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Discussion Starter #1 (Edited)
Engine rattling sound, cause and solution (Replace Drive Belt Auto Tensioner)

I saw from previous posts about possible causes of the rattling on the engine area. In my case this is how it sounds.


At first I thought the air conditioning compressor was going down since the rattling was really evident when the aircon turns on. But after looking at it more closely like removing the right front wheel and removing the side cover in the front right wheel well i found out where it was really coming from....it was the Drive Belt Auto Tensioner. Woohoo! a cheap part unlike replacing the compressor. This is the mechanism that automatically tightens the drive belt and keeping it in place. I actually had to use a newspaper and rolled it just to pin point where the rattling was coming from.

Anyway, replacing it is quite easy.
1. Remove the negative from the battery for safety purposes.
2. Remove the front rear tire and remove the plastic protective cover by using a screw driver. See 001_IMG_9200_Small.jpg & 002_IMG_9196_small.jpg.
3. Get a 15mm wrench and turn the bolt directly on the tensioner's pulley clockwise far enough for you to pry off the drive belt.
4. Get a 10mm wrench and remove the 2 screws that holds the tensioner in place on the engine. This should get the drive belt tensioner off. See 003_IMG_9194_small.jpg.
5. Get your new drive belt auto tensioner (Could range from $40-150 depending on where you get it.). Put it in place putting the 2 screws back. I did put a little bit of lubricant on the pulley just to make sure its all good.
6. Position your serpentine belt first and make sure it is aligned. See 004_IMG_9195_small.jpg & 005_IMG_9201_small.jpg.
7. Get your 15mm wrench and turn the pulley bolt clock wise and hold it. While holding it, put the drive belt back in place. (Normally this would be easier if you had an assistant helping you.) See 006_IMG_9202_small.jpg.
8. Thats pretty much it. After you place the battery cable back you can start your engine to test it....the noise should now be gone...well at least if your problem really is the drive belt auto tensioner. See 007_IMG_9203_small.jpg.After testing you can turn off and put back the plastic cover and your wheel.
 

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Thanks for the post, especially the step by step instructions. I have what (hopefully) may be the same problem on a 2003 Mazda 6. I went to a mechanic and after a few seconds he looked at it and said it was the air conditioning compressor - especially because it happens when the AC is engaged. I came here to see if there was another possibility. I'll give this a try.
 

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Discussion Starter #3 (Edited)
Yeah...at first i thought the same thing since it is really evident when the compressor turned on. Also by just looking at it from the hood you can't tell where it is really coming from. But the reason why it was really rattling is because with the compressor truning on, there is more load on the belt hence you get more vibrations on the tensioner. In my case it was the bearing of the tensioner pulley.

Anyway, good luck on your investigation...hopefully its the same thing since this one is waaaay cheaper than getting your compressor replaced.
 

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Raising the dead

After changing the oil and checking for leaks with the car in the air, i noticed my rattle is coming from the same area. Is there a issue with letting the rattle continuing for another 1500 miles? Moving at the and of the month with a 1000 drive
 

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I saw from previous posts about possible causes of the rattling on the engine area. In my case this is how it sounds.

YouTube - Mazda 6i 2003 - Drive Belt Auto Tensioner Noise

At first I thought the air conditioning compressor was going down since the rattling was really evident when the aircon turns on. But after looking at it more closely like removing the right front wheel and removing the side cover in the front right wheel well i found out where it was really coming from....it was the Drive Belt Auto Tensioner. Woohoo! a cheap part unlike replacing the compressor. This is the mechanism that automatically tightens the drive belt and keeping it in place. I actually had to use a newspaper and rolled it just to pin point where the rattling was coming from.

Anyway, replacing it is quite easy.
1. Remove the negative from the battery for safety purposes.
2. Remove the front rear tire and remove the plastic protective cover by using a screw driver. See 001_IMG_9200_Small.jpg & 002_IMG_9196_small.jpg.
3. Get a 15mm wrench and turn the bolt directly on the tensioner's pulley clockwise far enough for you to pry off the drive belt.
4. Get a 10mm wrench and remove the 2 screws that holds the tensioner in place on the engine. This should get the drive belt tensioner off. See 003_IMG_9194_small.jpg.
5. Get your new drive belt auto tensioner (Could range from $40-150 depending on where you get it.). Put it in place putting the 2 screws back. I did put a little bit of lubricant on the pulley just to make sure its all good.
6. Position your serpentine belt first and make sure it is aligned. See 004_IMG_9195_small.jpg & 005_IMG_9201_small.jpg.
7. Get your 15mm wrench and turn the pulley bolt clock wise and hold it. While holding it, put the drive belt back in place. (Normally this would be easier if you had an assistant helping you.) See 006_IMG_9202_small.jpg.
8. Thats pretty much it. After you place the battery cable back you can start your engine to test it....the noise should now be gone...well at least if your problem really is the drive belt auto tensioner. See 007_IMG_9203_small.jpg.After testing you can turn off and put back the plastic cover and your wheel.
Do you know the part number for these belt tensioners?
 

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Hi we have exactly the same problem, we took it in to get repaired and it was working great until we pulled into the drive. Now the noise is back again. But we have now lost our air conditioning. We took it back to the mechanic and he said our belt is slightly to big and the tensioner is hitting on something. He then said he doesn't know where the noise is coming from could be anything he said could pull the engine apart but it would be costly, be better just to buy a second hand engine. any thoughts on that?
 
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