparkplugs

the driver's side plug near the firewall is a beotch. good luck w/ your big hands otherwise, a VERY simple job

bob

rdharper

In theory, electrolyis is an issue between Al and Fe. Current flow would most definitely see resistance given the high voltage surge that must pass between the threads and the block despite the current being spread over a much larger surface area. Put it this way, Al is a prime ingredient in rocket fuel for a good reason. It is highly active.

That having been said, my experience is the same as yours, although I average 60k before a plug change since we stopped using leaded gas. Even then, they rarely need more than regapping.

MTL_4runner

I don't want to get too far off on a tangent and hijack this thread talking about antiseize, but I'll say a few final things. First, you are correct, Al and Fe will certainly create a galvanic circuit, but like I said it really is not the issue it used to be because often manufacturers use steel inserts in the heads so there is no dissimilar metals issue in that case (with the plugs anyway). In the case where the threads are still aluminum, it is definately a good idea to be using a little bit of antiseize, but again it really only becomes an issue when maintenance is neglected for long periods since most plugs are also plated with nickel, zinc, cadmium or another protective metal which will delay the galvanic process long enough for routine maintenance schedules to allow for the safe removal/changing of the plugs. The NGKs and Densos are known to have very good corrosion protection so like I mentioned, I don't bother using antiseize for my particular maintenance schedule.

I am definately familiar with powdered Al in rocket fuel....have a look at my profile on YT.

rdharper

Jamie;

Be nice to know which engines have the inserts. Not only does it avoid the possibility we've been discussing, it is also less likely to suffer a cross-threaded start methinks.

984RNR

Another tip - When installing the new plugs twist to the left until you hear a "click" to make sure taht the plugs aren't cross threading. Lots of extensions on number six wil help.

Watrout88

I just found out that I am going to have to drop $1600+ because one my Bosch Spark Plugs came loose and striped all the threads on my head. The mechanic is trying to tell me that is was because I didn't tighten the spark plug tight enough. I had changed these plugs out about a year ago, why in the hell would it take that long for them to come loose? He is worried that some of metal might have gotten into the lifter seat.
Has anyone heard of this happening? He wasn't able to check for compression, but would it be worth it to re-thread the head, put a spark plug in and check for compression without taking the whole head apart?

Elton

:bigclap: bosch

toyota_mdt_tech

RIP, first off, Botched plugs are the worst. Get the ND or NGK's. Under $20 for all. Plug wires, forget aftermarket ones. They get creamy and come apart first time you try to remove it and ruin all AM reception. Get a set of OE wires for less money, yes, I said less! ANd they never come apart. We charge 1.0 for plugs and wires, that $90 on a 3.0 V6. Have a dealer do it, cheaper, higher quality parts too!

toyota_mdt_tech

Well said! I agree!

toyota_mdt_tech

I call them "Botched" plugs!