HELP: Timing chain rattling on start up

[chasey]

Hi Guys
I just got my mazdaspeed 3 and its done a few km. upon start up there is a rattling noise which sounds like the timing chain.... it goes away after a couple of seconds but doesn't sound very healthy on start up. has any one else had this problem or can any one tell me what the fix is for it?

Thanks

 

[MSMS3]

It is most likely either (1) the variable valve timing actuator/timing chain stretch, which is the subject of a 7 year, 70,000 mile extended warranty, or (2) the accessory belt tensioner and/or related idler pulley. From what you describe I lean toward it being the accessory belt tensioner. That is a $35-50 US part and about a half hour of your time.

To check the timing chain you need to have the engine up to full operating temperature. I mean really warmed up. Drive it a while and then when you get home, unscrew the oil filler cap. The timing chain can be seen inside and can be felt with your finger. Try to press down on the chain and try to lift it up between your fingers. The tensioner should be holding it pretty tight. If it moves significantly doing this test, especially when trying to lift it up, chances are that you may have issue number 1 above. If you're in warranty, get the dealer to fix it, free.

If warranty is expired, expect a big bill, about $1200 according to accounts of others who have had to pay to get this done. It is NOT something you can fix yourself with a new tensioner and/or timing chain. You have to replace the crank pulley bolt, several washers and absolutely MUST have a special tool to reset the timing.

 

[chasey]

Thanks a lot MSM3 that's a huge help.... its not under warranty so lets hope its the tensioner

 

[MSMS3]

Listen carefully to the source of the sound too. It might not be coming from the valve cover. If it sounds like marbles rolling against each other and is coming from closer to the firewall on the passenger side it is the accessory belt tensioner and or idler pulley. There are Gates replacements for them through any auto parts store and an easy install.

 

[chasey]

when i rev the engine i can hear the chain rattling. I took it to a mechanic thats done a few of them and he said its some thing to do with the VVT that needs replacing and possibily the chain stretched a little