Car is 96 Merc Sable S/W w 3.0 engine. It's emitting a noise that
sounds just like a siren. It started out as just a humming sound some
months ago. I finally got tired of the noise and decided that it must
be the power steering pump, so I replaced it, along with the
serpentine belt. (I was careful to bleed the pump.) Immediately the
sound increased to a loud siren-sounding noise. I figured it might be
a bad replacement pump, so I got another one and put it in. Same
thing, just slightly less noisy. The sound is coming from the right
front corner of the engine. It is really loud. You can hear my car
coming down the road a hundred yards away. Again... it is a
high-pitched sound very much like a siren.
BTW, the A/C does not work. But I don't know when it went out. Last
time I used it was in September.
Could it be the A/C compressor or clutch? I've never heard one making
this kind of noise though. The noise is so loud I cannot pinpoint
exactly where it's coming from. I'm a bit worried that it may be an
internal problem in the motor itself.
probably a bearing in the idler pulley or tensioner pulley. could be any
of the things in the front of the motor(water pump, ac comp,alternator).
Use a long screwdriver, one end on your ear, the other near the pulley
(CAREFULLY)you think it might be. As bad as it sounds you will find it
easily. You can also remove the belt and spin the various pulleys by
hand to look for looseness, roughness.
Yea, what SS said.
Thee AC clutch or any other item in front can lock up and break the
belt, leaving you stranded. You have waited way past the grace period
on this noise.
You could leave the belt on and sound around various areas listening
with the handle of a long screwdriver against your ear. This is very
effective, yet very dangerious. I would not advise you to do it as you
have not done it before. Someone with experience could quickly pinpoint
where the noise is coming from.
PS. Just because the AC doesn't work and is never turned on anyway does
not prevent that bearing from seizing in front.
You can use a length of broomstick and touch one end to each of the A/C
compressor, alternator, power steering pump, idler, etc. with the engine
running, idling, with the emergency brake on.
Check anything that spins with the engine, and put your ear on the other end
of the broom stick. The loudest noise is a good indication of a bad bearing
on that component. Be sure not to get anything caught in the belt like
clothing, hair, jewelry, etc.
I have a mechanics stethescope, but a broom stick, long screwdriver, or
similar item can be used. Just stay clear of the belt and pulleys.
My bet is on the A/C clutch bearing. I/ve had a couple go
bad. Almost always eats the node off the compressor. My
wife drove the first one a couple of weeks after the noise
got bad before she said a word to me.
If it turns out to be the A/C compressor, is it better (cheaper) to
have the mechanic replace the clutch or the whole unit. I got a price
on rockauto.com of $200. The clutch is much cheaper but I have to pay
labor on the repair. Just wondering what you would do.
Oh... will they have to re-charged?
Both failures I've had ate the nose off the compressor case
requiring the compressor be replaced. Yes, it will need to
be replaced and recharged if this has happened. The only
way to know the extent of damage is to pull the clutch from
the compressor. You probably need to access it thru the
inner fender panel.
Either way you will have to pay the full labor, unless you do it yourself. On
car you will likely have to remove the compressor whether for the clutch or the
compressor assembly. The AC will have to be serviced also. If the shop follows
AC service cnvention, don't be surprised if they quote a price for replacing the
accumulator. It's good practice to replace the 10 year old accumulator when the
system is opened. It's kind of like the oil filter on the engine, it is a wear
It "should" be replaced but "can" be reused. (that's the closest analogy I could
of, I don't reuse oil filters and have reused accumulators on occasion) Also,
expect the shop to use the $200 compressor from Rock Auto. Expect to see
the part. A reputable shop will use a New compressor and they will see a bit of
up on the price.
I'm tring to understand this, we have a 100% failure, it should be easy
to isolate. I would soak idlers with oil and anything in the belt
system till I found the failed bearing or whatever... Now that we have
it that it is coming from the right side of the engine... Pulley
system. Once in the position of looking right to left at the passenger
side with the engine running is the noise coming from the right or
left? Right you have the AC and the PS with the ALT in the middle. You
should have an idler directly down between the ALT and the PS. This
noise is coming from the left or right as looking from the passenger
side front tire? I might be just running my mouth off but it's time to
isolate the device...
You said the AC did not work. If it's the AC clutch and you want air
then you need to have it fixed. However, if just handling the immediate
problem is the objective, they used to make a dummy pulley and bracket
that would replace the AC. I can't recall if it was from Ford or an
aftermarket supplier. The part was about $50 a few years ago.
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