Questions and Answers

Mercury Tracer Knocked Up Q. Vince, First off, awesome site! I am an avid DYI'er and this is just what I have been looking for! Now, the problem.... I have a rather odd knock coming from my car. It accelerates normally, then shifts; upon hitting the next gear sometimes (especially on warmer days) I will hear a ½ second to 1 second knocking coming from the engine.

And it only seems to happen when the engine hits just shy of 3,000 rpm around 2,800 I think) and does NOT happen from a standing start, only when the gear has shifting and the engine is recovering from the shift. Plenty of oopmh and no knocks at any other rpm (it even idles smooth and quiet once warm, by all accounts other than the knock a very healthy engine).

I can get the knock to stop either by driving through it (getting past 2800 rpm) or making it so the cars shift and drops below 2,800 rpm (how I usually drive, so as to prevent the car from knocking). Once I have started accelerating through its okay, except on the hottest days.

I have changed the fuel filter about three months ago and that seemed to help. I wonder if perhaps crap is clogging the filter or there is a more serious problem afoot. Any suggestions would be much appreciated.

Car:
1997 Mercury Tracer LS sedan
65,000 miles.
2.0 liter SOHC , well taken care of, oil changes etc.
Relatively new fuel filter, moderately new air filter.
No CEL or any other issues.

Thanks,
Chris

A. The knocking sound could be an indication of serious engine problems. A dull knocking sound indicates excessive clearance between the piston and cylinder wall, excessive clearance between the piston and piston pin or excessive clearance between the connecting rod bearings and the crankshaft. If the noise is more like the sound of a pencil tapping, then it is most likely a lifter or lifters. If it sounds like marbles in a tin can, then it is pinging.

I would have a mechanic give it a listen. He will be able to tell you which is which.