OlliRock

Weird knocking/rattle sound from the back

10 posts in this topic

 Hi everyone,

 

I'm new in here. Here is my problem. I've got a weird intermittent knocking/rattle from the back left of the car. The sound seems to come from the belts but I've looked with my mechanic and all the belts system looks good. He's not very familiar with smart cars so he can identified where the sound come from.

 

Some of my friends that heard the sound told me that it might be the timing chain that is missing a tooth. If it's the case, is it something expensive to repair?

 

I will try to post the video of the sound but I'm only allowed to post 2mb.

 

Excuse my english, I'm more comfortable in french.

 

Thanks in advance.

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:welcome: to the club

 

If you post the video to YouTube and simply insert the link to that video here, it should be visible.

 

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I've been able to convert my video to a mp3. Anyway only the sound is important here and it fit under 2mb. So here the sound that my smart does.

 

Thanks in advance for your help.

VID_20161202_103629.mp3

Edited by OlliRock
Typo

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Suggest you remove oil filler cap and examine timing chain.  Turn engine over by hand and observe.  Try lifting chain with a pair of pliers.  Any slack beyond a mm lift means there is a problem.  Note that also oil chain drive could be bad.  It is pulley on oil pump that fails.  To confirm, remove oil filter and examine for metal particles.

 

Replacement of both timing chain and oil pump chain, both with sprockets, guides and tensioners is easy. Rear panels, rocker cover, oil sump, rear right engine mount and rear right wheel and wheel arch must come off to provide access.  Takes a good day.

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It is unwise to drive car if engine has faulty timing or oil pump chain drives.

 

Rattle can also come from exhaust heat shields.  Remove rear panels to check.

 

 

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No it seems to come behind the engine when I'm in front of the engine. The weird thing is that it intermittent but regular. Every few kilometers it start knocking and stop after few kilometers or if the car is idle, it start to knock every about 20-25 minutes... And the car (engine) is seems to run perfectly. There's is no impact on the driving, the power, nothing...

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So here is the answer. It is my alternatif doing this sound, and it Just died on me! I was supposed to change it tomorrow morning but it didn't wait...

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I was going to mention to check the Alt belt because I had one go on me like that. I heard a knocking from the rear on and off and it went away. It was the belt splitting on the sided.

 

Before I could check it pretty much let go. I had to have the car towed but I have CAA for that.

 

You have to grease bearings of the alternator in these little cars. Be careful not to get it on the belt. If you don't grease them they seize and die. Part of the weird servicing of this car. You'll get used to it.

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These alternators seize due to exposure to the elements causing rust..  Water and salt enter internals.  Rust forms in gap between stator and rotor.  Alternator is seized once rust has bridged gap.  Bearings may also seize but not common.  Greasing bearings can only be done by opening alternator and bearings out.  Very few do that but I did mine ten years ago.  Best remedy to avoid seizure is running engine weekly.

Edited by tolsen

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