Harmonic balancer


New Member
So my girlfriend bought a 95 Mustang convertible. It had one minor problem, consisting of a zero to sixty time in the thirty-second range. My initial diagnosis was bad cats, bolstered by the fact that the floor got hot enough to fry an egg and the cats would glow taillight red. Well, new cats helped a little but I could still mat the throttle in my driveway and still be doing less than 10mph when I reached the street.

Google to the rescue. Searches revealed many people with the same problem with the 3.8 engine, several of them on this forum, and at least half a dozen claimed a new harmonic balancer fixed the problem yet none of them explained exactly how the balancer was affecting the performance. All they said was it was "bad," "worn out," and the most descriptive said the balancer "sh*t the bed." Having never owned a Mustang, other than my grandmothers '66, I was unfamiliar with the particulars of sh*tting the bed. I checked the timing and it was definitely retarded, like 50 degrees or so, which would certainly make it sluggish. I speculated that perhaps the outer ring slipped, which would cause vibration, which might be bad enough that the knock sensor picked it up and retarded the timing. I could't think of anything else so I pulled the balancer.

Turns out the outer ring hadn't slipped. The freaking woodruff key busted out the side of the groove. I have seen keys shear, but never do this. I can only conclude that the OEM balancer is made out of metal with the consistency of cheese. A new balancer fixed the issue, and it now accelerates normally.