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Lately I noticed a slight ticking noise when pulling off calmly (from a stop light, for example) at the exact moment the car starts moving. Happens when the engine is still cool, before I hit the highway, don't seem to notice it after that.

I've never heard an actual detonation so it's hard to tell if the sound is that or simply the rubber mounts or something (weather is currently cold and there is creaking in the suspension when driving over speedbumps). I might have some vacuum leaks. Is it possible for the engine to detonate while still cool at a regular slow pull-off?

  • If you're not sure that it's detonation, you might not want to use that word in the title - it might get people thinking in the wrong direction. What about just saying "clicking sound"? – Nate Eldredge Oct 27 '15 at 14:17
  • Hopefully it's more understandable now. – I have no idea what I'm doing Oct 30 '15 at 9:54
  • Edited the title as well :-) – Rory Alsop Oct 30 '15 at 11:11
  • Could you post up a video or sound bite? Else there are so many possibilities... – Zaid Oct 30 '15 at 11:12
  • I highly doubt that the sound will be audible if I simply recorded it from inside the car. I could try, but it's a very subtle one. – I have no idea what I'm doing Oct 30 '15 at 11:23
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I'm not going to say it's NOT detonation, but given the symptoms it sounds more like you have a mechanical issue. Ticking, COULD be a lifter, it could be a rod bearing, an alternator pulley.... I think you get the point. The best thing you can do is determine if the noise occurs under load or not. Rev the engine while observing the engine bay, if you have an electronic throttle, have someone do it for you while listening for noises. You need to determine if it's coming from the top or bottom of the engine, this can be achieved with an automotive stethoscope (A screw driver works too). What is the year make and model of the vehicle?

You could have an issue with detonation, but theres also 100 other things that can make noise while accelerating. It's also important to know what type of car it is and the age, as detonation is a premature or combined "Detonation" of combustion components. It's also referred to as "Spark Knock"...

  • It's not happening when the car is stationary. I've heard that high load at low RPM increases the chance of detonation, and that is exactly what happens at pull off. It's not a clunking suspension sound, it's a quite subtle irregular series of ticks. Doesn't even always happen, but when it does - always at the same time. It's a 1999 Volvo V40 1.9 Turbo. – I have no idea what I'm doing Oct 30 '15 at 10:05
  • Well, by now I am quite convinced it is the suspension rubber creaking. Completely disappears when weather is warmer and is louder and faster when starting more aggresively. – I have no idea what I'm doing Nov 18 '15 at 11:42
  • This ticking could possibly be your CV axle joint ripped open. They tend to make a ticking noise when turning or when accelerating. If the grease is heated up the sound is a little more subtle. You can also test your suspension by using your knee to repetitively move the vehicle up and down, and back and forth while in park or with your parking brake one. – cloudnyn3 Nov 18 '15 at 18:21
  • I know that noise well, that's not it, more subtle. I'm thinking dry rubber contacting metal parts in cold weather. – I have no idea what I'm doing Nov 19 '15 at 7:34
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    3M makes a paste which is excellent for any rubber or plastic application. It's also great for brakes as well. The part number is 08946. Spray will work, but paste tends to last much longer than spray. – cloudnyn3 Nov 19 '15 at 14:16

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