So, as you may know, my 265K 2.2 in the Legacy shredded a bearing the other weekend on the way to Connie's Picnic. So I pulled a 130K mile 2.2 from the junkyard and finished up the install yesterday.

 

It started right up and it runs great :banana:

 

but.... there is a low moaning at idle. Using a stethoscope it seems to be coming from the passenger side/rear of the engine. It also continues and trails off for a second after the engine stops. I thoght I traced it to the Idle Air thingy, but I swapped the one from my old engine and it is still there...

 

Any ideas where else I should look??

 

I'm not sure if it matters, but while I had the engine out I also swapped the trans with the 4EAT that we used to have in the SVX Racer before we went to the 5-speed.

edit: The noise can barely be heard with the hood down, and not at all while driving. It seems to go away when going above idle, but that may be because the engine noise drowns it out.

hrmmmm

 

Since it goes on for a second after shutdown, i would rule out anything engine wise. Can it be something operated by vaccum that is making the noise?

 

It almost sounds like something is pressuring down.

 

nipper

Can it be something operated by vaccum that is making the noise?

 

That was my thought, I guess I could stick a vac gauge in the line somewhere...

 

How long should the system hold vaccum when the engine is shut off??

That was my thought, I guess I could stick a vac gauge in the line somewhere...

 

How long should the system hold vaccum when the engine is shut off??

 

It really depends. The power brake booster can hold it for weeks. The no-brake-pedal-in-cold is a stuck check valve. You can have a lazy vaccum isolater/delay/amplifier valve. They are little round things with a hose coming out of either end. Can be a minor vacum leak (get out the carb cleaner and spray around the noise). The leak may not be anywhere near the noise. If it drives fine, you may have to wait untill its a little more noticable.

 

Have you driven it in the rain with the replacement engine?

 

nipper

So, as you may know, my 265K 2.2 in the Legacy shredded a bearing the other weekend on the way to Connie's Picnic. So I pulled a 130K mile 2.2 from the junkyard and finished up the install yesterday.

 

It started right up and it runs great :banana:

 

but.... there is a low moaning at idle. Using a stethoscope it seems to be coming from the passenger side/rear of the engine. It also continues and trails off for a second after the engine stops. I thoght I traced it to the Idle Air thingy, but I swapped the one from my old engine and it is still there...

 

Any ideas where else I should look??

 

I'm not sure if it matters, but while I had the engine out I also swapped the trans with the 4EAT that we used to have in the SVX Racer before we went to the 5-speed.

edit: The noise can barely be heard with the hood down, and not at all while driving. It seems to go away when going above idle, but that may be because the engine noise drowns it out.

 

I wonder if it could be something related to the charcoal cannister/evaporative emissions system. Try taking the gas cap off while the car is running, then shut the car off...see if the noise is still present. (of course, this test could set a CEL.) The only other thing which holds a vaccum when the car is off is the brake booster (as nipper mentioned) and sometimes there's a check valve for the vaccum motors in the HVAC system (does Subaru even use vacuum motors? I don't think so.)

 

Nathan

I wonder if it could be something related to the charcoal cannister/evaporative emissions system. Try taking the gas cap off while the car is running, then shut the car off...see if the noise is still present. (of course, this test could set a CEL.) The only other thing which holds a vaccum when the car is off is the brake booster (as nipper mentioned) and sometimes there's a check valve for the vaccum motors in the HVAC system (does Subaru even use vacuum motors? I don't think so.)

 

Nathan

 

I wonder if the check valve in the brake booster is leaking. That would drain vac into the rest of the system. The brake booster makes a pretty big resivoir in that case.

 

nipper

any chance it's the abs system buzzing?

any chance it's the abs system buzzing?

 

Good thought, but no, definately not...

Maybe its just a zen thing

 

nipper

does it make it with the engine off? i know that sounds crazy, but i've heard the idle air jokers buzz and hum with the engine off, key on. swap them and they still do it....but otherwise everything runs and works fine.