Re: Strange noise in enginebay

["content22207" <brobertson@xxxx>]

An honest to goodness whistle is usually a vacuum leak. A high pitched
whine is usually bearings. Belts can squeal too (especially when old,
cold, or wet).

Late in message you indicate is worse at lower RPM's -- characteristic
of vacuum leaks. Early in message you indicate increases with RPM's --
characteristic of bearings. 

Use a piece of heater hose like a stethescope and listen all over
engine to pinpoint source of noise.

Symptoms of leaking head gasket are misfires, steam in exhaust, foam
or milky white residue in oil, rust on spark plug electrode, and
sometimes you can smell antifreeze (though odor is usually stronger on
external leak). Doesn't really make a noise other than engine running
very badly.

Overflow tube on coolant expansion tank should only be wet as system
reaches homeostasis (after fluid added). If antifreeze ever boils,
will come out many more places than just that little tube.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, Jan van de Wouw <jvdwouw@xxxx> wrote:
> Hi,
> 
> While driving this afternoon all of a sudden I heard a strange
> noise from the back, it sounded like a sort of "shrieky whistle"
> and increased with giving more throttle.
> 
> First thing that came to mind was the blowoff from the cooling,
> caused by a blown head gasket, so I stopped immediately...
> My coolant was still in the system, under pressure and the
> blowoff hose was dry. My oillevel was still right and there
> was no foam evident on the oil...
> I guess I can rule out the headgasket...
> The temp on the Gauge was on the "7:30"position, where it's been
> all day (runnning the A/C and driving no faster than 50mph...
> 
> When I listen in the engine bay and give throttle at the spool
> the sound seems to come from the left front, with the covers
> down it sounds like it's coming from the right rear :-S
> 
> My belts are both intact and under the right tension, the fins
> on my Alternator are all straight and don't hit anything...
> 
> Could this "whislte" come from an exhaust gasket?
> I have a leaky gastket between the right hand manifold and block
> nearest the X-over pipe (will be fixed after next weekend),
> could a gasket be "whistling"?
> 
> I really don't feel comfortable with my car right now; I drove it
> home as it was only 20 miles, so a tow would be easy if neccesary.
> The sound went away after a couple of miles, but returned when
> I drove into my neighbourhood...
> 
> Next weekend there's an event I'm supposed to go to, but that's
> 125 miles from here, so I'd like to know what this could have been
> before I drive off, running the risk of something REALLY going kaput.
> 
> I'm under my car anyway next wednesday, as I'm installing an extra speed
> sensor on the driveshaft then, so I'd like to know where I should look.
> 
> It'd be a real shame if I had to get into my '92 Nissan next week,
> to drive around next to cars that are 10 to 15 years older :-(
> 
> Thanks up front,
> 
> JAN van de Wouw
> Thinking Different... Using a Mac...
> Living the Dream... Driving a DeLorean...
> 
> DMC-12 "Dagger" since Sep. 2000
> 100NX "Saphire" since Nov. 2002
> 
> -------------------------------