Little nocking sound question

[Johnny]

Hello, i bought an 1999 Impreza at 128,000 km in exellent condition but i
have a little question, when the engine is cold i hear a little nocking
sound that come from the center of the engine (well i think so). 5 or 8
minutes and it's gone, i'm not familiar with 4 cylinders sound so should i
have to worry? The engine is a 2.2 and it take's no oil at all.

Thank you

Johnny

 

[Carl 1 Lucky Texan]

A mechanic could pin this down for you but known issues that may relate
to the noise you hear are TB tensioner and piston slap (but maybe that's
the 2.5l?)

Carl
1 Lucky Texan

 

[AM]

piston slap (but maybe that's the 2.5l?)

My 98 2.2 had bad piston slap.

 

[Johnny]

But when the engine is hot it sounds very smooth.

 

[Stu Hedith]

I had a '98 GT sedan that exibited the exact behavior you describe. It
improved when i switched to synthetic 5W30, ESPECIALLY in winter. I
talked to my dealer about it one time out of curiosity. The service
manager gave me a photocopy of some sort of training info for the
mechanics i believe that described the design of the valve lifters and
the noise is normal. Based on my experience with the oil, I'm guessing
the oil passages to the lifters is quite small and colder (more viscous)
oil can't make it there very well.

Stu

 

[Johnny]

Can an anti-drainback oil filter can help? Since years my cars is on syn
oil.

 

[Verbs Under My Gel]

Can an anti-drainback oil filter can help? Since years my cars is on syn
oil.

Nope. The filter sits vertically, with the open side _up_, so there's
no need for an anti-drainback valve.

 

[Mike B.]

Just wrote that my '01 Outback 2.5 is getting the TB tensioner replaced. Bad
TAP when cold (30 degrees or so) under warranty at 51K. Thought it was a valve
tap.