2.2 engine knock

[allwheeldriving]

I recently bought a 99 legacy in the summer 2.2 single port. i have noticed that while driving at a certain rpm while on the gas (not coasting) there is a rattle, or fast knock also can be heard for a second or two on start up. I think it is either a sticky injector or bad valve lash? Just making this post to see if there's anyone out there that had a problem like this, any recalls or known faulty parts. looking for quick cheap diagnostic ideas dont want to go blindly replacing parts since im a broke student. also some history on the car 100k kilometers, seems to be maintained good i think an old couple owned it before, no mods done to it yet, unsure what rpm the knock is (no tach).

[grayguy]

It's a 2.2l, it's supposed to make noise, don't they all? Haha

[harrymaneuvers]

Rod Knock... I have your exact same car...


BAM!!!


http://www.sl-i.net/FORUM/viewtopic.php?f=11&t=21483


Looking back over the last 100k miles on the car, there might have been one or two times where the car might have run one or one and a half quarts low on oil that cause the rod knock...


It also could have been the one or two times driving, idling and even parking the car in EXTREME incline positions thinking that my car was a rock crawler.

[allwheeldriving]

Do you remember what was needed to fix it? I'm assuming rod knock is caused by excess gap in rid to crank bearing or rod to piston bearing(always heard the term never really asked or an explanation)? How bad is it to ignore that annoying little rattle?

[harrymaneuvers]

You are correct about what causes it... only reasonable fix I believe is a new short block.

I have had that exact sound for no less than 30k miles and it might be closer to 50k miles. I wouldnt be horribly concerned but it is something to watch. I dont hesitate to drive the car long distances. In fact, I have driven from Sacramento to Portland 3 times since July with no problems.

Put a magnetic drain plug in the oil pan and make sure you are looking for metal on each oil change.

[allwheeldriving]

Wait if it's caused by play in the bearing couldn't it be as simple as new crank bearings(if I'm lucky) or even new rods or crank? A new short block seems a bit excessive

[loganmossmusic]

You sure its not piston slap? That seems a lot more likely. I would assume rod knock wouldnt stop after a few seconds of warming up.

Piston slap: http://www.youtube.com/watch?v=p98AqJhH9Qs
Rod knock: http://www.youtube.com/watch?v=sik-OddhWzo

You can hear a distinct difference. Piston slap is light and not extremely noticeable, rod knock is hard to not notice.

Also new short block would be easiest, you dont know if metal shavings caused any damage anywhere else, as well as you could get new pistons which means better clearance and seal etc..

[allwheeldriving]

i always thought rod knock and piston slap to be the other way around (piston slap stops after cars warmed up, rod knock doesnt..) either way if either are not harming the engine and just being a nuisance im going to leave it for now and save that money for my engine swap fund:D