Why 12 month oil change on low use vehicle? - Page 3

On Wed, 19 Jan 2011 23:00:38 +0000, DavidR wrote:


As has been mentioned several times already, the greatest wear to a cam
belt happens at the moment the engine starts cranking, and the camshaft
has to be moved from rest. In fact, sometimes with a belt near the end of
its life it will jump a tooth; it only ever happens at start-up.

Lots of short journeys means lots of extra starts...


AFAIK, every service schedule quotes x miles, or y years, whichever comes
first.


?

Chris

--
Remove prejudice to reply.

Chris Whelan wrote:

I came across a very good example of the problem of low mileage belt
failure:  A Corsa 1.4 16v came to me with belt failure and all the valves
bent.  It had 30 something thousand miles showing and was 6 years old.
Never had a belt from new.  Recommended is 40k or 4 years, at 4 years old it
had 17k showing.  The cause of failure was the water pump bearings had gone,
allowing a slack belt to slip teeth.  I questioned Vauxhall on this and the
top tech at the local place said he had seen it many times on corsa/astra
used for short journeys/ irregular use, apparently the water pump bearings
get damp and rust leading to premature failure, regular use stops this
happening.  He said it should have had belt kit and water pump at 17k.
Which is rather expensive motoring afaics.  Incidentally although the
bearings had gone there was not a trace of water leakage, showing that the
inner seal was still working, even though the outer one had gone missing
along with all the balls.

Not necessarily. Typical grannny driving behaviour is one cold start, drive
to the shops, park, one warm start, drive home. 2 starts, one of them cold.

Yummy mummy behaviour would be something like 2 school runs, 1 shopping
trip, and maybe a journey in the evening to take little Johnny to scouts.
Probably not more than 10 starts in the day.

Typical courier or rep driving may be to drive 100 miles or so 2 or more
times in a day, but he will also visit several customers, stop for fuel,
stop for lunch, stop in a layby to do paperwork and make phone calls,etc
etc. Maybe 20 starts in the day.

Steve



 

shazzbat wrote:

One start per mile, maybe one per two miles if she lives away from the
supermarket. Cambelt life limited by time. And the start on the way home
probably isn't a warm start, either, as it'll often be more than an hour
after she parks up. The car won't be serviced more than once a year, either.


One start per two miles on average. Cambelt life limited by time.


One start per twenty to fifty miles on average. Cambelt life limited by
mileage. The vehicle will also normally be serviced more regularly,
which should mean that the cambelt will be checked for wear, too.
--
Tciao for Now!

John.

shazzbat wrote:

and the repmobile never gets cold and gets serviced at least twice a year
and has a new belt every two, sounds good to me.

On Thu, 20 Jan 2011 10:08:08 +0000, shazzbat wrote:

[...]


Nope. Start in garage, reverse out, stop to use keys to lock garage.
Start, drive to post office to drop package off, stop. Start, drive to
chemist to drop prescription in, stop. Start, drive to supermarket, stop.
Start, drive to supermarket forecourt for fuel, stop. Start, drive back
to chemist, stop. Start, drive home, stop. Unload car. Start, drive into
garage, stop.

Total mileage = 8. Total starts = 8.

BTW, cam belt shock loadings occur whether the starts are with a warm or
cold engine, and might in fact cause more wear during hot starts.
 

Even 10 a day would be more than I would consider average. Start car,
drive to work, stop. Start car, drive home, stop. Two starts.

For the situation you are describing, a lot would depend if it was the
sole family car, possibly doing longer runs at the weekend, or just a
local runabout.


Indeed, but for those 20 starts, (s)he might have covered perhaps 200
miles. That's 1 start per 10 miles. versus 1 start for 1 mile for the
granny.

Two of the three scenarios you have described show exactly why low
mileage vehicles may well need more frequent cambelt changes.

Chris

--
Remove prejudice to reply.

No they don't. Cambelts are recommended to be changed at certain time and
mileage figures. If they were failing early as you and others claim, it
would soon come to the attention of the manufacturers (and their lawyers)
and the recommendations would be changed. If certain usage meant that more
frequent changes were required, that would be stated, yet to the best of my
knowledge it isn't. At least not such usage that would be specific to
low-mileage granny.

Steve

On Thu, 20 Jan 2011 14:48:41 +0000, shazzbat wrote:

[...]


<Shrug>

Yes they do. Choose not to acknowledge it if you like.


Some years ago, Ford introduced 100k/10 year intervals. Vauxhall
responded with a new Astra with 72K intervals. Few ever got near that
milage, so the interval was reduced to 36K. Is that not a case of belts
failing earlier than the service interval?


"Severe duty conditions:

Short trips of less than 10 miles..."

Chris

--
Remove prejudice to reply.

And of the recommendations being changed. this is stioll nothing to do with
granny.

Link?

Steve

On Thu, 20 Jan 2011 23:18:45 +0000, shazzbat wrote:

[...]


You snipped what I was replying to.

You stated "If they were failing early...the recommendations would be
changed".

My reply was to show you that cambelts *do* fail earlier than
recommended, and manufacturers *do* change their recommendations.

WRT early failure on vehicles with non-standard usage such as frequent
stop/starts, in spite of others with many combined years of experience in
the motor trade telling you the same thing, you simply don't want to
believe it.


