I'm trying to replace the alternator on a '95 Mercedes Benz C280 but I can't find the tensioner to loosen the serpentine belt. The Attached image has the alternator in yellow and the serpentine belt in purple. Anyone knows where this is located?
[This message has been edited by FierociousGT (edited 01-30-2008).]
It's located just below this pulley. It's the pully that has the belt spinning 180 degrees around it on the back side of the belt. Some are spring loaded, some are screwed tight. I can't see the adjustment screw on your picture, so I think it's just spring loaded, but I'm not totally sure. I forget when they stopped using the screw type and started using the spring loaded one. You may have to remove the fan and fan shroud in order to get to it.
The 104 engines never had a spring tensioner. There will be a bolt you need to loosen in between the water pump pulley and p/s pulley....after the fan and fan shroud have been removed. There is a special tool to remove the fan (8mm allen on a long bar & holding fixture for the fan clutch) You will need to remove the fan to access the alternator. Once the bolt has been loosened, there is a 13mm adjusting screw to release the tensioner. Pull on the belt as you turn the screw counter-clockwise. Dave
------------------ 1987 GT (my toy-see above), 1987 GT (wife's toy), 1986 SE soon to be VR6, certified master technician/shop owner www.njautobahn.com
Originally posted by Patrick: Slightly off topic, but what program did you use to add the color tint to your images? Great idea for clarifying objects in the photo.
If that is a 6mm allen, it doesn't need to come out. The tensioner bolt will be either a 19mm hex head or 10mm allen (those are the two MB uses for the tensioner bolt). The 13mm tensioning rod will be behind the water pump and power steering pump. Take the fan shroud off first. Then remove the fan (8mm allen in center of fan clutch-right hand thread-lefty loosey). Once the fan is out you will have enough room to fit a small elephant into the engine compartment and still get at the tensioner. Then loosen the middle tensioner bolt (the 10mm allen or 19mm hex). DO NOT loosen the threaded 13mm tensioning rod until you loosen the tensioner bolt or you will break the rod and have to replace it. It is behind the tensioner, so more time is involved. I'll see if I can post a picture of the removal procedure from my manuals Dave
Originally posted by bmwguru: Once the bolt has been loosened, there is a 13mm adjusting screw to release the tensioner. Pull on the belt as you turn the screw counter-clockwise. Dave
Dave, where is this 13mm screw located?
Thx
EDIT Damn, I just missed your post... lol
[This message has been edited by FierociousGT (edited 02-02-2008).]
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08:26 PM
bmwguru Member
Posts: 4692 From: Howell, NJ USA Registered: Sep 2006
Taking a closer look at the picture I think you may have a late 1995 or 1996 C280. I'd need the VIN to be sure, but if that is the case....there is no tensioning rod or 19mm/10mm allen. Instead, still remove the fan and then the tensioner IS spring loaded. This is only if it is a late 95 or later. Most 1995 C280's have the threaded rod. Dave
I have to take over from here, Dave is obviously having a senior moment.....well maybe longer than a moment..
Anyway, the engine that you are working on replacing the alternator in has the belt tensioner WITHOUT the tensioning rod. Take the fan shroud off, remove the fan, remove bmwguru's elephant, the tensioner IS spring loaded. Once the belt has been removed, there are only 2 bolts left to remove the alternator.
Joey (Dave's wife)
P.S. Don't forget to disconnect the battery, check the OVP, and I'll send you a bill for my input
Actually, I'm going to beg to differ. We just happened to have a 95 C280 in the shop two days ago and it made me think of this thread. So I decided to look, and sure enough, the tensioner is not spring loaded, it had the adjusting rod behind the thermostat. But you are right though, elephants have no business being in the engine compartment!
Having a hard time getting to the fan for removal. I had to cut off part of an allen wrench due to the spacing between the radiator and fan. Don't seem to be 8mm allen bolt. Can some one confirm this?
[This message has been edited by FierociousGT (edited 02-03-2008).]
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06:50 AM
bmwguru Member
Posts: 4692 From: Howell, NJ USA Registered: Sep 2006
Actually, I'm going to beg to differ. We just happened to have a 95 C280 in the shop two days ago and it made me think of this thread. So I decided to look, and sure enough, the tensioner is not spring loaded, it had the adjusting rod behind the thermostat. But you are right though, elephants have no business being in the engine compartment!
My wife looked up the VIN in our catalog and it shows that it is a late 95. That would make it spring loaded. The more common Mercedes tensioner has the threaded rod...started on the 103 engines back in 1986. I guess they realized it was a bad design because you would break the rod if you didn't know about the hidden tensioner bolt. It pays 3.5 hours to change the rod...and every DIYer would come in and put it on my desk and say "I give up. Just fix this" Anyway, on a C280 there isn't a lot of room to work, but once the fan comes out it is much better. The Newer 112 engine 210 chassis E-class, you can fit two elephants once the fan is out. The fan clutch bolt is 8mm. They get rounded off pretty easily. Normally, I can get them off when they are rounded, but worst case the radiator will have to be removed and you can pop it free with an air chisel. You'll need a new fan clutch at that point. I think the special tool is $50.00 It might be worth investing in it if you own the car. The fan comes off for a lot of repairs. Dave
hehehe I got the bloody alternator out! Did NOT have to remove the fan. Had to pull and jam the springed tensioner with a crow bar and unscrew a coolant hose that ran into the block. I'm going to head out to pick the replacement alternator. I post if I have any questions.
Thanks again to everyone for all your help....
What an elephant?
[This message has been edited by FierociousGT (edited 02-03-2008).]
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11:54 AM
bmwguru Member
Posts: 4692 From: Howell, NJ USA Registered: Sep 2006
It is a lot easier with the fan out. I have done it a few times with the fan in, but only because the fan clutch bolt was badly stripped. It is a real pain in the ass that way, but if you are accustomed to working on Jap cars, it won't be that bad. I'm spoiled by the German cars. Normally, I don't remove any coolant hoses. You must have meant the small heater hose sized water pump hose. Glad you got it out. Make sure to get the correct alternator. Check the OVP. Mercedes don't like being jump started. There is a relay near the battery with one or two fuses on the top under a plastic cover. That is the Over Voltage Protection relay OVP. If any of the fuses are blown, throw the relay out and get a new one. Replacing the fuse does not fix it. If the relay is bad, you will get all kinds of weird issues. Dave ps...all that wet dirt around the center of the fan is a sign that the fan clutch needs replacement.
[This message has been edited by bmwguru (edited 02-03-2008).]
Dave, This Mercedes had a French Valero alternator and the new one is a Duralast (Remfg Bosch) will I run into issues?
Valeo is ok. They make a lot of Radiators and alternators for the German cars. Bosch is the brand I would use. BMW is the only one where is would need to be Valeo or Bosch specific. You'll be fine. Just make sure everything matches up. Dave
Valeo is ok. They make a lot of Radiators and alternators for the German cars. Bosch is the brand I would use. BMW is the only one where is would need to be Valeo or Bosch specific. You'll be fine. Just make sure everything matches up. Dave
Many of the newer MB's are also Valeo or Bosch specific as well. Most of them use Bosch now, but there's a few odd balls (seems to be more of the AMG's) that came with Valeo, and they can't be interchanged.
