Date: Sun, 24 Jun 2007 09:50:25 -0400
Reply-To: Benny boy <huotb@VIDEOTRON.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Benny boy <huotb@VIDEOTRON.CA>
Subject: Re: Timing Chains, Belts, Gears, etc (NVC)
On most car/van the belt is protected by a dust/dirt sealed plastic cover,
of course, this one is there to prevent "stuff" getting IN the closed
section of the T-Belt
(i'm using a Subi picture because it's all i have now)
http://www.benplace.com/85rouge/subi_engine2.jpg
http://www.benplace.com/subaru/vanaru38.jpg
So, if something sharp enter the belt area, there is some chance that you
can dammage the belt. Another reason is a faulty/to hold belt tensionner.
I have also seen a faulty (mostly to hold) water pump cause belt failiure.
But again, those belt are extremely strong, even with missing part on this
one they can still go one for a long time, that is why a belt inspection
should be recommended.
In the case of a poor rebuilt, i have seen camshaft seized and the belt
broke of jump teeth, but in that case, it was to late anyway for the head.
The worse case of breakdown on interference engine (that mean that the
pistons CAN hit the valve) is a hole/dent in the pistons. Now, many will
say/ask why is those engine are of an interference design! well, a high
compression ratio (pistons closer to the head, even almost molded to this
one), this is also why modern engine use thinner oil, the space between the
crankshaft and bearing is so tight that thick oil would no pass.
Why not an external chain, of course, chain need lubrification, so motor
that use a chain habe this one inside the engine and use the internal motor
oil to self lubricate. Now chain do wear also, and a chain replacement is no
easy task. So yeas, gears would be nice... but!
The Subi is a good example of a long belt as this one as to go to both
heads, it also drive the water pump.
So, that said, when you change a T-Belt, you also need to change the water
pump, guide-bearing and sometime, the tensionner.
Now, about our wasser, like we all know don't have T-belt, gears or chain.
http://www.benplace.com/85rouge/subi_vw2.jpg
http://www.benplace.com/head3/100_0016.jpg
The cam in inside the case, under the crankshaft instead of being in the head.
So we use 8 solid pushrods tube to move the valves in the head. That design
is old and engineer found out that Over Head Camshaft was the future (short
Story).
Most timing belt can be easily inspected once a year, same goes for pushrod,
i have seen my share of bent pushrods.
Like i said yesterday, many of you have T-belt in your car, i'm also sure
that maybe 25-50% of you don't even know you have one.
So in the case of you friend, it may have been anything.
Some very high performance engine use compress air or oil to drive the valves.
Paris Dakar, Baja vehicle that race in the sand... they have T-Belt.
You can also cross the street, get hit, and die. Life is a risk.
Ben
On Sat, 23 Jun 2007 08:06:37 -0500, Larry Alofs <lalofs@RCN.COM> wrote:
>So, if a belt breaks before its time and it's not because of a flawed or
>underdesigned belt, what is the cause?
> "Operator error"?
>
>A friend of ours just had the belt break on their 2001 PT Cruiser. The
>repair quote estimate is $1200.
>I don't know the mileage; I assume it's non-interference.
>Larry A.
>
>
>Benny boy wrote:
>
>>I will rephrase, let's say that when they break before their time, it's not
>>because of the belt itself. But i have never seen one myself, your a lucky
men.
>>
>>Ben
>>
>>On Fri, 22 Jun 2007 14:39:36 -0700, Robert Fisher <refisher@MCHSI.COM> wrote:
>>
>>
>>
>>>--snip--
>>>
>>>
>>>
>>>>Sorry guys but a timming belt does't break, that's urban legend.
>>>>
>>>>
>>>--snip--
>>>
>>>Don't know where you're coming from with this Benny, but if that's an urban
>>>legend I'm living in the Twilight Zone. I've personally had two timing belts
>>>break before their 'time' (one in a Rabbit diesel- that one destroyed the
>>>head) and more recently I knew a guy that had a late-model Mitsubishi (iirc)
>>>that busted a belt at around 30K.
>>>
>>>Cya,
>>>Robert
>>>
>>>
>>
>>
>>
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