Question about 2001 BMW 330

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BMW 318i M46 belt tensioning

How do you adjust tension on the serpentine belt driving the alternator?

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  • Kassie2 Sep 23, 2008

    Thanks! Also discovered it was spring loaded, but appreciate your response!

  • Anonymous Mar 21, 2014

    1993 belt replacement



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Adjust ur belt by following steps
now that you know where the components are these components are driven by a belt. So when you turn your AC on there’s a belt that’s driving the AC compressor, when you turn the stirring wheel and you have that nice that easy feel of turning the stirring wheel when you’re parallel parking your car that’s the power stirring pump doing its job. Your alternator is keeping the battery charged, the lights on and the engine running. So I want to show you where the belts are, what they look like, how to adjust them and how to tell a bad belt from a good belt. As you can see these are your drive belts, this is the AC drive belt it drives the AC compressor, this is the alternator drive belt it drives the alternator, if you look down here you can see this is where the adjustment is on that AC compressor belt, if you look right here this is the top adjusting bolt for adjusting the alternator either up or down to tighten or loosen the belt. There’s a bolt down here that locks the alternator in place and this bolt is the pivot bolt for the alternator. So if you’re going to let’s say remove your alternator belt you’d have to remove these covers, loosen this bolt, loosen this bolt that’s underneath this cover and adjust this bolt to either lower the alternator or raise the alternator, if you’re belt was too loose you’ll pull up on the alternator, if the belt was too tight you’ll

Posted on Sep 22, 2008


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The tensioner is spring loaded, and no adjustment is provided, or required.

But if for some, to me, unfathomable reason, the belt should become loose, causing slippage, I can think of only 3 possible causes:
1. Someone, unknowingly removed and replaced the belt incorrectly, by MISROUTING the belt on the pulleys.
2. Someone, unknowingly replaced the belt with one of the wrong size.
3. One of the belt driven components [water pump, alternator, smog air pump, power steering pump, air conditioning compressor, etc.] has been replaced with a new unit which has a different sized pulley than the one replaced.
4. The tensioning SPRING in the auto tensioning arm has become weak, and if so the arm assembly must be replaced.
As i said earlier, there is no provision for adjustment, as the tensioner arm assembly is supposed to automatically maintain the proper tension.

Thanx for using fixya.
Have a nice day.

Posted on Sep 22, 2008


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How do I replace the serpentine belt on a 1994 concorde?

Remove the alternator/power steering pump and water pump drive belt to gain access to the air conditioning drive belt.
To remove and install the air conditioning compressor drive belt, first loosen the tensioner pulley lock nut, then turn the adjusting screw to raise or lower the tensioner pulley assembly Accessory Drive - 3.3L Engine or Accessory Drive - 3.5L Engine To adjust the air conditioning drive belt, loosen the tensioner pulley nut and adjust belt tension by tightening adjusting screw. Torque pulley nut to 54 N•m (40 ft. lbs.) after adjustment.
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Changing a serpentine belt on an E36 BMW 318i(316i)

Remove the radiator cowling. It has 2 connecting clips(arrowed in photo)


Remove these clips by pushing out the centre portion with a small screwdriver as shown below.


Lift the cowlin up and remove. Be careful of pushing it against the radiator fins.
Locate the A/C tensioner pulley on the righthand side of the enginebetween the A/C compressor and Crankshaft, and pry off the dust cover(arrowed) with a screwdriver.


Loosen the 13mm nut inside and remove the belt.
Turn the 16mm bolt on the serpentine tensioner pulleycounter clockwise to slacken the belt and remove the belt. Refit the new belt to the routing diagram below and using the 1st track (closest to the engine) on the crankshaft
  1. Crankshaft
  2. Water pump/fan pulley
  3. Idler pulley
  4. Alternator
  5. Power steering
  6. Sepentine belt tensioner

If you are replacing the tensioner pulley remember that it is held in place by a reverse threaded bolt, so turn clockwise to loosen it.
Refit the A/C belt. fasten the tensioner pulley bolt by hand. Using a 10mm allen key in the hole in the pulley(arrowed), tension the belt, keep pressure on the allen key and fasten the pulley bolt with a wrench.
When refitting the fan shroud, position the shroud. It has a tab on each side halfway down the shroud that needs to locate in the radiator. Remove the centre pin from the shroud's clips completely. Insert the clip into its position and then insert the centre pin of the clip and push it in until flush with the clip itself.

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1 Answer


Belt Tensioner Operation:
00657_49214_belt_tensioner.jpgThis device functions as an idler pulley and is located on either the inside or outside of the accessory drive belt. Its provides the correct tension for initial belt adjustment and maintains this critical tension adjustment during vehicle operation. It can be found on conventional V-belts and the newer serpentine ribbed belts.

Jul 02, 2012 | Cars & Trucks

2 Answers

I am trying to hange the serpentine belt on my 09 lancer rallyart and it keeps slipping off

Locate the two belts on the left side (passenger side) of your Mitsubishi Lancer. The outer belt is a serpentine belt, operating four pulleys and the inner belt is your alternator belt.

  • 2 Follow the serpentine (outer) belt to the three pulleys lined up vertically near the front of the engine compartment. Locate the middle pulley, which is the tension pulley for the belt.
  • 3 Loosen the bolt on the middle pulley with a socket wrench by turning counter-clockwise. Do not remove the bolt, just turn it a couple of times. Loosen the tensioner bolt on the side of the of the pulley, facing the front of the vehicle.
  • 4 Remove the serpentine belt and then loosen the bolt on the alternator. With the alternator loose, move it forward so that the alternator belt loosens up and then remove belt from the pulleys.
  • 5 Install the new alternator belt by placing it over both inside pulleys. Tighten the tension on the alternator belt by moving the alternator back and keeping tension on it by holding it back with a long screwdriver. While the alternator belt is tight, use a socket wrench to tighten up the bolt on the alternator.
  • 6 Place the serpentine belt back on the pulleys and then use a socket wrench on the bolt on the front of the tension pulley. Once the serpentine belt is tight, tighten up the bolt in the middle of the tension pulley.
  • 7 Start the Mitsubishi Lancer's engine to test the alternator belt and make sure it is working properly. Once you have verified it is working, turn the engine off.
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    How do I replace the serpentine belt?