If/when you become a low annual milage driver, it's your wallet...


What do you think this:

"<Checks Focus service guide>"

meant?

I don't have a link to the glove box of my car...

I'm sure this information would be available online, but if I went to the
trouble of finding it, you would simply refute it on the basis that you
can't believe what is written online.

Clearly this thread has drifted wildly OT; FWIW, I tend to support the
idea that condensation on the inside of an unused engine would be
unlikely to cause the sump to drop off. I think the poster's intention
was slightly tongue-in-cheek.

The evidence freely available regarding early cambelt failure on short-
journey vehicles is compellingly in favour of it being a cause however.

Chris

--
Remove prejudice to reply.

I knew there would be something we could agree on :-)

Steve

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "shazzbat"


Hmm... I recall the early Escort 1.6D vans - very simple cambelt
arrangement that endured much abuse and never broke. Just as well, as
the company I worked for hardly ever serviced them.
The 1.8D engine, otoh, the belts would break at 60K, give or take a
couple of thousand.
This was a courier company and the vans were in use almost round the
clock, some of the 1.6Ds reaching 250K.

Four things can happen to a belt:- failure of the structural webbing through
cyclic fatigue, tooth wear, chemical deterioration or indirectly through
failure of other components.

You use the word "wear" for  your scenario. This cannot be the case.

On Sat, 22 Jan 2011 01:42:40 +0000, DavidR wrote:

[...]


You've posted your usual pseudo techno-babble, but completely failed to
provide *your* definition of "wear", making your post pretty much
meaningless.

In the context of this thread, I've used it to mean a condition whereby
the belt's life if shortened. How does that not meet the things you have
described?


No; pretty likely however.

Chris

--
Remove prejudice to reply.

Oh, silly me. I was under the misunderstanding that motor companies employ
scientist and engineers. In future I shall have to bear in mind that they
use witch doctors to cast spells and parts need to be replaced when the
magic runs out.

I asked for something technical but you jumped in. I have no doubt that
patterns of use have significant influence on patterns of wear but some
things embedded in motoring lore have disseminated from half facts and
Chinese whispers. Some things leap out as needing further examination - to
discover whether it is just anecdotal or whether there is any solid basis.


I put the word "wear" next to the word "tooth"...

I'll make it simpler for you. If someone brings in a car for belt
replacement at the allotted mileage, the teeth will show sign of wear. If
someone else brings in a car at 4 years old that has only done 6K and is
scared into spending £300 by a spanner wielder that the magic has run out,
the teeth will probably not show any sign of wear.

Such things as "40K or 4 years" might have more credibility if was something
like "40K or 6 years". Moderate usage is not "harmful" (by whatever
definition you care to choose).

Cars are designed for roughly a 100K/10 year life. If a car only does 2K a
year, the fact it might be scrapped 80K short of potential is not a
disaster. Maintaining to book on the basis that it could reach 100K is
costly and pointless.


In order to establish why something failed, it is first necessary to see how
it failed.

It's not all about teeth wear, you know.

It's actually more likely that a little used car will throw the belt off
due to the rubber going stiff.

The time limit is there for a reason - because rubber will harden and
snap over time.

I'd prefer to change the belt at £300, rather than rebuild the engine at
4 or 5 times that cost.
--
SteveH

Now we're getting somewhere. Chris Whelan might be helpful with the
"something's broken, how do I fix it?" questions but he's rather awkward
when it comes to underlying matters.

However, this leads to another question...

When Ford fit a belt they suggest it can last 10 years whereas VW reckon
it's a bit manky after 4. Now, I can understand different engines having
different mechanical loadings but if it's a chemistry issue, surely someone
must be wrong?


Yes, but you seem to be speaking for yourself and I'm guess you're not
someone that does an unusually low mileage.

Actually, the last 2 VWs I owned were on 8 year changes - but sensible
people did it on 4-6 years, due to a few known issues of belts snapping
early.

Same applies to the Ford 10-year change. You may be lucky - or you may
be unlucky - but as it's only £200-ish for most belt changes with my
local mechanic, I'd prefer not to take the gamble - and would do it on 5
years max.


I have several vehicles - some are changed on time, some on mileage.

My Ducati (bike), for example, is well under the mileage limit - but is
coming up to the 2 year recommended change this spring.

--
SteveH

So I read that you're suggesting that Ford are being optimistic. If we can
assume that VW are pessimistic, then your rubber ageing mechanism has
credence.


On top of the additional cyclic loading due to the higher revs, the power
transfer is probably higher than directly proportional (might even approach
a square).

On Tue, 25 Jan 2011 23:23:57 +0000, SteveH wrote:

[...]


The service manager of the local Ford dealership is a personal friend. (I
went to school with him over 50 years ago!)

When my last Focus was about eight years old, I asked him if I should
consider changing the cambelt. He said they had never seen a premature
belt failure on a Focus, so I would be wasting my money. He also told me
that tensioners on early models sometimes failed, but in every case the
owner had agreed that it had got noisy before failure, so could be
predicted.

When the belt was changed at 10 years, and around 96K miles, it was
difficult to tell it apart from the replacement.

Chris

--
Remove prejudice to reply.