just looking for general comments and suggestions about replacing the belt tensioner and belt for a 93 190E 2.6 with the M103 motor.

replacing it because its been rainy lately in sunny socal and it left my car with a squeaking noise around the belt. I inspected the belt and saw that it was cracked all over along the ribs and when I checked the tensioner, the pointer was way past the triangle/max point. because of this, I have a feeling that if I just replace the belt, I wont be able to tension the belt properly.

how is the space available to work with in that area for replacing the parts? do I need to remove the radiator on a 190E? and what is the sealant that I am reading in the FSM? i heard something about an O-ring? is there a part number available I can look up?

There is very little room in which to work changing the tensioner on these cars.

If you haven't done the job before It's actually easier to remove the radiator. This in itself is easy.
You need to remove the fan, fan clutch, pulleys for the water pump,power steering and fan. - Its easier if you loosen the bolts on these pulleys with the belt still on and tensioned.
Once all these parts are out you will see a Y bracket that keeps the tensioner in. Removing the tensioner is pretty straight forward from this point.

There is a 19mm bolt that tightens the tensioner - you will find it. Loosen it before making any movement with the tensioner lever.

Do a search on M103 tensioner - there are many posts on this.

what is the o-ring or sealant used on the Y bracket keeping the tensioner in? is it the same sealant used to seal the timing cover gasket?

i used engine sealant & worked fine.A new tensioner and belt will do the necessary repair .The tensioner is a weak point on the 103 engine .it tilts sideways when worn out causing wear on the inner side of the belt as well as the chirping sound.
search for belt tensioner 103 .
mak
300se

The o-ring is referred to simply as the "timing cover o-ring". The sealant is the same as used for the timing cover. Taking the radiator out isn't absolutely necessary but it will get the hoses out of your way and give much more room to work.

When you take the fan and fan pulley off, you'll find that the fan arbor and bearing are set in an aluminum casting that mounts (4 bolts) to the front of the timing cover, The Bottom right bolt (as you face it) is where the the longest arm of the "Y" bracket for the belt tensioner is fastened. If you take this aluminum casting off (referred to as the fan bearing bracket) you'll see that that bottom right bolt hole in the lower timing cover that it mounts to is slightly larger than the others. This is where the o-ring goes. I have found that the o-ring they give you is too large to seal well around the bolt and too thin to protrude out of the bolt hole opening to provide any kind of seal against the aluminum fan bearing bracket. It's really kind of pointless set up. It is then suggested that sealant be applied around that bolt hole on the mating surfaces of the aluminum bracket and the timing cover. It is further suggested that sealant also be applied on both sides of the "Y" bracket at that bolt hole.
Assuming that there is no oil leak at that hole now, it is likely that the o-ring and sealant is already in place under the bracket and therefore is no need to take the fan bearing bracket off and disturb or replace the o-ring, but it would still be prudent (and/or sufficient) to apply the sealant on either side of the "Y" bracket when you put it back together.
The proper sealant is the mercedes black timing cover silicone. Don't have a part number on hand but any MB parts counter will know what you need. There's a Permatex product that is suitable as well but I don't recall the stock # of that either.

If yo look on the top right side of the fan bearing bracket you'll see two short parallel ridges pointing toward the fan arbor. Bend the last inch or so of a foot long 3/16" rod so it is shy of an "L" shape (about 55-60°). Lay the "foot" of the bent rod in between the two ridges and slide it forward as you turn the fan arbor. It should find a corresponding hole in the arbor to engage in and lock the arbor in place so you can easily unbolt the fan.

As far as the rest of the tensioner procedure, I can't do any better than the excellent article already written up in the DIY section of the forum.

very relevant information from' long gone'. with this much detail provided i am sure you will be able to do a perfect job of reinstalling the tensioner and belt.
good luck
mak

I will give you some good reasons for removing the radiator and hoses.

Those items on your car may have been installed since the car was new. The radiator plastic neck is a weak point. By not disconnectiong the hoses you could be putting pressure on the weak point by moving the hoses around when doing works in the general area.

If your hoses are old you are probably better off changing them anyway - while you have the coolant out of the system.

If you have experience changing out the water pump or tensioner than you may get away with not removing the radiator. It's a much easier job in a M103 engined W124 where there is much more room. The M103 was shoe horned into the W201 and work room is at a premium.

I'd have to agree with Ivanerrol on that!