valve train noise or worse ?

Hi all,

I tried Brian's idea, but found that nevertheless most likely the big end
bearings are gone.

Thanks Nathan. Hopefully not a big repair, if the problem is still not so
old. But big end bearings wearing out can severely load connecting rods, and
lead to failures and break-ups, so I just read.

Thanks all,

Carl
"Peter" > schreef in bericht
...
> Hi,
>
> That's a thought. This gearbox has given me trouble in the past.
> When starting up the car again, I will try what it's doing under the
> conditions you describe.
> A way to find out is IMHO to disengage the clutch and see if the sound has
> gone. If it is engine bearings - whichever - the clatter should persist,
at
> least some.
>
> Thanks for the idea.
>
> Carl
>
> "Brian Stell" > schreef in bericht
> m...
> >
> > > It is loudest on a cold engine, and in the afternoon, with engine
still
> > > warm, is never that loud again. It also becomes very high in frequency
> when
> > > cold when the throttle is released, after driving in low gear and low
> load,
> > > the clatter increases just after release in volume and frequency, and
> > > diminishes after about a second ...
> >
> > I can see valve noise being influenced by RPM
> > (more RPM => more noise) but I'm unfamiliar with
> > valve noise being influenced by throttle.
> >
> > My experience with rod bearing noise is it is
> > loudest when accelerating / hill climing
> > (more engine power => more noise) and is quiet
> > when off throttle.
> >
> > I've been told the main bearings tend to be
> > noisy all the time.
> >
> > Now the "diminishes after about a second" makes
> > me think gear lash. As in something is spinning
> > and the normal resistance keeps the "front"
> > side of the teeth engaged. When going off throttle
> > the spinning item's inertia keeps it spinning so
> > the gear is bouncing between the "front" and
> > "rear" side of the teeth. When the engine speed
> > stops dropping it's back to resistance / "forward"
> > teeth. If the slowing is heavy then the inertia
> > can keep the "rear" side of the teeth engaged.
> >
> > Driving down a grade, off throttle, at a constant
> > speed would create a similar force on the bearings
> > as off throttle but no inertia / spinning changes.
> >
> > Do you get the noise under this condition?
> >
> > Or only when the engine is dropping RPM?
>
>

Hi Brian,

Seems we were at it at the same time :-)

No, this camshaft is belt driven, and it's not making noise. But your
analysis is worth remembering, and very much appreciated !

Thanks,

Carl
"Brian Stell" > schreef in bericht
om...
> > That's a thought. This gearbox has given me trouble in the past.
> > When starting up the car again, I will try what it's doing under the
> > conditions you describe.
>
> Does your car have a gear or chain driven cam?
>
> A chain could also produce a "bouncing" between
> "front" of the chain pulling against normal
> resistance and "rear" of the chain pulling
> against the inertia to slow the rotation during
> dropping RPM.
>
> Also, if the chain were stretched or the
> tensioner weak on dropping RPM the "front" side
> of the chain could loose and be flapping or
> banging around.
>
> Again the condition would be dropping RPM (as
> opposed to constant RPM with engine braking).

If you can drop the oil pan easily, why not pull one rod cap and
Plastigauge it, also see if you can "wipe" some copper on the rod
journal of the crank with a penny. (no copper transfer = good,
obviously.) If it passes both tests it's not the rod bearings, if the
clearance is large but passes the penny test OK just roll some new
shells in and try that.

I understand your concern that the rod bearings would be louder under
load, but honestly in the G60 they could be heard most distinctly at
about 3000 RPM, when the engine slowed down during a shift. It seems
counterintuitive but there you have it.

When you put the new shells in, use lots of brakleen or similar to make
sure that you don't have any varnish or gunk on the bearing surface of
the rods or caps (will tighten up clearances and interfere with heat
transfer) also crank the engine over with fuel disabled until the oil
pressure comes up before trying to start it, don't want to dry start
new bearings.

good luck,

nate

(I've probably just appalled all the real mechanics reading this forum,
but that's what I did with that G60 motor about four years ago and it's
still embarassing Hondas and breaking motor mounts <G> There's the
right way to do it, and then there's the way you can afford to do
it...)

carl wrote:
> Hi all,
>
> I tried Brian's idea, but found that nevertheless most likely the big end
> bearings are gone.
>
> Thanks Nathan. Hopefully not a big repair, if the problem is still not so
> old. But big end bearings wearing out can severely load connecting rods, and
> lead to failures and break-ups, so I just read.
>
> Thanks all,
>
> Carl
> "Peter" > schreef in bericht
> ...
> > Hi,
> >
> > That's a thought. This gearbox has given me trouble in the past.
> > When starting up the car again, I will try what it's doing under the
> > conditions you describe.
> > A way to find out is IMHO to disengage the clutch and see if the sound has
> > gone. If it is engine bearings - whichever - the clatter should persist,
> at
> > least some.
> >
> > Thanks for the idea.
> >
> > Carl
> >
> > "Brian Stell" > schreef in bericht
> > m...
> > >
> > > > It is loudest on a cold engine, and in the afternoon, with engine
> still
> > > > warm, is never that loud again. It also becomes very high in frequency
> > when
> > > > cold when the throttle is released, after driving in low gear and low
> > load,
> > > > the clatter increases just after release in volume and frequency, and
> > > > diminishes after about a second ...
> > >
> > > I can see valve noise being influenced by RPM
> > > (more RPM => more noise) but I'm unfamiliar with
> > > valve noise being influenced by throttle.
> > >
> > > My experience with rod bearing noise is it is
> > > loudest when accelerating / hill climing
> > > (more engine power => more noise) and is quiet
> > > when off throttle.
> > >
> > > I've been told the main bearings tend to be
> > > noisy all the time.
> > >
> > > Now the "diminishes after about a second" makes
> > > me think gear lash. As in something is spinning
> > > and the normal resistance keeps the "front"
> > > side of the teeth engaged. When going off throttle
> > > the spinning item's inertia keeps it spinning so
> > > the gear is bouncing between the "front" and
> > > "rear" side of the teeth. When the engine speed
> > > stops dropping it's back to resistance / "forward"
> > > teeth. If the slowing is heavy then the inertia
> > > can keep the "rear" side of the teeth engaged.
> > >
> > > Driving down a grade, off throttle, at a constant
> > > speed would create a similar force on the bearings
> > > as off throttle but no inertia / spinning changes.
> > >
> > > Do you get the noise under this condition?
> > >
> > > Or only when the engine is dropping RPM?
> >
> >

