</font><blockquote><font size="1" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">quote:</font><hr /><font size="2" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">Originally posted by elripster:
<strong>Example of 4 cylinder issues. There's a post up on this board where a guy test drives a turbo 4runner. It has a new head, cams, etc.... at 116K miles. Come on guys, if that's all the fight 4 cylinder is going to put up aside from being cost prohibitive, might as well turbo/super charge the V6.

Frank.</strong></font><hr /></blockquote><font size="2" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">Frank, my thoughts are, a V6 headgasket failure is the symptom of multiple causes and its not just the headgasket. Any time a component bears the bulk of stress due to other factors, its gotta be hell for stout or she'll go. In the case of the V6, I think you nailed it: block deck and head surface must be perfect, head torque must be perfect, and gasket must be perfect, because none is overbuilt. Add a headgasket design change to surfaces that are right at the tolerance limits but not outside them (QA is not black and white, after all) and you get additive out-of-tolerance issues leading to failure. Nail the tolerances to, say, 1/10 of manufacturing limits, darn the cost, and use a very good and expensive headgasket and you have a very reliable motor.

Toyota has to gamble every time they design something, and this time or that time the odds added to each other and they got bit. Any iron deck/aluminum head design is vulnerable, you just have to overbuild it or get it to a gnat's hair of perfect and some of the V6s and I4s whiffed it. Not to mention dealers who don't get it quite right when they change 'em...

Get it absolutely perfect and use the best components and you could probably blow it. But sheesh, that's a lot of work and not cheap compared to alternatives... <END OPINIONATING MODE>

<small>[ June 20, 2003, 10:30 AM: Message edited by: Bill_Morgan ]</small>