Name that screech?

#1 son's been patiently rebuilding his MX-5 after shunting it.

He's got it back running now but there's a ged-awful screech.

Really hard to tell from this
but any ideas?

It's been sat a while not running with no water (rad etc. had to be
replaced). My first thought is water pump but I'm really not sure.

Belts are not rubbing on anything according to him.

 

Oner of the drive belt idlers bent causing said noise. One of the bearings
fucked?

--


Nige,

BMW K1200S
Range Rover Vogue

 

Soundds like one of the anciliaries' bearings, as Nige says, or maybe
the belt itself is slipping.

How is the fan driven? If the rad was replaced and it's a mechanical
fan drive, does the fan foul the shroud?

Is the drive belt tight enough? If the battery's almost flat then the
alternator will load it substantially.

 

Mine has a bit of auxiliary drive belt squeal when very cold sometimes.
CBA to change it though I have a new one ready. It can wait until when
the cambelt is done in November (if it sails through the MoT). Nothing
like as bad as that.

Sounds a bit like a tensioner bearing or similar but water pump is the
most logical.

The change of pitch is noticeable after a while, but don't know how
significant it is.


--
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| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest * 2 Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+----------------------------------------------------------------+

 

Definitely not a belt, that's metal on metal - too bad for a bearing I
think, at least if it was OK before the work was done. Have you fitted
all spacers correctly, or bushes in mountings?, check for pulleys
rubbing on casings etc.

 

Yersh, he's going to try taking off the altenrator belt tomorrow. That
should eliminate a few things. Fan is leccy, so not that.

 

To me it sounds like a rubber screech.

Fan is electric on these.

 

Graphite powder will sort it.

Water pumps will probably be leaking at that point matey.

Nige,

BMW K1200S
Range Rover Vogue

 

I'd normally agree, but according to google, the bearings can make a
noise for quite a while before any leakage. Haven't actually checked for
leaking yet (pump's not easily visible).

 

When I first went to view mine at the dealers it made a very loud
screech from the auxiliary drive belt when they started it up, but it
disappeared very quickly.

The change in pitch on the video sound track is interesting. No change
of engine revs, but a sudden change in pitch to higher. That suggests
something suddenly turning at a higher rpm than before as it possibly
begins to free up. The only thing I can think of that could do that
would be a belt tensioner roller. Slipping on the belt when almost
seized up then starting to spin after a while but still slipping.

Simon's strategy of removing the auxiliary belt should certainly
eliminate some candidates.


--
+----------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest * 2 Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+----------------------------------------------------------------+

 

Interesting. Could be the cambelt tensioner I guess. At least the engine
should be ok on this car should the belt go.

I'm many miles away from the car at the moment so it's certainly a good
learning experience for him.

 

Remove the belts and see if the noise goes away. If so check all of
associated bearings for roughness and tightness. Be sure to tension
the belts correctly when refitting. A slipping belt can make a lot of
noise - spray some wd40 on the running belt and if the noise changes
or stops the belt is either loose or stuffed.

Listen for where the noise is coming from - clutch thrust bearings
are a common noise issue especially if incorrectly fitted.

 

That's a good way to **** up a perfectly good belt, though, and, as it's
a solvent, you don't really want it going anywhere near any bearings.

 

A few drops of washing up liquid lubes a belt enough to tell if it's a
squealer.

 

Unlikely - how do you think the garage mechanics make sure your car sounds
nice and quiet when it comes back from a service. Common practice in the
trade to spray a bit of wd40 on the belts.

 

Alternator bearing

 

Graphite powder on the belt to see if it's the belt

--


Nige,

BMW K1200S
Range Rover Vogue

 

WD40 is a lubricant. The belts are driven by friction. You think that
adding a lubricant here is common practise? I would have assumed they
used belt dressing.

 

Surprisingly, it is. It makes a rubbery belt stick to the driving
pulley, it seems - rather than making it slip round, which is the
obvious train of thought for the non-bodger. It is common practice,
certainly as a diagnostic aid in these days of cars with multiple
external drive belts, any of which could be slipping and screeching.

I used this effect to advantage on Elly's Clio, which picked up an
alternator drive belt screech one Autumn. The usual form, even for a
lazy **** like me, would be to whip out the weaponry and de-slack the
thing ... however, on consulting the Haynes BoL it commences the section
on belt adjustment with the timeless phrase "Raise the front of the car
and remove the front offside wheel". Then one should remove the
wheelarch splash panel by drilling out several rivets and only then does
the alternator become visible, hanging off the lower back of the
cylinder head, above the gearbox.

Then there's a transmission mounting to remove, an engine steady to
slacken and then lower the engine and 'box until the alternator finally
becomes accessible. Four or five hours, if you re-rivet the splash
panel.

Consulting the weather gods revealed low temperatures, rain, hail and
gusty winds. **** that for a game of soldiers, I though, wielding the
trusty aerosol of WD in the general direction until the squealing
stopped. A couple of re-applications got me through till April, by
which time an alternative approach had occurred - a couple of 1/4" drive
universal joints and a bent spanner, coupled with a socket ground down
to fit over the bolt head without fouling the suspension, and the job
was completed without raising the car and dropping the bloody engine.

A proper garage might have a can of belt dressing, but *every* garage
has a can of WD40 on the shelf.

 

<SNIP tale of French car ancillaries inaccessibility>

That's why the MX5 can wait until IGAMI to do the cam belt. Not as bad
as that TBF, but still requiring grovelling about underneath.

--
+----------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest * 2 Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+----------------------------------------------------------------+