Back in for piston slap

S

SchnauzerDad

Well, the Forester is back at the dealer overnight, so they can start it
cold and hear the piston slap or whatever the noise is. Naturally after 2
months of daily noise, it didn't do it this morning, but maybe the dealer
will be lucky. I had quite a go-round with Subaru about authorizing a loaner
car for me.
To make sure they hear the noise, I videotaped a cold start and provided
them with the tape. Funny thing is the Service manager's conversations with
Subaru resulted in a regional Subaru rep. requesting permission to hear the
car start as well. So, we will see!!
chas
 
The sound could be the fuel injectors. Some cars have loud injectors when
the engine is cold.
 
WELL GANG! THEY HEARD IT!!!
I spoke to the service writer and he told me the Subaru regional rep
actually heard the car make a cold start racket, and they are putting in a
new timing belt tensioner tomorrow. Lets see if it works.
Chas
 
SchnauzerDad a écrit :
WELL GANG! THEY HEARD IT!!!
I spoke to the service writer and he told me the Subaru regional rep
actually heard the car make a cold start racket, and they are putting in a
new timing belt tensioner tomorrow. Lets see if it works.

I've been reading a lot of stuff off the Subaru
technical website and came across the following,
out of the Subaru Service / Technical
Support Line Newsletter TechTIPS JAN/FEB 2003


-- begin quote :

SUBJECT: ENGINE NOISE WHEN COLD

(Note: This is a re-release of past articles.)

We wanted to review some of the past information on
engine noise.

The 2000MY and current models, with the 2.2 and 2.5
engines were made more fuel efficient, more powerful,
and had a flatter, more usable torque curve than in
previous years. To achieve these objectives, it was
necessary to make improvements and modifications to
the Subaru engine lineup. The following are some
of those improvements:

1. Mechanical valve lash adjusters (reduces friction)
2. Lightweight pistons (reduces inertia)
3. Short skirt, Molybdenum coated pistons (reduces friction)
4. Increased compression ratio (improved power output)
5. Improved cylinder head design (improved cooling)
6. Improved induction system (improved breathing)

As a result of these enhancements, some engines may
exhibit some engine noise during the warm-up period
after a cold start-up. This noise is a consequence of
the engine improvements and is not, in any way, an
indication of any engine problem.

A light engine knock, after cold start, that gradually
dissipates as the engine warms up and is virtually
undetectable (from inside the vehicle) once the engine
has reached operating temperature, is a normal
characteristic of these engines. Repair attempts to
reduce this type noise are generally unsuccessful.

If you have a vehicle in which an engine noise is
other than that as described above, be sure to take
the time to check all possible causes prior to
condemning the internal components of the engine.

Before replacing parts in an attempt to eliminate
engine noise, the engine should be inspected externally
and internally for another source of noise. A look
at the engine oil is a good place to start. New
engines will have a small amount of metal particles
in them, but after that should be relatively free of
metal.

Another area to look at would be the timing belt
tensioner and the belt and sprockets. There have
been cases where noises coming from under the belt
covers and from external components sound like a
deep internal knock.

If a customer complains of a cold engine knock,
and the cause is from the improvements listed
above, please reassure him/her that no permanent
engine damage will occur. If the noise persists
and is still clearly audible when the engine is
warm, please consult your DSOM.

-- end quote.
 
Hi,

I went through a similar episode with my '02 Outback Wagon. Round and round
with the dealer. We ended up leaving the car there overnight so they could
hear the noise.

They kept the car for two weeks. The final diagnosis was :

bad timing chain tensioner. Turns out the tensioner is hydraulic. The
original had air in it. When the engine was cold the timing chain slapped
making a ridiculously loud noise. Sounded to me like dreaded piston slap.

Well, when the engine would warm up the air in the timing chain tensioner
would expand, the timing chain would get tighter, then the slapping sound
would go away.

After they returned the car to us (18k miles ago) I haven't heard the noise
once.

Maybe you should ask them to investigate that possibility.

Good Luck,

Roy
 
Paul Pedersen said:
I've been reading a lot of stuff off the Subaru technical website
and came across the following, out of the Subaru Service / Technical
Support Line Newsletter TechTIPS JAN/FEB 2003

Paul, thanks so much for pointing this out. It reassures me that my
dealer isn't making crap up. I hear this slight knock on startup
too...and am hereby assured it's normal.

