Knocking noise comes and goes Topic is solved

jacie431 · Post by **jacie431** » 11 Feb 2016, 22:39

I have a 2002 volvo v70 wagon 2.4 5cyl. 206,xxx miles. I just bought this car used. Checked it all out. Seemed like a great deal I could not pass up. Drove it home. Drove all over town. Was loving it. Got next to a drive through. And heard a loud knocking echoing off the wall. Or I would say more like sticking a playing card into a fan. Or a bicycle spoke. The noise went away after a minute. Drove the car home and put it in park. And the noise came back. Checked the oil. About a quart low. Topped it off. The noise seemed to be gone. After running for about 5 or 6 minutes it returned. A steady knocking noise. Like a card in a fan almost. listened all around the motor. And isolated the noise to be coming from back side of the motor close to the fire wall. And it is loudest near the exhaust manifold. And close to the gaurds over the timing belt. I checked for any loose items. Removed the top of the cover, and inspected the timing belt. It seems in very good shape. The previous owner claims it was changed recently. It looks good. I searched forums and this seems to be a common problem. But no forums have any resolution on what it is. I am so confused. And if this is common some one must know what is happening. The knocking comes and goes. When it is not present the car is a dream. But when it is happening I have a sickening feeling in my stomach. Please help. I am a single woman. And this was all the money I had purchasing this car.

Post by **abscate** » 12 Feb 2016, 05:52

Welcome Jacie!

It could be an exhaust manifold leak, although the coming and going is not indicative of that.

You might be able to isolate the location better with a short piece of hose used as a stethoscope

There are some solenoids on the top of the engine that can make noise when they fail.

We do not want a timing belt failure on this car...that would ruin your new ride.

Take a peek in the Help wanted forum to see if we have one of our regulars nearby to help diagnose this.

Post by **oragex** » 12 Feb 2016, 06:21

If you can record a video and upload it on Youtube it may help us coming with ideas. How does the rubber in the upper-rear engine mount appear to be? It's the large mount on top drivers side of the engine. At which frequency the noise seems to appear? Does it happen when driving in the morning while the engine is still cold?

Post by **vtl** » 12 Feb 2016, 10:59

Remove top plastic cover sitting over t-belt area (two torx bolts and two clips on sides), disconnect VVT solenoid and see if it helps.

Also most likely the engine is just worn too much, worn lifter tapping or generally engine has low oil pressure.

What oil did you use? Should be w40 at minimum, you can also try w50.

Post by **oragex** » 12 Feb 2016, 15:06

Another possibility would be a rattle from the exhaust heat shield either behind the engine or near the catalyst underneath the car. Carefully, it is hot to the touch.

: engine ratle.jpg (42.17 KiB) Viewed 9955 times

jacie431 · Post by **jacie431** » 12 Feb 2016, 15:58

I will check the solenoid next. It does not seem to a loose shield. Its consistent. With a steady striking sound. And it can even be just loud enough to hear it. Or it can be very loud. It slowly gets louder as it is happening. And it is completely random. The oil I used was 10w 30. I do plan to change the oil next. And was considering sea foam? My brother in law suggested it. I can tell you it never does this on start up. And seems to not happen while I am driving. I did notice a slight flux in the idol last night as it was happening. Nothing serious.

jacie431 · Post by **jacie431** » 12 Feb 2016, 16:44

Here is a video. It is hard to hear over the valve noise. But when I put the camera down behind the timimg chains you can really hear it. And when I take the camera inside the car. You can hear it. It was hard to get capture it. I had to start the car. And just wait for the noise. It took about eight minutes. And then it started doing it. Off and on.

Post by **abscate** » 12 Feb 2016, 17:03

It is at idle only, disappears when revved. It also takes few seconds to come back from idle.

Ugh. Im thinking rod knock or big end bearing knock but the behavior on revving isn't right.

jacie431 · Post by **jacie431** » 12 Feb 2016, 17:29

It honestly sounds different in person. On the camera it is drown out. I compare it to holding a playing card in a fan. And is very close to the pulleys and timing belt. On the back side of the motor. I will try to get a better video. Tomorrow. And move around the back side. It is just confusing. Im not a mechanic. But doesn't an engine knock. Stay pretty constant? And get worse when you rev it?

jacie431 · Post by **jacie431** » 12 Feb 2016, 17:38

Hmmm tensioner? Or pulley bearing? I personally dont have the tools or any idea how to inspect further. I have found this issue all over you tube. And they all go cold. Nobody has said what is the cause. And this is a very nice car. I hope to save it. Or maybe I can just drive it like this?