87 Alfa Romeo Spider - odd sound help plz

Hello group, I was hoping someone might be able to help me out with
this one... I've got an 87 Alfa Romeo, 43k miles. last week when I was
driving home the car would vibrate a little and make a sound like I was
driving down the rumble strip (that gap on the right hand lane so you
don't go off the road when you fall asleep) or one of those 4x4 trucks
with large knobby tires going by. it only happens when I go over 75
mph. I tend to average 75-80 on my way home. hasn't been a problem yet.
it does the same thing once it warms up and I go about 40 mph in the
city. my thought was a possible problem with the catalytic converter,
there's some rattle sound from it when you try to move it. it's an
expensive part and I wanted to see if anyone else might of gone the
same road, sort of say...
Thanks for any help

Regards

On Wed, 31 May 2006 17:40:31 -0700, Cableguy wrote:

> Hello group, I was hoping someone might be able to help me out with
> this one... I've got an 87 Alfa Romeo, 43k miles. last week when I was
> driving home the car would vibrate a little and make a sound like I was
> driving down the rumble strip (that gap on the right hand lane so you
> don't go off the road when you fall asleep) or one of those 4x4 trucks
> with large knobby tires going by. it only happens when I go over 75
> mph. I tend to average 75-80 on my way home. hasn't been a problem yet.
> it does the same thing once it warms up and I go about 40 mph in the
> city. my thought was a possible problem with the catalytic converter,
> there's some rattle sound from it when you try to move it. it's an
> expensive part and I wanted to see if anyone else might of gone the
> same road, sort of say...

Sounds possible, although it shouldn't really be speed related. Try
tapping it with a soft mallet. If the baffles have gone, you'll hear it.

--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
Alfa 116 Giulietta 3.0l (Really) Sprint 1.7 75 TS 156 TS S2
Triumph Speed Triple: Black with extra black bits
www.cuore-sportivo.co.uk

On 31 May 2006 17:40:31 -0700, "Cableguy" > wrote:

>Hello group, I was hoping someone might be able to help me out with
>this one... I've got an 87 Alfa Romeo, 43k miles. last week when I was
>driving home the car would vibrate a little and make a sound like I was
>driving down the rumble strip (that gap on the right hand lane so you
>don't go off the road when you fall asleep) or one of those 4x4 trucks
>with large knobby tires going by. it only happens when I go over 75
>mph. I tend to average 75-80 on my way home. hasn't been a problem yet.
>it does the same thing once it warms up and I go about 40 mph in the
>city. my thought was a possible problem with the catalytic converter,
>there's some rattle sound from it when you try to move it. it's an
>expensive part and I wanted to see if anyone else might of gone the
>same road, sort of say...

I had a couple of odd exhaust rattles on my 146. One was due to a screw
that had worked a bit loose, and the other happened because the heat
shield had got slightly bent and was tapping on something. Both those
tended to happen when idling, so probably not related to yours, but
worth checking before doing anything expensive.

--
Stephen Poley

Thanks for the ideas, I'll let you know how I make out.. ;-)



Stephen Poley wrote:
> On 31 May 2006 17:40:31 -0700, "Cableguy" > wrote:
>
> >Hello group, I was hoping someone might be able to help me out with
> >this one... I've got an 87 Alfa Romeo, 43k miles. last week when I was
> >driving home the car would vibrate a little and make a sound like I was
> >driving down the rumble strip (that gap on the right hand lane so you
> >don't go off the road when you fall asleep) or one of those 4x4 trucks
> >with large knobby tires going by. it only happens when I go over 75
> >mph. I tend to average 75-80 on my way home. hasn't been a problem yet.
> >it does the same thing once it warms up and I go about 40 mph in the
> >city. my thought was a possible problem with the catalytic converter,
> >there's some rattle sound from it when you try to move it. it's an
> >expensive part and I wanted to see if anyone else might of gone the
> >same road, sort of say...
>
> I had a couple of odd exhaust rattles on my 146. One was due to a screw
> that had worked a bit loose, and the other happened because the heat
> shield had got slightly bent and was tapping on something. Both those
> tended to happen when idling, so probably not related to yours, but
> worth checking before doing anything expensive.
>
> --
> Stephen Poley

In article .com>,
"Cableguy" > wrote:

