I'm curious to know what causes that trademark Subaru engine clatter, and how much is okay. I've heard that it's pistons, I've heard that it's valves...

 

My 2.2 in my '98 Impreza only does it when it's very cold, and the sound goes away when the engine is warm. I test drove an '02 Outback last week that was doing it on a 40 degree day. The seller told me that it's normal for a Subaru, but it seemed excessive.

Those darn short skirts!

My mom's 98 outback is louder than a diesel, doesn't quiet down that much when warm, and has been that way for the last 50k miles. Don't worry about it, even if it's bad, it won't affect how it runs.

Those darn short skirts!

 

this forum needs a like button for real!

My 2.2 in the 97 does it for about 15sec then it goes away. But it still taps for a while oh say 15 min of driving.

To the OP: If it is a steady tick-tick-tick-tick then it is likely from the lifters, very common and not really doing any significant damage but is kind of annoying. Models with hydraulic lifters will do it when they are oil starved (eg cold startup) or when they are plugged. I don't usually think of this as "clatter" though.

 

A "clatter" could be a lot of different things, including timing belt components, etc.

Subaru lesson #237

 

Piston slap.

 

In the good ol days pistons had long skirts. Cylinders are slightly wider at the bottom then the top. The piston skirts helped keep the pistons straight in the cylinder. More mass in thew piston meant more force to move it and a longer time for it to heat up.

 

In modern engines the skirt is almost gone. This allows for the piston to actually shift around in the cylinder and make noise. Once the piston warms up it expnads and the issue goes away. The mass is gone for quicker revving, better MPG and faster warmup.

 

All engines and compressors have some piston slap, some worse then others, and not all of it can be heard.

heh people always think I'm joking when I say that