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Discussion Starter #1
My 2005 Smart engine has started making a scraping noise that increases with engine speed. Sounds like maybe timing chain has a bad spot on it or something. Almost sounds like a faint hacksaw sound. Anyone know of any problems that might be lurking causing this sound.
 

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Try to isolating the sound by disconnecting the belts and see if the noise goes away. The idler pulley sometimes will make the scraping noise when it goes bad.
If it makes a rattle noise sometimes the muffler breaks apart inside.

Leroy
 

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Discussion Starter #3
This is a definate scratching sound....(sounds like a fingernails on a washboard) it has me scared ..I had read somewhere about timing chain sliders breaking, and oil pump sprocket failures. But.. Can't find info on this anymore....real conserned...this noise is getting louder.
 

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How many miles are on your car? From some reading I have done on the Canadian and Euro forums, timing chain has to be adjusted or replaced at a certain mileage.
 

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Discussion Starter #5
My car only has 17,000 miles on it.......I haven't heard of any adjustment of timing chain.....one person said it sounds like a rear brake was dragging and scraping.....but had to stop and rev motor to let him hear same sound....he was puzzled too....
 

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If you are in a cold weather area, the plastic chain tensioners (there is one for the oil pump and one for the camshaft) can crack and stop working. I would suspect this. Catastrophic engine failure can happen if that's what it is.

My diesel has 110,000 miles and is on the original chains and tensioners. But I am considering having the chains and tensioners changed in 2011. My car makes no unusual noises.
 

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Discussion Starter #9
Ok...noise is for sure coming from the timing chain area. Removed belts, and noise still was there, so rules out that. Now what can be wrong?? looked in oil filler cap, even with engine running, All looks ok.......Dumped oil on timing chain with it running, did not change noise. Maybe oil pump chain? Shame, this car only has 16,000 miles. Engine used to be very quiet. Real worried now...Should I worry...or just drive it till it quits?
 

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I'm definitely no expert on the 450, but I have done my fair share of engine work. If the sound is coming from the timing chain area, I think you've found your problem. Only recourse now is to pull the cover off and inspect the damage. I definitely wouldn't drive it if it's getting worse. Fix it now, and you may save the engine, wait until it quits, and you'll more than likely be replacing an engine.....

Just my 2 cents worth....
 

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If you removed all the belts and the noise is still there it is time to take a look at the timing chain and oil pump chain. There are lots of plastic parts that can go bad under the timing cover. The cover can be removed with the engine in the car but it is a pain in the but to do. If you keep driving the timing could jump time when the chain goes which causes lot of damage. On the diesel cars when the oil pump chain goes it takes out the timing chain and can cause the rocker arms to break and damage the valve which in turn can brake the valve.

Leroy
 

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Discussion Starter #12
Ok... need repair manual...or instructions on how to get timing cover off....do I need to take cylinder head off.? Where can I get instructions?
 

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Ok... need repair manual...or instructions on how to get timing cover off....do I need to take cylinder head off.? Where can I get instructions?

I have access to the MB WIS system, I can look for the info tonight when I get home. I see your is an '05, I'm assuming 700cc gas? If I can access it, I'll send you a PM and we can discuss how to get the info to you.
 

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To remove the timing cover you have to remove the valve cover to get to the two bolts that hold the cover on. If you do not remove the head you would have to pry the cover off. So when you put it back on it would leak on the top where the head gasket is at. You also have to remove the oil pan. Plus if your going to replace the timing chain there are lots of plastic parts that need to be replace and the head would have to come off anyway. Simple steps, remove engine, remove head, remove oil pan, remove timing cover. And a lot of things in between.

Parts needed; timing chain kit, head gasket and seals, head bolts.

Leroy
 

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Discussion Starter #16
Oh, sorry...I got the info you sent me.....thankyou very much....... I really hate the thought of trying to fix this...Really upset :mad:....and I don't even know if there is <really> anything wrong. The timing chain looks real tiny, but in good shape, and tight..... The noise is there...someone told me that aluminum engines always make a lot of valve chain noise. They didn't hear any odd noise... now I wonder , do I tare this motor apart to find nothing really wrong....or just drive it...or sell or trade it? I'm not sure what to do....for now ..I drive it with my fingers crossed listening for any change in the noise. As far as getting parts and doing the work its gonna be a pain in the but......:(
 

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I realise this is an old thread... but did the OP get to the bottom of what was causing the noise because I have the same symptoms coming from my Roadster!
 

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I realise this is an old thread... but did the OP get to the bottom of what was causing the noise because I have the same symptoms coming from my Roadster!
Since rayman1946's post was made 5 years ago (1/14/2011) perhaps you could send him a PM to see if he found "the cause" or has moved on?

Fact, you are basically sitting under the hood with THE ENGINE in a plastic car, you will hear all variety of noises. Absent, a CEL or codes being thrown just drive the car . . .
 
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