> Hello group, I was hoping someone might be able to help me out with
> this one... I've got an 87 Alfa Romeo, 43k miles. last week when I was
> driving home the car would vibrate a little and make a sound like I was
> driving down the rumble strip (that gap on the right hand lane so you
> don't go off the road when you fall asleep) or one of those 4x4 trucks
> with large knobby tires going by. it only happens when I go over 75
> mph. I tend to average 75-80 on my way home. hasn't been a problem yet.
> it does the same thing once it warms up and I go about 40 mph in the
> city. my thought was a possible problem with the catalytic converter,
> there's some rattle sound from it when you try to move it. it's an
> expensive part and I wanted to see if anyone else might of gone the
> same road, sort of say...
> Thanks for any help
>
> Regards

Could be any one of several things. Could be an out-of-balance tire.
Could be a bad 'giubo' (rubber drive-shaft coupling), could possibly be
a broken exhaust mount (but from your description, I don't think so).
Lemme ask you some "Q's". Do you feel this vibration through the chassis
to the seat of your pants, or do you feel it through the steering wheel?
If its the former, is it worse when you put your hand on the drive shaft
tunnel between the seats or is it the same no matter where you touch the
car? If its not through the steering, and is the same everywhere that
you touch the chassis, then its likely a rear tire out of balance, If
its through the steering, its front tire or suspension bushings. If its
worse through your hand when resting your hand on the drive shaft
tunnel, the a giubo has either thrown a chunk loose or a broken piece is
hitting something as the shaft turns.

--
George Graves
The health of our society is a direct result of the men
and women we choose to admire.

"Cableguy" > schreef in bericht
oups.com...
> Hello group, I was hoping someone might be able to help me out with
> this one... I've got an 87 Alfa Romeo, 43k miles. last week when I was
> driving home the car would vibrate a little and make a sound like I was
> driving down the rumble strip (that gap on the right hand lane so you
> don't go off the road when you fall asleep) or one of those 4x4 trucks
> with large knobby tires going by. it only happens when I go over 75
> mph. I tend to average 75-80 on my way home. hasn't been a problem yet.
> it does the same thing once it warms up and I go about 40 mph in the
> city. my thought was a possible problem with the catalytic converter,
> there's some rattle sound from it when you try to move it. it's an
> expensive part and I wanted to see if anyone else might of gone the
> same road, sort of say...
> Thanks for any help
>
> Regards
>

Is the sound speed or rev dependent?
If it's rev dependent 'look for something in engine/gearbox area.
If it's speed dependent look for something in driveshaft/rear axle
My guess it's the so-called guibo, the rubber X-connection in the drive
shaft and/or the intermediate bearing of the drive shaft.
Dried out / old rubbers most likely; straight forward DIY job.
--
Ciao from The Netherlands
alfistagj (aka Gert-Jan)
GT 2.0 JTS (2005)
Montreal 2.6V8 (1428700 - 1973/4)

Want to thank everyone for the replies. I've replaced the catalytic
converter, found it was bad and had to be replaced anyway. the sound
was still there, as for vibrations it would be more so from the seat.
with the top up and radio off it sound like it's from the rear center
of the car. there's a slight vibration but it gets worse at 40 mph and
75 mph.
the more I think about it, I'm thinking the guibo you mentioned. I've
had replace some hoses because they've dried out and leaked. with only
39k miles it hasn't been out much and I can see drying out. I'll check
it out.

Thanks again



alfistagj wrote:
> "Cableguy" > schreef in bericht
> oups.com...
> > Hello group, I was hoping someone might be able to help me out with
> > this one... I've got an 87 Alfa Romeo, 43k miles. last week when I was
> > driving home the car would vibrate a little and make a sound like I was
> > driving down the rumble strip (that gap on the right hand lane so you
> > don't go off the road when you fall asleep) or one of those 4x4 trucks
> > with large knobby tires going by. it only happens when I go over 75
> > mph. I tend to average 75-80 on my way home. hasn't been a problem yet.
> > it does the same thing once it warms up and I go about 40 mph in the
> > city. my thought was a possible problem with the catalytic converter,
> > there's some rattle sound from it when you try to move it. it's an
> > expensive part and I wanted to see if anyone else might of gone the
> > same road, sort of say...
> > Thanks for any help
> >
> > Regards
> >
>
> Is the sound speed or rev dependent?
> If it's rev dependent 'look for something in engine/gearbox area.
> If it's speed dependent look for something in driveshaft/rear axle
> My guess it's the so-called guibo, the rubber X-connection in the drive
> shaft and/or the intermediate bearing of the drive shaft.
> Dried out / old rubbers most likely; straight forward DIY job.
> --
> Ciao from The Netherlands
> alfistagj (aka Gert-Jan)
> GT 2.0 JTS (2005)
> Montreal 2.6V8 (1428700 - 1973/4)