    1.8L Engine
    1. Using a belt tension gauge, measure the drive belt tension and compare with the following specifications:
      1. Alternator belt (new): 86-103 lbs. (383-461 N)
      2. Alternator belt (used): 68-86 lbs. (304-383 N)
      3. A/C compressor and power steering pump belt (new): 110-132 lbs (491-589 N)
      4. A/C compressor and power steering pump belt (used): 95-110 lbs. (422-491 N)


        Fig. Using a tension gauge to measure the alternator belt tension - 1.8L engines (click image for zoom)

    2. Using the deflection method, apply moderate pressure (about 22 lbs) halfway between the pulleys, and compare with the following specifications.
      1. Alternator belt (new): 0.31-0.35 in. (8-9mm)
      2. Alternator belt (used): 0.35-0.39 in. (9-10mm)
      3. A/C compressor and power steering pump belt (new): 0.31-0.35 in. (8-9mm)
      4. A/C compressor and power steering pump belt (used): 0.35-0.39 in. (9-10mm)
    3. If the specifications fall outside the ranges given, adjust the belt as follows:
      1. Loosen the alternator mounting bolt and adjusting bolt.
      2. Adjust the alternator to get the specified belt deflection.
      3. Tighten the bolts, then recheck the tension.


        Fig. Adjusting the alternator belt-1.8L engines

    Hope helps.

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    Loose serpentine belt. how do i tighten it?

    Try This:

    To install:
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    Jul 27, 2011 | 2005 Chevrolet Aveo

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    You don't adjust the tension. The tensioner on that serpentine belt is spring loaded and never needs adjustment.
    On a 2001 with normal miles (~125k), you should be on your second tensioner pulley and your third serpentine belt by now.

    May 11, 2011 | 2001 BMW 330

    2 Answers

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    ADJUSTING V-Belts Fig. 1: A gauge is recommended, but the belt deflection may be checked using light thumb pressure 85341063.gif
    Fig. 2: Loosening alternator pivot/adjustment bolt in order to tighten the belt 85341094.jpg Fig. 3: Apply tension to the belt being careful not to damage the case. While holding accessory in this position, tighten the pivot bolt. 85341095.jpg Fig. 4: Using a 1?2 in. ratchet, apply tension to the air conditioning belt while tightening the pivot bolt 85341096.jpg Belts are normally adjusted by loosening the bolts of the accessory being driven and moving that accessory on its pivot points until the proper tension is applied to the belt. The accessory is held in this position while the bolts are tightened. To determine proper belt tension, you can purchase a belt tension gauge or simply use the deflection method. To determine deflection, press inward on the belt at the mid-point of its longest straight run. The belt should deflect (move inward) 3?8 - 1?2 in. (10-13mm). A general rule for alternator belt tension is that the pulley should not be capable of being turned with hand pressure. Serpentine Belt On most newer vehicles, a single belt is used to drive all of the engine accessories formerly driven by multiple V-belts. The single belt is referred to as a serpentine belt. All the belt driven accessories are rigidly mounted with belt tension maintained by a spring loaded tensioner. Because of the belt tensioner, no adjustment is necessary. REMOVAL & INSTALLATION V-Belt Fig. 1: Loosen the component mounting and adjusting bolts slightly 85341064.gif
    Fig. 2: Remove the belt by pushing the component toward the engine 85341065.gif
    Fig. 3: Remove the drive belt 85341066.gif
    Fig. 4: To tighten the belt, pull the component away from the engine and tighten the mounting bolts to specifications 85341067.gif
    To remove a V-style drive belt, simply loosen the accessory being driven and move it on its pivot point to free the belt. Then, remove the belt. It is important to note that on engines with many driven accessories, several or all of the belts may have to be removed to get at the one to be replaced. Serpentine Belt Fig. 5: Serpentine belt tensioner - V6 engine 85341068.gif
    Fig. 6: Serpentine belt tensioner - V8 engine 85341069.gif
    A belt tensioner is used on these models, to maintain proper belt tension. To relieve belt tension, rotate the belt tensioner (using a 15mm socket) to relieve pressure on the belt. With tension relieved, the belt may then be removed from the engine. It is important to note the belt location at each pulley, to assure correct installation, and proper operation of the engine cooling system. A diagram may be helpful in denoting belt positioning. NOTE: Take care not to bend the tensioner when applying torque. Damage to the tensioner will occur. Maximum torque to load belt should not exceed 30 ft. lbs. (41 Nm). prev.gif next.gif

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    I have a '94 BMW 318i, the drive belt keeps falling off

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    Replacing serpentine drive belt on 1995 BMW 328i

    This just MIGHT help. I hope so.
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    Traditionally, the way this is adjusted is with a long threaded shaft like a screw, and on that shaft is a lock device to lock the adjustment of the adjusted accessory.
    Many times, it is the alternator that is adjustable.
    You would loosen the locking clamp, then turn the nuts on the threaded rod, and as you move the part (alternator, for example) towards the engine, the belt will loosen.
    Replace the belt and then tighten the nuts and tighten the lock.
    God bless your efforts.

    Oct 13, 2017 | 1995 BMW 3 Series

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