On Jun 15, 12:16*pm, George wrote:
On 6/15/2010 10:48 AM, DerbyDad03 wrote:





This question is about the decision process involved with replacing
the timing belt in a vehicle "now" or "later".

Let's not confuse the issue with cost or voiding warranties, etc.
Let's assume there is no warranty to deal with and that the cash is
readily available, both now and later.

Here's the situation a friend and I were discussing the other day:

The manual - and therefore the dealer - says the timing belt on his
vehicle should be replaced at 90K, which is right where he's at.

He called around to various repair shops for a price and multiple
places told him "I've never seen a timing belt go on that vehicle
before 110K. The dealers just want their money early. There's no need
to replace it at 90K." He was even able to "verify" that opinion on
the web.

OK, so let's say that you are planning to keep the vehicle for the
foreseeable future, probably well beyond 110K. That means that you
will need to replace the timing belt, probably in about a year, to be
safe.

So here's what I was thinking:

There's a pretty slim chance that you'll keep the vehicle for the full
life of the second timing belt. That would put you in the 220K range.
Even if you replaced it at 90K and it really will last 110K, that's
still pushing 200K.

Why would you wait until next year and not replace it at 90K? Even at
the dealer's "accelerated" schedule, you're good until 180K, by which
time you'll probably have gotten rid of the car, so why not be *extra*
cautious and replace it now?

Thoughts?

How lucky is your friend? Thats what it really comes down to since the
so called interference design is very commonly used. That means the
pistons can contact the valves if the engine goes out of basic time. At
that point unless it is a valuable car you sign the line on the title
that says "dispose as salvage" and leave it on the dash.- Hide quoted text -

- Show quoted text -

There has been a tendency towards a non-interference design in later
years. Older engines often had an interference design to maximize
compression. With a chain driven cam it didn't matter much. Overhead
cams lead to belts replacing chains since it was chore to enclose a
chain between the top of the head and the crankshaft. But a lot of
the early ones did still have interference valves. High compression
mostly went away with low octane gas so it is a lot simpler to have a
non-interference design now.