Odd noise

#1

The 156 1.9 JTD had started making a very odd noise.

Started yesterday, under heavy throttle, a sort of
shhhshhsshshs noise, best I can describe it is like the
noise of waves receding on a pebble beach.

Only happens under heavy throttle, neutral or slight
acceleration there is no problem.

So, how terminal and expensive is this likely to be?

--
Rob Pearson
156 1.9jtd sportwagon (now)
164 V6 Lusso (gone)

#2

R C Nesbit wrote:

Quote:

The 156 1.9 JTD had started making a very odd noise.

Started yesterday, under heavy throttle, a sort of
shhhshhsshshs noise, best I can describe it is like the
noise of waves receding on a pebble beach.

Only happens under heavy throttle, neutral or slight
acceleration there is no problem.

Stationary or moving?

Quote:

So, how terminal and expensive is this likely to be?

Probably neither. Sounds like a possible air leak. Had a listen under
the bonnet?
Also, try turning the aircon *right* off.
--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
116 Giulietta 3.0l Sprint 1.7 145 2.0 Cloverleaf 156 V6 2.5 S2
Triumph Sprint ST 1050: It's blue, see.
www.cuore-sportivo.co.uk

#3

On Fri, 14 Aug 2009 09:52:20 +0100, Catman
<catman (AT) rustcuore-sportivo (DOT) co.uk> wrote:

Quote:

Also, try turning the aircon *right* off.

That *should* turn off on full throttle anyway. I agree that the
description suggests a high pressure air leak.

I'm guessing, as I haven't looked at this on that engine, but there
should be flexible (rubber?) hoses between the turbo and intercooler
and intercooler and inlet manifold. The joints are usually well fitted
by Alfa so I'd suspect a split pipe.

--
Z
Scotland
Alfa Romeo 156 2.4JTD Veloce Leather
'Oil' be seeing you..
(Email must have the word 'Alfa' in the
subject line to get through auto-filtering)

#4

R C Nesbit wrote:

Quote:

It does sound like an air leak though. I shall try to investigate
further over the weekend.

My 2.4jtd (currently on ebay

) had a split in the inlet pipe and made
a sound similar to what you describe under hard acceleration.

I cured it temporarily with duct tape.

HTH

AndyB

#5

Zathras wrote:

Quote:

On Fri, 14 Aug 2009 09:52:20 +0100, Catman
catman (AT) rustcuore-sportivo (DOT) co.uk> wrote:

Also, try turning the aircon *right* off.

That *should* turn off on full throttle anyway. I agree that the
description suggests a high pressure air leak.

Should it? Blimey? Is that just full, or FULL hard in the mat?

Quote:

I'm guessing, as I haven't looked at this on that engine, but there
should be flexible (rubber?) hoses between the turbo and intercooler
and intercooler and inlet manifold. The joints are usually well fitted
by Alfa so I'd suspect a split pipe.

There'd be a potential power loss as well?

--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
116 Giulietta 3.0l Sprint 1.7 145 2.0 Cloverleaf 156 V6 2.5 S2
Triumph Sprint ST 1050: It's blue, see.
www.cuore-sportivo.co.uk

#6

Sunbeam spoke:

Quote:

My 2.4jtd (currently on ebay

) had a split in the inlet pipe and made
a sound similar to what you describe under hard acceleration.

I cured it temporarily with duct tape.

It got worse on the way home tonight, and the engine warning light came on
at one point. Then it lost power.....
Pulled over, had a look around, could see nothing, re-started it, engine
light off, but the SHSHSHSHSHHS changed, when it was there, I had power,
then it would drop off, and so would the power.

Limped it home, and with the aid of #1 son, we found a split in the bottom
hose - nora clue what it is, but it is a large (100mm diameter?) soft
rubber hose at the bottom front of the engine, from mid-way towards
near-side wing.

There is a definite split in it, and you can see it open when the engine is
revved.

