Harold, my van is a '91 and had 166k miles on the original heads and gaskets.
 When I bought it, I drove it for a whole year and added no coolant at all.
About a year ago it started needing coolant, but only a little.  I guess this
was the only warning sign that I had.  The head gaskets looked fine
externally until the one blew.
It blew catastrophically so no amount of "Bars Leak", etc. would have done
any good.  Upon removing both gaskets and heads they were both in failure
mode as both were very dry rotted and cracked up on the top in one spot and
in the bottom in another spot and the heads were very pitted.  I had actually
been saving up for a rebuilt motor from Boston Engine that I was going to try
to have ready to go in at my leisure within the next few months (have to
start saving all over again).

So if I had it to do all over again I would have installed the rebuilt motor
before my trip and actually saved alot of hassel (of course I wouldn't have
had an adventure either :).  I think if you have a 2.1l engine with over 150k
miles on it that you better start saving up for a rebuild and do it before
175k miles because that seems to be the average time for a 2.1l to throw a
rod.  I mean now I have a motor with two new heads and gaskets but the bottom
end is still as tired as ever.  I am still looking to replace the motor
before this summer and before one of the rods get claustraphobic :)
1.9l motors have a stronger bottom end so at 150k miles I would feel
comfortable replacing gaskets and heads and running her another 50k miles or
so (untill she starts loosing compression) without worrying about
catastrophic failure (have you ever heard of a 1.9l throwing a rod?  Not
common like it is with the 2.1l).

So before this trip I would have said the same thing.  "If it ain't broke
don't fix it".  However after this trip I would have rather done the PM on my
terms and when I wanted to rather than 800 miles away from home in the middle
of my "vacation".

Hope this helps,
Ken Wilford
http://www.vanagain.com
John 3:16
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