Hey All, Well discussed topic but thought I'd throw in my few comments and questions from a hands on job of replacing them.
1995 4Runner SR5 - 3.0 Auto. Manufactured 5/95 - After the recall date. With the "fixed" head gasket design. 121K miles.Symptoms - Few days back by Runner started missing at idle and through full throttle pull. Would clear up for the most part after about 15 minutes running. I also had to start adding small amounts of coolant to the overflow, about a pint about every other day. Replaced the plugs and noticed #6 spark plug looked mucho different than the others. Darker with crude on the insulator. The new plugs helped, especially during full throttle pull but truck would still idle rough at startup, but usually cleared up. Looking at more things I found that I could see bubbling in the overflow after a small run. Did a "sniff test" for exhaust gasses in the radiator that really was not definitive, did not turn completely yellow but did turn clearish. My theory was that my head gasket/s were seeping a bit into #6, not bad but enough to make #6 miss until the coolant was burned off then at shutdown start the process all over again. I decided tear into it.
Since the truck was manufactured after the recall date I made no attempt to push Toyota into covering the fix. I also am second owner of it. I bought the truck knowing full well the head gasket problems with this engine and purposely shied away from the earlier manufactured dates when shopping for it. I am disappointed but not holding a grudge against Toyota for it. I would also like to state that I have not really abused the truck and have taken extreme care of it. I have recently started pulling a trailer usually with 2 dirtbikes well within the rated towing capacity of the truck. (MDT Tech- saw your posts in TT welcome to the Yamaha Thumper World! WR426 here.) To maintain 65 mph on the freeway for a couple recent trips with OD off the truck had to turn about 4000 RPM for extended periods. At no time has this truck overheated. This may have been the push the gaskets needed to go?
Repair : Using genuine Toyota parts... Head Kit $277 Water Pump while at it $121. Oil. Filter, Coolant .... Total bill for head gasket Toyota Parts $477. While at it and since I do not want wrestle with the damn crossover pipe again and hopeful pulling performance gains I'm installing a set NWOR headers and Y-Pipe and free flow Cat. Genuine Toyota the rest of the way out. Another $1300. Saving $700 to $800 labor by doing the job myself.
Tear down: Let me start by saying that this is probably one of the biggest mechanical challenges I have ever done as an amateur wrench. I took on this task because I had the time and didn't have the money to pay someone to do it AND buy new exhaust system. Unless you have lots of patience, good set of tools and are mechanically inclined I do not suggest tackling this job yourself. It is a pain. I won't go into the details unless asked.
Observations: Before pulling the heads off I could detect coolant in seepage on left head in the valley at 4 and 6 cylinders. After pulling the heads the left head gasket although not catastrophic in failure there was deformation of gasket around the water jacket holes near #6 cylinder. I think I thwarted the big failure by getting into is early. On removal of the right head I was surprised to see about a golf ball sized glob of gray looking mud sitting on a spot near the #5 cylinder? Anybody know what the hell that's about?
I'm know basically all back together and waiting on the headers to arrive to finish up the job. Does anybody have any comments on the NWOR headers? Performance gains? Good or bad welcome. I'll post a follow up once I get her back together and running.
Regards, R.