Changing Belts 240d - PeachParts Mercedes-Benz Forum

rob240d · #1 02-08-2009, 01:25 PM

Hi,

My fan belt snapped the other day and I topped the car up with water and limped home hopefully it's ok.

I have a haynes manual on the car that does not explain how to change the belts. Maybe it's supposed to be sraight forward

I searched the forums and understand I need to take the other two belts off to get to the alternator belt. How do i do this.

Do I need to undo the big nut on the top of the AC pump??
Can someone give me some advice please???

Thanks

jt20 · #2 02-08-2009, 01:53 PM

why did you need to add water?

Each accessory (alternator, A/C pump / Power Steering) has an adjustable assembly on which it pivots. There are a few bolts involved with each one that must bee loosened so that the assembly can be tilted - reducing tension in the belt.

once the primary bolts are loosened, there are usually adjusting nuts which provide a mechanical means of tensing the respective belt.

Each accessory that comes before the belt you need to access must be removed.

Cr from Texas · #3 02-08-2009, 02:09 PM

I usually assume the belts are all the same age and replace all three as soon as one fails. Same labor as replacing the last one only.

rob240d · #4 02-08-2009, 02:24 PM

Ok.Good thinking. Thanks, I will replace all the belts.
I topped up with water because the water pump was not functioning and it got very hot trying to get home.

Where is the pivot. I would assume in the middle but there is only the pulley at the bottom and what ever is at the top? Is it the top of the belt the area I need to be looking?

pizzachef · #5 02-08-2009, 02:52 PM

No, each component has its own pivot. The AC compressor, the alternator, and the PS pump. They each have 3 bolts that you loosen (don't remove them) then an adjusting/tensioning bolt that rotates the component about one of the 3 mounting bolts. So one of the 3 mounting bolts is the pivot point. It takes different combinations of sockets, extensions, and open/box wrenches to get to them all. Nothing fancy, just a full set of sockets and wrenches.

The factory manual shows how to find the bolts to loosen. If you're having trouble finding the bolts to loosed, I'll see if I can send you that page.

Putting the front tires on ramps helps a lot. Use a flashlight and look on the front and back sides of the three components.

johnbonds · #6 02-08-2009, 02:55 PM

I just did this a coupla months ago. Really got hung up on the a/c compressor which just didn't want to move. Finally one of the forum gurus suggested I should loosen the clamp on the a/c hoses coming from the compressor to get the movement. It worked and the job was reasonable after that.

John Bonds
'82 240D 4sp
South Carolina

rob240d · #7 02-08-2009, 03:04 PM

Thanks pizzachef. I do not have the factory manual so that knowledge will be useful.
I read your previous post John thanks, another useful tip and I thought it was going to be a half hour job!

Yak · #8 05-01-2011, 12:52 PM

Lots of info here, some accurate, some not. It'll be difficult to find a DIY that covers all the belts, so try searching for DIYs on each component: P/S pump, A/C compressor and alternator. You'll probably find good pics for each one that will help.

The parts may have 4 bolts that need loosened in order to get the parts to move. For example, look at the pic in post 2 in this thread: Installing a CompressorWorks R4 into a W123

The P/S pump "pivots" on the upper inboard bolt, slides on the lower inboard and outboard bolts (so these 3 bolts lock it in place) and there's a tensioning bolt upper outboard (that helps you adjust the tension ONLY when the other 3 are loose).

The R-4 A/C compressor is similar in layout. Don't know about the York.

The alternator is a little different and there are various threads on the tensioner. It has a bracket that needs to pivot (upper inboard), a bolt on the alternator that needs to pivot (lower, through the alternator) and a tensioner that needs to slide that may/may not have a 90 degree bolt that is probably stripped or bent from misuse.

mjquillici · #9 02-08-2009, 09:47 PM

Putting your car on ramps helps a great deal. Also, locating all four of the bolts (including the adjusting bolt) on each accessory can be difficult, but once you get the accessory to move, it's not that bad. I also had a hard time with the a/c compressor, because there was so much oil/grease built up on the bracket. It just didn't want to move.

t walgamuth · #10 02-09-2009, 05:53 AM

I hope you didn't hurt anything driving it home wo your water pump!

Thats really not a good idea.

rob240d · #11 02-09-2009, 08:15 AM

Yes. Driving without any cooling was not an ideal situation to be in. I only had to drive about 4 miles. I to hope it's ok.

Does anyone have a picture of the components and or the pivot and tension areas? ?

Thanks

vstech · #12 02-09-2009, 09:14 AM

ok, start with the power steering pump and get a 13mm socket, and a 3" extension, also have a 13mm box end (a wratchet wrench is awesome here...) look on the face of the pump, you will see three 13mm bolts facing front. hold them with the box end, and get the socket on the back side of each bolt and loosen. now on the machined edge just below the cap for the pump you will see a single nut facing up. that is the tensioner bolt. loosen that and you will have slack to remove the belt.
next is the A/C compressor. you will need a 17 or 19mm, not sure exactly I used a box ratchet wrench but a socket and ratchet should be good. there are again three bolts holding it still, they face the back of the motor. on the back side of the compressor. as mentioned you should also loosen the metal clamp holding the freon lines to the frame of the car. that bolt is 13mm I think. anyway, once all 4 of those are loose, on the front of the compressor is a strap with a nut on the end, and you loosen the nut to gain slack to get the compressor belt off.
finally the alt/wp belt/s.
it gets a bit tricky here depending on the model if you have egr and a heat shield above your alt, you will in all likelyhood need to remove the shield.
either way, you will need that 17mm box wrench again, and loosen from the back of the alt the three 17mm bolts you find back there. then on the bracket holding the alt to the block of the car, you will see a funky long nut on a threaded rod sticking out of the top bolt on the alt. that you should immediatly soak in PB Blaster rust penetrant. aero kroil is better. let it soak for an hour or so, you don't wanna just wrench on that bolt... to replace it is like $50~ once you are sure it's free, loosen it, and go mount your new belts. by the way. random parts stores don't stock the correct belts... they stock "close" belts... they will slip. go to the dealer or an import parts store and get the correct metric belts!
reverse procedure and set deflection and you're good!

rob240d · #13 02-09-2009, 10:10 AM

Top Man! Thank you. They are the sort of instructions I like/need.
I bought, like you say, a near fitting belt from Autodiscount but have since ordered 3 new belts that are model specific.

I will give the bolt heads and nuts a good soaking before starting the job.

t walgamuth · #14 02-09-2009, 08:32 PM

four miles? good chance you're ok.

rob240d · #15 02-13-2009, 01:13 PM

I have just managed to take another look at the job and am completely confused still. I am wondering if my European car is different to US models.

I have a picture with some colours to help use as a reference but I am unable to see any slackening bolts (3)? Just big Bolts at the top of the Air conditioning pump and a wheel with 6 bolts on for the Power steering?

Can anyone shed any light please!?

http://www.peachparts.com/shopforum/album.php?albumid=181&pictureid=992