OT: timing belts

From: Joe R. <rigdonj_at_cfl.rr.com>
Date: Sat Dec 25 10:59:37 2004

At 09:43 AM 12/25/04 +0000, you wrote:
>Joe R. wrote:
>> The '68 chevy didn't use a timing belt, it used a timing chain. Just
>> like all the REAL American cars! Personally I wish they all still did. I
>> hate these stupid rubber timing belts! All they're good for is generating
>> revenue for the delaers when they slip or break and you end having to buy
>> half of a new engine or a new car.
>Well, that's just down to stupidity.

  Tell me how it's supidity when you have a factory belt installed by a
factory trained mechanic and it jumps timing with less than 1000 miles on
the new belt and destroys half the engine! I'm waiting for an answer!

   That's what happened to me with my Nissan Maxima. The engine had to be
removed from the car in order to remove the rear cylinder head. I had to
replace values in both cylinder heads. The cost was over $1200 (in 1987!) I
was just lucky that it didn't also ruin some of the pistons and/or cylinder
heads. I've worked on hundreds of cars and I've NEVER seen anything like
that on an engine with a timing chain. The chains will stretch and change
the timing but they don't jump or break and destroy the engine.

  A new timing belt costs a tenner
>at the most

  Hah! Just bought one for my Mitsubishi Diamonte. $170+ ! Plus 3.5 hours
of labor at $99/hr. The last several that I've bought have all been over
$100 except for the one for the Subaru and it was $80 something (ten years
ago!) IIRC the one for the Maxima was $120+ in 1987!

   Also just had one changed on my daughter's Daewoo. They want you to
replace all the related tensioners, pullys, etc at the same time. Those
parts alone were almost $500!!! I was lucky in that the car still had 3000
miles left on the warrenty. The belt broke in that one at 57,000 miles and
the cost to fix everything was over $1200. I still have the paper work and
can show it to you if you don't believe me.

   In the mean time, my Nissan truck with a timing chain is still running
fine at 158,000 miles!

and even on an absolutely evil b*st*rd of an engine to work
>on (step forward, Citroen XM 2.5TD, not nearly as nice an engine as the
>CX 25DTR) it takes at worst a couple of hours to fit. I can do Volvo 2-
>and 3-series belts in about half-an-hour...

   I wish you'd come do the belt in my Mitsubishi! I'd PAY to see someone
change it's belt in 1/2 hour!


>It's cheap, it's important, and it's something you can easily do at
>home. Got to be a bit careful with diesels, though - sometimes you need
>a locking tool to stop the pump moving. I change them on any car I buy
>as a mere matter of course - think of it as (and here is where we swerve
>briefly ot ON-topic) similar to pulling all the boards from a classic to
>make sure the power supply isn't putting out the wrong voltage, the
>first time you power it up.
>As to why we use timing belts, well... The problem with timing chain
>designs is that the chains wear and go slack. This means you either
>need complicated hydraulic tensioners (like on the Peugeot/Renault/Volvo
>B27/B28 V6 as fitted to Volvos 260s, Renault 30s, Deloreans and the
>like, or Maserati V6es as fitted to Citroen SMs, or Triumph Stag V8s -
>all notorious for timing chain failures), or just allow the chain to
>slop about once it's worn (pretty much every other OHV chain-driven
>engine). The problem with that is that if there is a lot of slack in
>the chain, the position of the cam shaft (and hence the valve timing,
>and on most OHV engines the ignition timing) can be out by as much as 5
>degrees. If you've ever fitted a timing belt or chain to a car one
>tooth out (ummm, nope I've *never* managed to do that, then wonder why
>the engine was really quiet but down on power) you'll know how much of a
>difference that can make. Now imagine that instead of being "out" by a
>fixed amount, it's randomly flapping backwards and forwards plus or
>minus 5 degrees...
>Of course, the Ford Essex 3 litre V6 in my Scimitar solves the problem
>by having no belts or chains at all - just two big gears. The large
>gear uses fibre teeth which wear after a few hundred thousand miles, but
>that's another story....
Received on Sat Dec 25 2004 - 10:59:37 GMT

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