99 GMC Safari Under Hood Engine Loud Noise

DCGRISWOLD

MEMBER
1999 GMC SAFARI

99 GMC Safari v6 3.0 Automatic. Replaced engine recently with a reconditioned unit. Unknown mileage.

While at idle and especially when driving, there is a loud noise that seems to come from the left front, drivers side, under the hood. It is like a vacuum cleaner type sound.

I took it back to the shop that installed the engine and they said it may be alternator noise. The car seems to be running fine, but it sounds like a beast.

Any help trying to locate the noise would be appreciated. Could it be exhaust manifold crack. Would that effect performance. Could it be the alternator.

My original engine that had a main bearing failure at 160,000 never made this sound. It is annoying.

So, what can I do to find the source of the noise and if none can be found, is there a way to deaden or damper it. Thanks, I gave you a donation. Dan Cox

1 Reply

PEAR69

MECHANIC
1,482 POSTS

Ok Dan, first--It is most likely not a cracked exaust manifold. If this were cracked the noise would sound like a single engined prop plane and your engine would run very bad. It may be your alternators' bearing going bad or something of that nature. Here is an easy way to check. Your engine has s serpentine belt on it. Find the belt tention pully and take the tention off the belt. I believe a 3/8 ratchet will fit in the square hole to do this. Now spin the alternator and everything else that will spin with the tention off the belt. Listen for any worn out bearings on all the pullys, alternator, powersteering pump, ac compressor--etc.