knocking on a 1998 2.2 legacy

[sweetdang]

My car is knocking a lot when it is cold but once the car warms up the knocking sound is very low, barely noticable. I just recently changed by oil to 10w 40 with a bottle of the lucas oil stabilizer to thicken the oil but the sound is still there. Is my knock sensor dying? Any help would be appreciated.

[Reuben]

Just your tappets. Common subie problem.

 

Scratch that, Common subie feature is more accurate

[deadlydave]

Are you throwing a check engine light? If it is, get the code read and adjust your strategy accordingly. If you don't have a check engine light, your knock sensor is fine.

 

Does it sound like 'tick' 'tick' 'tick'? Do you still have full engine power?

[sweetdang]

still have engine power, no cels

[deadlydave]

It definitely just sounds like the typical subie tapping that happens when these cars age.

 

If it was actual knock, you'd notice perfomance loss. If the sensor was dying you'd get a CEL.

[Reuben]

Mmm, theres a big difference between a knock and a tap. About $4000 difference actually

 

IF the sound is a noisy engine when cold, it's a fearture of the SOHC 2.2L I had that engine and it did the same thing. You can fix it.. running ATF in the oil a week before your change it does the trick apparently. A thicker oil also helps.

[jrobyz]

I have the same kind of knocking with my 99 2.5 GT. It only knocks when it's cold, and is fine when it warms up. My oil level is perfectly ok and no warning lights are showing up. Is it something that's going to screw up my engine if I don't get it taken care of somehow? I don't mind the little annoyance of some knocking on the way to work on a cold morning, but if the thing is going to die on me b/c of it, I obviously want to take care of it. Thoughts?

[Turbo_Face]

I have this knocking when then car is cold as well, but not very often. When I got the car a year ago, it ran terrible, and the check engine light was always on, then I moved the knock sensor to a different part of the engine, and it ran a lot better.

 

Now whenever I get stuck in stop and go traffic, the CEL comes on, and the car runs like crap and knocks a lot more, and there is almost no power in 3rd gear. I can literally floor it and nothing happens. The light usually stays on for a few days and then goes away when I start it up, usually after the second or third day of driving it like that.

 

Also, I read that knocking can be caused by lower octane gasoline, so today I put in 89 octane instead of 87 and it ran a bit smoother. Any ideas on how to prevent whatever is causing the CEL from happening again? It's strange that it only happens in stop and go traffic...

[shtbxr22]

My vote is for piston slap! It will run for ages like that.......or you can replace the pistons/rings, and hone.

[Turbo_Face]

I just checked my car with Auterra Dyno-Scan software today, and found that it is the knock sensor that is causing the CEL in my car, so I plan to order one this weekend. Today the CEL came on for no reason, something to do with the hot weather, because it only came on during stop and go traffic in the winter.

 

shtbxr-how much does it cost to get the pistons and rings replaced, do you know? It sounds pretty expensive, so I hope that isn't what is causing the knocking in our cars!

[shtbxr22]

It's pretty damn expensive. unless you pay me to do it. it's ok, though because they will run forever like that. I'd wait until it makes the sound when fully warmed up, then do something about it.

[Stang70Fastback]

Yeah, had the same problem about 4 months ago. CEL came on and engine lost all power. Turned out the knock sensor was faulty.

 

I also suffer from the dreaded piston slap. It takes a few minutes on warm-up for it to go away completely. It's pretty loud and annoying, but hey - at least it runs! At 209,000 miles I can't complain.