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Diagnosis: Howling Noise from Engine

2833 Views 2 Replies 3 Participants Last post by  Bosnian Discovery
Hi folks! I need some assistance on an issue that my husband and I cannot diagnose. I own a Land Rover Discovery II year 2001. The howling noise began when I would reach speeds of 50 mph and only upon acceleration. It would stop I let of the acceleration. Then the noise began happening any time I was accelling. As soon as I let off the gas it would stop. Lately the noise is pretty much happening all the time even when I let off the gas. When I am idling there is NO noise so it is almost impossible to diagnose. Clearly the problem had gotten worse because I hear howling almost ALL the time now. Anyone have similar issues or ideas of what to trouble shoot? It definitely sounds like it's coming from the engine. :)
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we would probably need more of a description of "howling" metal on metal or wind type howling.
my first thought would be a failing clutch on the cooling fan as a first option, they tend to lock on acceleration and then release when not under pressure but they need to be fairly shot and you should be able to wobble the fan and feel movement. when mine went I had an intermittent roaring sound and a slight vibration when I got above about 50mph. All went away with a new water pump and fan clutch.
More than likely it's coming from your drivetrain.

Not to scare you, but you might have a failing differential or transfer case, neither of which is a good thing. Check the fluid level and condition in both diffs and the TC and replace with high quality synthetic as necessary. If the fluid level was low or if you see metal shavings in the drained fluid you could have done some serious damage.

It could also be a failing front driveshaft. When failing they tend to emit a noise under load. Typically it's a "clicking" or "chirping" noise but I wouldn't rule out "howling" either. Inspect it quickly - if it is the driveshaft making noise then catastrophic failure is right around the corner. If it breaks at speed it could (will) punch a hole in your transmission.

There is the outside chance that it's coming from the engine, likely from a failed bearing on one of the accessories or pulleys. Pull the fan, pull the belt, and then spin the alternator, compressor, steering pump, water pump, tensioner, and idler pulleys by hand. If you feel resistance or hear a grinding it's likely that it could be the source of your howl.
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