What are the indication of of a bad belt tensioner?

i like to know if the tensioner itself can prevent the serpentine belt from being properly tightened. this has been loose for awhile now i found out, a new belt and shock did nothing. changed the adjusting rod, no change. the rod even stripped out when tightening it, so it has a new adj. rod now. the tensioner will move as you tighten it with the adjusting rod and it places tension on the belt, but the belt is still loose. yes, have a new corect belt. the problem did not start with a belt change. the old belt is still good.
one of my family members is working on it. i remember when i owned the car i was able to tighten it so it feels tight. NOW it deflects with VERY light finger pressure more then 1/2". it is loose. i don't see anything missing. it's threaded right. the car runs, but you can't use the A/C because the belt is too loose ans splashing water on it results in the belt coming off. so it's loose. i have adjusted many belts over the years ao i know that this is not right.
i don't know when this problem started. any ideas on this? it may have been after a waterpump change, but the same pulley was used. everything is original on the car. i wonder if a bad tensioner can prevent it from being adjusted properly? i am ordering a new tensioner.
thank you in advance.

Time for a new belt tensioner. Around $110 and a lot of pain to put it on. But is still a DIY.
Good luck.

__________________
New Addition to the family
2013 Passat TDI 5Miles
2004 E500 4MATIC Wagon 95k
1996 E300 Diesel 173k Sold
1993 300E 2.8 230k Sold
1994 E320 White Wagon 373K Sold
Still dreaming about ....500E


Radu Negru

If you're thinking of a new water pump, consider replacing it while the belt tensioner is out.

Sixto
95 S420
87 300SDL

Thank you. tensioner is the problem. once you have the radiator out it's easy.

I have an M104 engine and I was able to replace it whithout pulling the radiator. Also make sure the damper(little shock ) is ok and the tension adj is ok too. You may have damage it in your attempt to tighten the belt. see attached picture.

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__________________
New Addition to the family
2013 Passat TDI 5Miles
2004 E500 4MATIC Wagon 95k
1996 E300 Diesel 173k Sold
1993 300E 2.8 230k Sold
1994 E320 White Wagon 373K Sold
Still dreaming about ....500E


Radu Negru

These tensioners are a PITA. They are reverse threaded for some reason and soft as all hell. If you go past the throw they strip almost instantly. (This oughta make the purists shudder) I took mine apart, re-tapped the nut with a normal thread pattern and replaced the rod with a stock piece of threaded rod from the hardware store with an extra half inch on the end. (I ground the end that attaches to the cam with a bench grinder and drilled the correct size hole in it) Works perfectly.

I'll second the motion, they are a PITA. My PO had tried to tighten it without loosening the main bolt that the tensioner pivots on and the collar broke. Had to pull the whole thing off to replace the tensioner. The reason they have left hand threads is so that you can screw the nut "in" to tighten the belt.

OTOH, my daughter's Taurus has a very simple spring loaded tensioner, No rubber to deteriorate, no shock absorber, no pointer, just stick a wrench in a square hole & pull it away from the belt. Put a new belt on and release the wrench. Done.

Oh well,

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Norm in NJ
Next oil change at 230,000miles

That is the reson that a 3year old taurus cost around 3000 on ebay.
I the other hand this construction of the belt tensioner permit replacind the belt by hand whithout any tools. I always did this on all my cars(MB) and I have never change a tensioner because I did not damage them by trying to unscrew the tensioner allen bolt.

__________________
New Addition to the family
2013 Passat TDI 5Miles
2004 E500 4MATIC Wagon 95k
1996 E300 Diesel 173k Sold
1993 300E 2.8 230k Sold
1994 E320 White Wagon 373K Sold
Still dreaming about ....500E


Radu Negru