what is that noise?

[eastwestboy]

Hello

 

I am brand new to this group and already have a question

 

I have a 97 Legacy 2.2L that has that banging noise. When I stand right beside the hood it sounds almost like a diesel. When I open the hood it seems to be something with the belt. I ran it without the outer belt, no change. I read a lot about piston slap and timing belt rattling and the belt tensioner. So at 128000 km I replaced the timing belt. I examined the tensioner, it looked like new and was in perfect condition, having lots of force and good hydraulic damping, so I didn't replace it with a new one. Still the same noise after the timing belt change. I then removed the two outer timing belt covers and let the motor run. The timing belt rolls perfectly, at least everywhere I could see with a flashlight. And the noise is still exactly the same as with the covers on. That makes me believe that nothing is wrong with the the timing belt and everything around there. The noise is most prominent when cold at idle and around 2500rpm. At around 4000rpm, it's never there. When warm, most of the time it's gone at idle and pretty lound between 1000 and 2000 rpm. But sometimes when warm the noise comes back at idle.

 

Do I have the piston slap? Impossible with a 2.2L?

 

Thanks for reading this. Yves

[Tolerance02]

Could it be the catalyst?

I Know it's not a common problem by Subaru but by other makes it is.

The ceramic block komes loose or is broken inside the exhaust (could happen if you ever hit a stone or something) and the exhaust pressure produce the banging sound in frequence of the engine revs.

This ceramic block warms up very fast and becomes very hot what may explane the differance by cold or hot engine.

Hit the exhaust with a rubber or plastic hammer could give the same sound.

 

Just a thought.

 

Urban.

[SevenSisters]

Have you checked your heat shields?

[1 Lucky Texan]

I've read that one indication of the tensioner being the problem is a 'rubbed' spot inside the cover. Sorry I never read specifically where. Might be worth double checking.

[nickb21]

There are one or two articles over at endwrench.com under archives, engine. One of them describes what Carl mentioned about the tensioner not pumping up properly when cold and allowing the timing belt to slap the plastic cover.

[eastwestboy]

Thanks for your answers. It sure has nothing to do with the exhaust pipes and the cat. The car and the wifes Impreza had both had the infamous heat shield rattle and I fixed both (Anybody interested how?). For the tensioner: When I had it out, I examined it very carefully and there was no wear at it or in that area. Also, the noise was no different when the side covers were on as when they were off. I am pretty sure it's coming from inside the engine.

Yves

[ScoobySchmitty]

Originally posted by eastwestboy

The car and the wifes Impreza had both had the infamous heat shield rattle and I fixed both (Anybody interested how?).

 

Oh Oh Oh! Does it involve a cutting torch and a blatant disregard for starting fires in tall grass??? Actually, I would like to hear how you cured the "redneck rattle".