Tomorrow I shall clean off the greasy black gunk it is coated with and
apply some duct tape as a temporary bodge. If that fixes it, then I can
just order one.

--
Rob Pearson
156 1.9jtd sportwagon (now)
164 V6 Lusso (gone)

#7

R C Nesbit wrote:

Quote:

Sunbeam spoke:
My 2.4jtd (currently on ebay

) had a split in the inlet pipe and made
a sound similar to what you describe under hard acceleration.

I cured it temporarily with duct tape.

It got worse on the way home tonight, and the engine warning light came on
at one point. Then it lost power.....
Pulled over, had a look around, could see nothing, re-started it, engine
light off, but the SHSHSHSHSHHS changed, when it was there, I had power,
then it would drop off, and so would the power.

Limped it home, and with the aid of #1 son, we found a split in the bottom
hose - nora clue what it is, but it is a large (100mm diameter?) soft
rubber hose at the bottom front of the engine, from mid-way towards
near-side wing.

There is a definite split in it, and you can see it open when the engine is
revved.

Tomorrow I shall clean off the greasy black gunk it is coated with and
apply some duct tape as a temporary bodge. If that fixes it, then I can
just order one.

Sounds like an inlet to me. IIRC the inlet is lower left innit?

--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
116 Giulietta 3.0l Sprint 1.7 145 2.0 Cloverleaf 156 V6 2.5 S2
Triumph Sprint ST 1050: It's blue, see.
www.cuore-sportivo.co.uk

#8

Catman wrote:

Quote:

R C Nesbit wrote:

Limped it home, and with the aid of #1 son, we found a split in the
bottom hose - nora clue what it is, but it is a large (100mm
diameter?) soft rubber hose at the bottom front of the engine, from
mid-way towards near-side wing.

There is a definite split in it, and you can see it open when the
engine is revved.

Tomorrow I shall clean off the greasy black gunk it is coated with and
apply some duct tape as a temporary bodge. If that fixes it, then I
can just order one.

Sounds like an inlet to me. IIRC the inlet is lower left innit?

That's the one!

AndyB

#9

On Fri, 14 Aug 2009 18:27:35 +0100, Catman
<catman (AT) rustcuore-sportivo (DOT) co.uk> wrote:

Quote:

Zathras wrote:
On Fri, 14 Aug 2009 09:52:20 +0100, Catman
catman (AT) rustcuore-sportivo (DOT) co.uk> wrote:

Also, try turning the aircon *right* off.

That *should* turn off on full throttle anyway. I agree that the
description suggests a high pressure air leak.

Should it? Blimey? Is that just full, or FULL hard in the mat?

Yep. It was part of a cunning plan to deliver *full* engine power for
overtaking. I could never tell myself but it the compressor is
disengaged on, as you say, FULL hard on the mat! Alfas are loaded with
cunning plans..

--
Z
Scotland
Alfa Romeo 156 2.4JTD Veloce Leather
'Oil' be seeing you..
(Email must have the word 'Alfa' in the
subject line to get through auto-filtering)

#10

On Fri, 14 Aug 2009 12:56:11 +0100, R C Nesbit <spam (AT) ukrm (DOT) net> wrote:

Quote:

Yes, but under no load the noise only comes in at high revs, so is
competing with the engine noise.

The reason for that is that it's a clever variable venturi turbo. This
allows the ecu to control boost pressure depending on engine speed and
load rather than just due to exhaust pressure (to a certain degree).
Just revving the engine won't put much load on so the turbo won't get
to deliver its maximum charge.

If you go flat on the accelerator, the rule book is often thrown away
by car engines and they will care little for perfect fuel/air ratios
and emissions. They'll just attempt to max out as best they can.

--
Z
Scotland
Alfa Romeo 156 2.4JTD Veloce Leather
'Oil' be seeing you..
(Email must have the word 'Alfa' in the
subject line to get through auto-filtering)