Hi Nathan,

Thanks. The oil pan cannot be dropped easily, and I'm not going to do the
work. Is there any guarantee that the wrist pins are never as quickly
damaged as the rod end shells ? It would severely heighten costs.

The counterintuitive reality is not so illogical, IMHO. There is a change in
load direction after the compression stroke when throttle is closed, and so
the movement causes a sound. With combustion the load is always positive.
Only at intake stroke should the load change but even then would a closed
throttle cause more shell noise. Am I right ?

What should I do if the penny test is not OK ?


Thansk again,

Carl


"N8N" > schreef in bericht
oups.com...
> If you can drop the oil pan easily, why not pull one rod cap and
> Plastigauge it, also see if you can "wipe" some copper on the rod
> journal of the crank with a penny. (no copper transfer = good,
> obviously.) If it passes both tests it's not the rod bearings, if the
> clearance is large but passes the penny test OK just roll some new
> shells in and try that.
>
> I understand your concern that the rod bearings would be louder under
> load, but honestly in the G60 they could be heard most distinctly at
> about 3000 RPM, when the engine slowed down during a shift. It seems
> counterintuitive but there you have it.
>
> When you put the new shells in, use lots of brakleen or similar to make
> sure that you don't have any varnish or gunk on the bearing surface of
> the rods or caps (will tighten up clearances and interfere with heat
> transfer) also crank the engine over with fuel disabled until the oil
> pressure comes up before trying to start it, don't want to dry start
> new bearings.
>
> good luck,
>
> nate
>
> (I've probably just appalled all the real mechanics reading this forum,
> but that's what I did with that G60 motor about four years ago and it's
> still embarassing Hondas and breaking motor mounts <G> There's the
> right way to do it, and then there's the way you can afford to do
> it...)
>
> carl wrote:
> > Hi all,
> >
> > I tried Brian's idea, but found that nevertheless most likely the big
end
> > bearings are gone.
> >
> > Thanks Nathan. Hopefully not a big repair, if the problem is still not
so
> > old. But big end bearings wearing out can severely load connecting rods,
and
> > lead to failures and break-ups, so I just read.
> >
> > Thanks all,
> >
> > Carl
> > "Peter" > schreef in bericht
> > ...
> > > Hi,
> > >
> > > That's a thought. This gearbox has given me trouble in the past.
> > > When starting up the car again, I will try what it's doing under the
> > > conditions you describe.
> > > A way to find out is IMHO to disengage the clutch and see if the sound
has
> > > gone. If it is engine bearings - whichever - the clatter should
persist,
> > at
> > > least some.
> > >
> > > Thanks for the idea.
> > >
> > > Carl
> > >
> > > "Brian Stell" > schreef in bericht
> > > m...
> > > >
> > > > > It is loudest on a cold engine, and in the afternoon, with engine
> > still
> > > > > warm, is never that loud again. It also becomes very high in
frequency
> > > when
> > > > > cold when the throttle is released, after driving in low gear and
low
> > > load,
> > > > > the clatter increases just after release in volume and frequency,
and
> > > > > diminishes after about a second ...
> > > >
> > > > I can see valve noise being influenced by RPM
> > > > (more RPM => more noise) but I'm unfamiliar with
> > > > valve noise being influenced by throttle.
> > > >
> > > > My experience with rod bearing noise is it is
> > > > loudest when accelerating / hill climing
> > > > (more engine power => more noise) and is quiet
> > > > when off throttle.
> > > >
> > > > I've been told the main bearings tend to be
> > > > noisy all the time.
> > > >
> > > > Now the "diminishes after about a second" makes
> > > > me think gear lash. As in something is spinning
> > > > and the normal resistance keeps the "front"
> > > > side of the teeth engaged. When going off throttle
> > > > the spinning item's inertia keeps it spinning so
> > > > the gear is bouncing between the "front" and
> > > > "rear" side of the teeth. When the engine speed
> > > > stops dropping it's back to resistance / "forward"
> > > > teeth. If the slowing is heavy then the inertia
> > > > can keep the "rear" side of the teeth engaged.
> > > >
> > > > Driving down a grade, off throttle, at a constant
> > > > speed would create a similar force on the bearings
> > > > as off throttle but no inertia / spinning changes.
> > > >
> > > > Do you get the noise under this condition?
> > > >
> > > > Or only when the engine is dropping RPM?
> > >
> > >
>