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It sounds like a diesel

Recently, my 2000 Mercury Sable has started making a strange noise when I accelerate. It does not happen nearly all the time, but sometimes when I accelerate it makes a sound that sounds like a diesel engine. What could be causing this? Should I have it checked out?

The noise might be caused from a stretched timing chain hitting the side of the timing chain cover. This can be verified by removing the left valve cover. Bring the #1 piston to top dead center by turning the crankshaft by hand. While observing the valves for #1 cylinder, turn the crankshaft in the opposite direction by hand. If the crankshaft can be turned 6? or more before valve movement is observed, the timing chain requires replacement.


Agree; my Chevy V8 started to make that sound and sure enough it needed a new timing chain. Let a competent mechanic verify this of course. It cost me $300 10 years ago; you shoud budget for about twice that now.

It could also be something as simple as low oil. Have you checked the oil? Low oil level = low oil pressure = valvetrain noise.

Thanks for all the comments. My boyfriend was afraid that noise could be the transmission. I haven’t checked the oil since I had it changed about 6 weeks ago. I’ll check it this afternoon and see, but my guess is the oil is fine It has never had low oil before.

Another possible problem, your engine has an “anti-knock” sensor that controls ignition advance especially under acceleration…If it fails or is failing, it may leave the ignition too far advanced causing “spark knock” or detonation…Before you start throwing money at it, have a pro determine what the actual cause of the noise is…