95 4Runner 4X4 3.0. I replaced my plugs about a year ago, and thought I'd check for a blown head gasket this past week first removing the plugs and checking for discoloration. I did notice that the #6 plug was brown in color, compared to normally white. Anybody know what's going on? I thought a blown head gasket would make it look cleaner from the antifreeze getting in there, not brown or burnt looking.

 

You said you'd "check" for a blown headgasket, or do you have a blown head gasket?

IF you had a blown head gasket you'd probably know it. Your truck would be billowing white smoke, it would run rough, and you'd have milky oil.

I think your plug being brown in #6 could be from heat - perhaps your exhaust valve is on it's way out? Also, maybe you need to go back to stock Denso or NGK plugs.

 

I put 100,000 miles on a set of Bosch Platinums in my 3vze without a hiccup.

You CAN have a problem with a head gasket on it's way out without experiencing the rough running/billowing smoke/etc. Different coloration on ONE plug can indicate many different problems that one cylinder is experiencing.

Here's some links to pretty good tutorials on plug reading:

http://www.4secondsflat.com/Spark_plug_reading.html
http://www.mg-tri-jag.net/tech10.htm
http://www.nightrider.com/biketech/spkplghnbook.htm
http://www.ngksparkplugs.com/techinf...000&country=US

 

I'm doing a compression test today to see where I'm at. I thought that a Toyota engine could blow a head gasket without the coolant and oil mixing. I was told that the coolant seeps back into the compression chamber after it is turned off...hence a blown head gasket. I'll let you know. Brian

 

You bought a toyota engine to try and blow the headgasket?

 

IIRC the Bosch plugs are designed to run at a higher temp thus the reason you should be using NGKs.

 

JAPANESE PLUGS FOR JAPANESE MOTORS. GERMAN PLUGS FOR GERMAN MOTORS!!!!!!!!!! WHAT WERE YOU THINKING? NOTHING WORKS BETTER IN TOYOTA MOTORS THAN ND OR NGK PERIOD. I HAVE BEEN WORKING FOR TOYOTA FOR 16 YEARS.
JUST MY 2 CENTS
Now as to your problem. first get a factory cap, rotor, wires, and plugs. #19101-65040, 19102-70160, 90919-21579, 90919-01176. the factory wires are date coded more than 5 years and it's time for new ones. then run a compression and leakdown test. compression no more than 10% variation between cylinders. leakdown no more than 10%. if the tests are ok then the correct ignition parts should remedy the problem. poor fuel can also cause strange plug deposits.

 

Bosche Platinum Plugs suck ballz! I had them and will NEVER put them in another vehicle I ever own...

Getcha some NGK double platinums and dont look back...

 

i concur BOSCH PLATINUMS suck in anything other tahn what they were designed for-germans-stay with ND or NGK for your asian rides.I too work at Toyota.No telling how many "brand new" bosh platinums for customers after theyve done their own "tune up some get pretty peeved when you tell them their plug choice sucks-but are happy after making a believer out of them