Outback sounds like a diesel

[ploutos]

My 99 outback with 120k miles has, for the last 50k or so, sounded like
a diesel. My mechanic said he was pretty sure it was the shims in the
cylindars (I may be getting this wrong now) and that to fix it was a
lot of work and results far from guaranteed. He says no damage is
being done and I can live with the noise, but it is irritating and
anyone riding in my car tends to wonder what is going on.

Any ideas what to do?

 

[Edward Hayes]

Could be piston slap if it diminishes as it warms up.

 

[marcus153]

From what I can gather, older Subaru engines do tend to have a normal
"ticking" sound.

You might try running on premium fuel for a while, perhaps three
tanksfull, and see if that helps (reduces engine "knock").

Marc Sindell
Twin City Subaru Sales
Montpelier Vermont

 

[ploutos]

It often, though not always, does go away after it is warned up. What
does piston slap mean?

 

[Edward Hayes]

Piston slap is caused by a slight increase in the piston to piston
bore clearance. If it goes away when full warm then probably not a
problem. When under the 5/60,000 mile warranty Subaru does not
consider it a problem IF it goes away after warm-up.

 

[l.lichtman]

If it goes away after the engine warms up. it is DEFINITELY not fuel
related preignition knock. IOW, running premium fuel won't help.

 

[Fuzzy Logic]

It often, though not always, does go away after it is warned up. What
does piston slap mean?

I had a similar noise that went away when the car warmed up. Turned out to
be the belt tensioner. Fixed under warranty '03 Impreza TS.

 

[CompUser]

@g43g2000cwa.googlegroups.com>,
(e-mail address removed) says...

If it goes away after the engine warms up. it is DEFINITELY not fuel
related preignition knock. IOW, running premium fuel won't help.

If the engine continues running, it's NOT
preignition, period.

 

[Danny Russell]

My 99 outback with 120k miles has, for the last 50k or so, sounded like
a diesel. My mechanic said he was pretty sure it was the shims in the
cylindars (I may be getting this wrong now) and that to fix it was a
lot of work and results far from guaranteed. He says no damage is
being done and I can live with the noise, but it is irritating and
anyone riding in my car tends to wonder what is going on.

Any ideas what to do?

Don't fight it man, just go with it. Driving a diesel car puts you in class above those in mere
petrol autos. Just ask anyone from Birmingham, Michigan. :^) -Danny