High-pitched whine from somehere in the engine...

MUNDANEATROCITY

MEMBER
2000 DODGE DAKOTA
2.5L
4 CYL
2WD
MANUAL
125,000 MILES

After about five minutes of engine run-time, a high-pitched whine will start to emanate from the engine. The noise seems to respond to engine load; it will occur at idle, and when I take off it will briefly pitch down, as if it was responding to the increased load on the engine. However, it isn't regular -- it might stop altogether, and then re-appear, sometimes for just a second or two, or it will stop completely. There doesn't seem to be a predictable pattern, other than the five minute thing. The engine seems to operate exactly as it always does.

I'm thinking maybe it's a pulley or belt tensioner, perhaps. Could it be a vacuum leak, as some have suggested? I'm pretty much at a loss here.

4 Replies

HMAC300

MECHANIC
48,601 POSTS

Belt and tensioner replacement is recommended at 60k take the belt off and run engine see if it down' the same thing if not it's a accessory problem.

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Thursday, May 8th, 2014 AT 3:56 PM

MUNDANEATROCITY

MEMBER
4 POSTS

I replaced both tensioner pulleys and the belt (I even tried the shorter belt, bypassing the AC compressor), with no change. In fact, the whining squeal (for lack of a better term) is louder than ever.

Also: I've noticed that the noise is more insistent, more strident, after the truck is first started in the morning, when the ambient temperature is lower, after being parked overnight. After shutting off the engine for a few minutes and re-starting, the noise disappears, only to re-appear after a few minutes. Later in the day, after the ambient temperature rises, the noise becomes rather erratic and unpredictable, and will even stop occasionally, only to reappear later.

With no "check engine" light and no other indication of a problem, I'm at a complete loss.