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  #1  
Old 07-19-2012, 06:16 PM
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horrible screeching sound front of engine 77 240D

my friends are having issues with their 240D. apparently its been making a horrible screeching sound off and on. bad enough they were almost afraid to drive it. i heard it only very very briefly the other night. literally for half a second. they dropped the car off so i could look at it today and i could only replicate it again for a split second. its coming from the front of the engine, i thought it might be the alternator belt but that seems fine?

i noticed on my 300D that i can spin the cooling fan freely, but on this 240D if i attempt that it is almost impossible to turn. in fact rotating the fan turns the entire pulley behind it, although not the belt. does that make sense? could something failing in the fan cause that noise? it seems louder than a belt.

the A/C is not connected/no belts there.

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Old 07-19-2012, 07:32 PM
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On a 240 there is no fan clutch so it will always turn the pulley. Perhaps the water pump is seazing up or did you check to see of the alternator belt is slipping? A slipping belt will make a hellofa racket.
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Old 07-19-2012, 07:40 PM
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yeah i had a suspicion it might be the water pump. i need to actually hear it happening.. which of course is frustrating when i cant get it to. i'll report back later. thanks!
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Old 07-19-2012, 08:16 PM
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77? Isn't there an idler pulley on there somewhere...on the A/C?
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Old 07-19-2012, 08:57 PM
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i just checked. yes. the AC has a double pulley, and there is an idler pully attached to a bracket above the fan. in the current setup the alternator is on the same belt as the water pump.
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Old 07-19-2012, 09:11 PM
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Quote:
Originally Posted by rs899 View Post
77? Isn't there an idler pulley on there somewhere...on the A/C?
Original post said AC was disconnected & no belt. Most likely cause is alternator belt slipping under load. That version has the York compressor & bracket above the alternator, makng checkng & servicing the alternator belt more difficult. The belt may seem OK but be slipping when first started or engine is revved. You'd need to remove that belt to verify if the waterpump or alternator is seizing/dragging. Also, The wear surface of the belt could be hardened/glazed. Otherwise, try to tighten it.

Happy Motoring, Mark
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Old 07-19-2012, 10:03 PM
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checked the belt... i can rotate it almost 180 degrees easily if i roll it between my fingers. also i can rotate the alternator by hand, something i cant do on my 300D. if i have to replace the belt on the 240D is that bracket going to be a huge hassle?
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  #8  
Old 07-19-2012, 10:17 PM
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Also check the main crank pulley. They have been known to fail.
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Old 07-20-2012, 02:46 AM
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Quote:
Originally Posted by sleepstar View Post
checked the belt... i can rotate it almost 180 degrees easily if i roll it between my fingers. also i can rotate the alternator by hand, something i cant do on my 300D. if i have to replace the belt on the 240D is that bracket going to be a huge hassle?
Sounds like the belt is very loose.
If it seems to be in OK condition, first try to tighten it. Ohewise, replace. Either way,the top-mounted AC setup makes it a hassle.

Happy Motoring, Mark

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