Trouble getting proper tension on serpentine belt + AC Clutch will not engage HELP!
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Joined: Jun 2021
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1991 W201 190E 2.6, 1991 W124 300E 2.5 TD
Trouble getting proper tension on serpentine belt + AC Clutch will not engage HELP!
I have a W201 2.6 auto. 232,000 miles. Great example of German engineering! I’ve owned this model for 4 years and outside of normal maintenance which I mostly perform my self I have had no real issues. However….I recently had the air pump bearing seize which resulted in shredding the serpentine drive belt. I obtained a slightly used air pump, ordered new multi-rib belt, new idler pulley, new tensioner w/adjusting bolt and nut and new tensioner shock.
Removal of old parts and installation of new was not difficult, but I noticed the old tensioner adjusting bolt/nut was slightly bent and threads stripped which I’m certain happened from the previous owner. Also want to make notation that prior to the rib belt shredding, the A/C worked properly. Now I am having an issue with getting proper tension on the rib belt and the A/C compressor clutch will not engage. I went through the process of loosening the main tensioner bolt and turned adjusting nut counter clockwise to tighten the rib belt but it just does not seem to be tight enough. Car starts with a belt squeal but disappears under acceleration. Now the A/C clutch will not engage. I will next check fuses and electrical diagnosis but I believe I may have a faulty tensioner as it just does not want to tighten to what I think is the proper tension. I have read numerous posts on the tensioner-adjusting bolt/nut but I am stuck. Can anyone on the forum help? Thanks in advance!!
Removal of old parts and installation of new was not difficult, but I noticed the old tensioner adjusting bolt/nut was slightly bent and threads stripped which I’m certain happened from the previous owner. Also want to make notation that prior to the rib belt shredding, the A/C worked properly. Now I am having an issue with getting proper tension on the rib belt and the A/C compressor clutch will not engage. I went through the process of loosening the main tensioner bolt and turned adjusting nut counter clockwise to tighten the rib belt but it just does not seem to be tight enough. Car starts with a belt squeal but disappears under acceleration. Now the A/C clutch will not engage. I will next check fuses and electrical diagnosis but I believe I may have a faulty tensioner as it just does not want to tighten to what I think is the proper tension. I have read numerous posts on the tensioner-adjusting bolt/nut but I am stuck. Can anyone on the forum help? Thanks in advance!!
Last edited by Deadbolt9009; Sep 4, 2023 at 11:28 AM.
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1991 190E 2.3
Are all of the new parts you purchased OEM or aftermarket? That can make a difference in them working properly for your car. These are great cars but they can become cranky when aftermarket parts not specifically made for the car are used.
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1991 190E 2.3
Your use of aftermarket parts is likely where your problem is. It's better to spend a little more and use OEM parts that'll last longer in the long term and they won't cause the issues you're now having.
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190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
It is likely that the aftermarket tensioner is the problem indeed. I can say the FEBI one is made in germany , good quality. OE is best of course.
Also you may have an installation issue as you have to insert it properly in the housing. I believe it is somewhat adjustable when it goes in before tensioning it.
You may have installed it improperly. I remember it being a bit tricky when I replaced mine 3-4 years ago. It was still the original on mine at 200+K miles and had very little life left in it.
Also you may have an installation issue as you have to insert it properly in the housing. I believe it is somewhat adjustable when it goes in before tensioning it.
You may have installed it improperly. I remember it being a bit tricky when I replaced mine 3-4 years ago. It was still the original on mine at 200+K miles and had very little life left in it.
Last edited by dolucasi; Sep 6, 2023 at 04:35 AM.
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1991 W201 190E 2.6, 1991 W124 300E 2.5 TD
It is likely that the aftermarket tensioner is the problem indeed. I can say the FEBI one is made in germany , good quality. OE is best of course.
Also you may have an installation issue as you have to insert it properly in the housing. I believe it is somewhat adjustable when it goes in before tensioning it.
You may have installed it improperly. I remember it being a bit tricky when I replaced mine 3-4 years ago. It was still the original on mine at 200+K miles and had very little life left in it.
Also you may have an installation issue as you have to insert it properly in the housing. I believe it is somewhat adjustable when it goes in before tensioning it.
You may have installed it improperly. I remember it being a bit tricky when I replaced mine 3-4 years ago. It was still the original on mine at 200+K miles and had very little life left in it.
I am curious as to your statement that I may have inserted, I assume, the tensioner improperly. I do not see any other way it can be installed. Unless you are describing the threaded tensioner rod/nut.
Please explain your statement as I will be doing a removal of the URO tensioner and installing the new parts today.
Thanks!
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1991 W201 190E 2.6, 1991 W124 300E 2.5 TD
I believe you have some merit in your comment and like I just replied to ‘dolucasi’ I am replacing the system today with a new FEBI tensioner and OEM adjusting rod. Thanks again!
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MBWorld Fanatic!
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From: SF Bay Area, CA
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
The plastic insert which is also a dial is separate from the housing, you need to put it together in the correct way so that the dial is showing you the correct tension.
This is what I meant. Otherwise you would not get the correct tension because the dial will be lying to you. The Febi one should work, mine was very well built.
This is what I meant. Otherwise you would not get the correct tension because the dial will be lying to you. The Febi one should work, mine was very well built.
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Thread Starter
Newbie
Joined: Jun 2021
Posts: 13
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1991 W201 190E 2.6, 1991 W124 300E 2.5 TD
The plastic insert which is also a dial is separate from the housing, you need to put it together in the correct way so that the dial is showing you the correct tension.
This is what I meant. Otherwise you would not get the correct tension because the dial will be lying to you. The Febi one should work, mine was very well built.
This is what I meant. Otherwise you would not get the correct tension because the dial will be lying to you. The Febi one should work, mine was very well built.
MBWorld Fanatic!
Joined: Mar 2016
Posts: 1,369
Likes: 195
From: SF Bay Area, CA
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
I am a continent and an ocean away from my car and home computer which may have contained some photo's I took.
Just remember that the dial moves in the counterclockwise direction as you tension it and you are trying to get it to the thickest part of that triangle in the dial.
So the thinnest part or the acute angled point is where you start, So zero tension should make the dial at the tip of that acute angle. This is my recollection.
Just remember that the dial moves in the counterclockwise direction as you tension it and you are trying to get it to the thickest part of that triangle in the dial.
So the thinnest part or the acute angled point is where you start, So zero tension should make the dial at the tip of that acute angle. This is my recollection.
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1990 190E 3.0