Makes me think that they may have replaced 2 timing belt tensioners on
this car unnecessarily though.
 
Well Roy, seems like they heard it, cause it's sitting at the dealer waiting
for the new tensioner. My noise was not a 'light knock' as described in the
factory info. I hope I have similar results.
Chas
 
Paul said:
I've been reading a lot of stuff off the Subaru
technical website and came across the following,
out of the Subaru Service / Technical
Support Line Newsletter TechTIPS JAN/FEB 2003

-- begin quote :

SUBJECT: ENGINE NOISE WHEN COLD

(Note: This is a re-release of past articles.)

We wanted to review some of the past information on
engine noise.

The 2000MY and current models, with the 2.2 and 2.5
engines were made more fuel efficient, more powerful,
and had a flatter, more usable torque curve than in
previous years. To achieve these objectives, it was
necessary to make improvements and modifications to
the Subaru engine lineup. The following are some
of those improvements:

1. Mechanical valve lash adjusters (reduces friction)
2. Lightweight pistons (reduces inertia)
3. Short skirt, Molybdenum coated pistons (reduces friction)
4. Increased compression ratio (improved power output)
5. Improved cylinder head design (improved cooling)
6. Improved induction system (improved breathing)

As a result of these enhancements, some engines may
exhibit some engine noise during the warm-up period
after a cold start-up. This noise is a consequence of
the engine improvements and is not, in any way, an
indication of any engine problem.

A light engine knock, after cold start, that gradually
dissipates as the engine warms up and is virtually
undetectable (from inside the vehicle) once the engine
has reached operating temperature, is a normal
characteristic of these engines. Repair attempts to
reduce this type noise are generally unsuccessful.

If you have a vehicle in which an engine noise is
other than that as described above, be sure to take
the time to check all possible causes prior to
condemning the internal components of the engine.

Before replacing parts in an attempt to eliminate
engine noise, the engine should be inspected externally
and internally for another source of noise. A look
at the engine oil is a good place to start. New
engines will have a small amount of metal particles
in them, but after that should be relatively free of
metal.

Another area to look at would be the timing belt
tensioner and the belt and sprockets. There have
been cases where noises coming from under the belt
covers and from external components sound like a
deep internal knock.

If a customer complains of a cold engine knock,
and the cause is from the improvements listed
above, please reassure him/her that no permanent
engine damage will occur. If the noise persists
and is still clearly audible when the engine is
warm, please consult your DSOM.

-- end quote.

Wow! I thinks that's called "spin". In engineering design, when you
put too much emphasis on improving one parameter and in so doing have
compromised another parameter to the point that it becomes a problem
(and in the automotive business, a perceived problem is a problem no
matter how hard marketing tries to convince the public it is not a
problem), it's time to back off on the parameter that has been
over-emphasised and bring the overall design back in balance. The proof
will come when future designs will not be plagued by the problems that
they've created in the existing design.

Hasn't someone posted in the past that Subaru has fixed piston slap by
replacing the pistons with ones of an alternate design (i.e., longer
skirts maybe)?

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")
 
Wow lucky you . Ihave been fighting with my dealer for the past 2
years about my cold engine noise . Mine was diagnosis with piston slap
.. Subaru gave me a TSB from them saying that some engine noise is
normal and as long as the noise goes away when the engine is warm,and
they will do nothing about it .
I also have the time belt noise but the last 2 times I left my car
overnight it didn't make the noise . I did a lot of complaning about
the piston slap noise .
So the DSR from Subaru said he could probable get Subaru to autherize
a short block but it may not help .Which I didn't have done . While
he was there we went out and started 5 different subaru's and 3 of
them had the knockning noise, and one of them was the H6 engine . He
offered me a 100k 7year Subaru gold warranty plan free . So I have
atleast some peice of mind for now . I am going to do a oil analysis
at my next o/f change to see if there is any metal in the oil . I do
have to say that the car burns no oil between changes . I have a 02
outback base wagon 4eat with 31k miles on it . My only problem with
the car is the piston slap noise .

Mike k
 

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