'03 Impreza annoying rattle when cold

[Fuzzy Logic]

I have an '03 Impreza TS wagon (non-turbo) and lately I'be been having an
annoying rattle at around 2000RPM after starting the car when cold (below
freezing). The rattle goes away after about 10-15 minutes. Any ideas what
this might be?

TIA

 

[Remco]

Not piston slap, I assume? I take it you can tell the difference, since
that usually goes away much quicker than 15 minutes.

I am not familiar with an 03 impreza, but my daughter's 93 impreza does
this as well and suspect Subaru hasn't fixed this problem yet (my old
GL did it as well

Check the heat shields mounted over the exaust -- they are notorious
for making rattling noises. I put a large hose clamp over it to stop
it, but on this group I've seen people jamb rocks between the muffler
and the heat shield.

Remco

 

[Fuzzy Logic]

Not piston slap, I assume? I take it you can tell the difference, since
that usually goes away much quicker than 15 minutes.

I am not familiar with an 03 impreza, but my daughter's 93 impreza does
this as well and suspect Subaru hasn't fixed this problem yet (my old
GL did it as well

Check the heat shields mounted over the exaust -- they are notorious
for making rattling noises. I put a large hose clamp over it to stop
it, but on this group I've seen people jamb rocks between the muffler
and the heat shield.

Remco

I suspected some kind of heat shield. The sound appears to come from the
engine compartment and is definitely a rattle and not piston slap. It's
intermittent and sometimes very loud. Hard to check by myself as it only
happens around 2000RPM and when the vehicle is cold and lasts 10-15 minutes
and then totally disappears.

 

[CompUser]

I suspected some kind of heat shield. The sound appears to come from the
engine compartment and is definitely a rattle and not piston slap. It's
intermittent and sometimes very loud. Hard to check by myself as it only
happens around 2000RPM and when the vehicle is cold and lasts 10-15 minutes
and then totally disappears.

Try tapping the various heatshields with engine
off, and cool. You got em on uppipe, downpipe,
a few places along exhaust, and on
headers...you'll have to pull your undercover off
to check them; they are probably the #1
culprit...seen a few posts here and NASIOC on
that.

Check shields for looseness, tap/whack with
something like a screwdriver handle, and you
should be able to find the one that makes "that
noise". Some of the fasteners may be loose or
rusted away...fixes might be new bolts, a hose
clamp around the whole affair, bailing wire,
etc...one fella put some self-tapping sheet metal
screws thru manifold shield, to brace it against
the manifold..whatever will work!

 

[Remco]

Yeah, that's a good way, definitely.

On my daughters, the heatshielf that you see right when you are looking
from under the front into the engine compartment was the culprit.
This particular one is two pieces, so I put a hoseclamp around it and
it went away.

Remco

 

[Danny Russell]

I have an '03 Impreza TS wagon (non-turbo) and lately I'be been having an
annoying rattle at around 2000RPM after starting the car when cold (below
freezing). The rattle goes away after about 10-15 minutes. Any ideas what
this might be?

TIA

In previous recent years of 2.5 II production, there was a TSB regarding the timing belt tensioner
(when cold) making a noise that mimicked piston slap. I don't know if that's still an issue or not,
but you might want to research that avenue. -Danny

 

[Clint Patterson]

I have the same vehicle and haven't had this happen, but it's only been
well below freezing a few days here.

 

[Remco]

I don't think it is so much temperature that causes this rattle. Ours
started doing it a couple of years ago in spring -- something just
likes to resonate and when things get loose, it gets worse.

 

[KaiC]

I bought a '02 TS wagon in Nov/04. There is a tapping noise upon gentle
acceleration after a cold start below freezing temperatures. I overheard
someone talking about such a problem being caused by the timing belt
tensioner, and that it was posted in some websites. I cannot find much on
the internet, and will appreciate any help in understanding the problem,
the potential consequences and the fix.
I did take the car to a dealer's service shop and had it parked overnight
there, but they did not notice anything unusual. I probably will have to
wait until next winter for some really cold weather to get the dealer's
shop to check it again.