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      09-10-2013, 09:03 PM   #1
ZStig
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Hydraulic Tensioner short DIY

tips for replacing the hydraulic belt tensioner, difficulty is about 2.5 out of 5:

1. Remove the plastic cover above the radiator. Remove the plastic bumper undertray too that is under the radiator
2. Unplug the electric fan and remove it. There is a star shaped bolt on the bottom right, and top left corner. Then it pulls up, rubbing against some rubber hoses a bit.
3. Locate the ~2" diameter dust caps on the 2 pulleys, and remove them. One pulley is near the bottom, the hydraulic tensioner is near the middle of the setup
4. Draw the belt diagram for reference, to show how it is routed. Or find one online
5. In the middle of each pulley is a hole for a T50 star bit, which moves clockwise (I think; feel it out) on the pulleys to release pressure, use other hand to grab the belt and pull it off
6. Remove the smaller, air con belt first.
7. Remove the main belt
8. The pulley on the old hydraulic tensioner must be unscrewed while still on the car, to access the bottom screws to the hydraulic tensioner. T50 star bit, in counter-clockwise action.
9. Use 13mm socket to remove the 3 pictured bolts on the hydraulic tensioner. You may need an extension on your socket wrench for the bottom 2, of about 2 inches or so. The top one is easiest to take off with a 4 inch extension to protrude the tool past the metal frame
10. Carefully record which bolt goes where, so you can install them correctly on the new one.


11. Install new hydraulic tensioner by lining up the holes and feeling the top bolt in. I believe it is screwing into an aluminium oil filter housing which is expensive to replace, so don't OVER tighten it.
12. Re-install the old pulley on the new hydraulic tensioner. A new pulley is preferred though.
13. Re-install the main belt first, and the AC belt second.
14. Put everything back together

Attached is a picture of a new hydraulic tensioner, with the pulley removed. You can see where the three 13mm bolts are!
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      09-11-2013, 12:09 AM   #2
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Thanks!!
Tensioners and idlers are on my 100k mile list, coming up soon.
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      09-11-2013, 01:50 PM   #3
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What were the wear symptoms, or is this a 100k preventive maintenance item?
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      09-11-2013, 03:01 PM   #4
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For me it's just 100k PM. Do a forum search.
Some have reported the bearings going out and squeaking/rattling.
If the tensioner wimps out, you'll get belt slippage.
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      09-11-2013, 03:36 PM   #5
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A supercharged car is much more sensitive to belt slack. Symptom was lower boost.

My original one went at 65k miles, spectacularly crashing into my water pump pulley while ripping out a piece of the oil filter housing. I replaced it last year, but I think I got a defective one because the tension wasn't strong with the same size belt. It is about 50% better on the fresh tensioner. I can still twist the belt past 90* with my hands, but that would be cured with a smaller belt.

Honestly the most intimidating part is removing the belts, if you've never done it before
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      10-19-2013, 10:05 AM   #6
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my hydraulic tensioner pulley is sitting at an angle now and destroyed 1.5 belts. I find myself re-reading this thread. lol
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      10-14-2014, 12:26 PM   #7
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Probably will change out my 7 year old belts (48,000 miles). Are our pulleys and hydraulic tensioner strictly a mileage based wear item or will age also affect their replacement schedule?
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      10-14-2014, 11:01 PM   #8
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Quote:
Originally Posted by elerner61 View Post
Probably will change out my 7 year old belts (48,000 miles). Are our pulleys and hydraulic tensioner strictly a mileage based wear item or will age also affect their replacement schedule?
I don't think its a wear item at 48k miles. My supercharger puts extra strain on it, and the older model yea E85 M's have an oil filter housing that is poorly designed. One of the bolts from the hydraulic tensioner screws into a "floating" mounting point. A replacement filter housing I got has that part fully welded.
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      10-27-2014, 09:57 AM   #9
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Changed my belts this weekend (AC compressor belt was very cracked at 7yrs, 48Kmiles). Discovered my alternator tensioner pulley sounds like an old skateboard wheel, so going to go back in and change that pulley and the diverter pulley as well.

Has anyone got quick access to TIS and the torque specs for when I install those two pulleys?

Thanks.
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