NG engine making a knocking noise when cold and ocassionally when hot.

[Jim Green]

--- Robert Stirrat <Robert_Stirrat at DMCWave.com> wrote:
> Hello,
>          This is a question for the oily-handed
> amongst you.   My 92 Series
> III Coupe has started to make a knocking noise from
> the engine, about five
> or six knocks can be heard when I start it from
> cold.  When I run rev the
> engine by pulling the throttle cable, one or two
> knocks can be heard.  It
> sounds to me that the noise is coming from the top
> end at cylinder 5.  There
> is no loss of power or oil pressure from the block.
>
> I took it to a local garage, they had a look at it
> and seem to think it
> coming from the bottom end, and said they'd need the
> car for two days to
> drop the sump and check the shells.  Is this likely
> to be the crankshaft
> bearing shells or the connecting rod shells?

If it sounds like somebody is wacking the top of your
engine with a large hammer, it's probably a bad rod
bearing.  It could be a crank bearing since the noise
goes away when it warms up?

> Is there anything else it is likely to be?

Not really.

> I should mention that I also had a ticking sound
> from the lifters, this
> prompted me to check the oil level.  Curiously, this
> was below min, curious
> because I had the oil changed some 6K miles ago, and

Umm, 6k miles?  Your car could easily go through 2
quarts of oil in that time, plus if that's you regular
schedule, you probably do have some botom end wear.
3k miles is the max I ever go between changes.  My
lifters always let me know around 2k miles that my oil
needs changed soon.


> also curious because I
> don't have any leaks.  I topped up the engine with
> .75 litres and the
> ticking has gone.  You may also recall I had a
> misfire on cylinder 1
> recently which I sorted with a replacement lead.
>
> I'm telling you this as I am wondering any of this
> symptoms were
> contributary to the onset of my engine noise?
>
> Will the connecting rod and crankshaft bearing
> shells be replaced as a
> matter of course along with the sump gasket when the
> garage carries out this
> work?  Is there anything else I should insist upon
> them replacing when the
> have the bottom end apart?

If they have to replace any bearings they will have to
pull the crank out , which means dropping the
transmission, or pulling the engine which would be
best.  If you do have a bad bearing you want to make
sure you get all the metal shavings cleaned out of you
engine.  You may also look at a new clutch while your
in there.

HTH

=====
Jim Green
'89 90tq EFI
http://www.geocities.com/jeg1976/car_home.html

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