I can't tell if it's perpendicular or not think I'll just try to replace it along with a new belt. Does it make sense to also replace the idler pulley in the process?!

Sounds like at least the fan needs to be removed for this job - does the radiator need to come out as well?!

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

I did replace the idler pulley, but the old pulley looked fine.

Apparently, you can do it without removing the fan, but you'd need to be Houdini. The radiator does not need removal.

Thanks - any interest in building a DIY article if I take some photos along the way and to the writeup?!

James

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

We always have interest in well written and photographed repair documents.

don't bother with the fan. just work the belt over the blades one at a time. a couple hand tools and ur golden. i did mine in a parking lot at night in about 15 minutes.

the hardest thing is remembering the routing over the pulleys

__________________
1987 300TDT
1981 VW MKI Caddy 1.6 diesel, waiting on engine swap
1983 D-50 Power Ram 4x4 "Mitsubishi" 2.3 turbo diesel
assorted gas powered crap and motorcycles

RIP: 1984 300TDT, 1982 300TDT, 1984 190D 2.2, 1992 300D 2.5, 1987 300TDT, 1982 Maxima LD28, 1983 Maxima LD28, Isuzu C223 P'ups X3, 1983 Holiday Rambler 6.2 Banks turbo diesel, 1984 Winnebago LeSharo 2.1 TD, 1985 Allegro 6.5

Wow, you're good!...

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

My '91 350sdl shock strut that dampens the tensioner vibration had weakened and caused a real bad vibration throughout the range of pedal, but especially at idle. You can take the strut off easily and check for wobble in the in the tensioner before you order one. The springs have a tendency to weaken or break.
Coat hanger bent with 1 inch 90 degree at end will pull the belt between the tensioner and h20 pump easily to wrap it around tensioner. I was afraid to put too much tension on the plastic piece so I vice gripped the spring and manned it over the keeper, and yes, I strained my guts out.

__________________

I LOVE CATS....AND FRIES

1981 300sd
1983 300sd
1985 300d
1983 300cd
1991 350sdl

James,

You do not need to remove the fan to thread in the new belt.

1) Put a suitably long and 15 mm thick lever into the top of the tensioner (the "hook" that holds the spring), remove the nut, bolt and drop the tensioner gently by lowering the lever (towards the driver side). Remove the tensioning spring and place it aside.

2) With the belt slack, pull it from the bottom first around the blades of the cooling fan. Pull the the belt from the center pulley and drop the loop slack. Pull the top of the belt around the cooling fan. There is room between fan blade and fan shroud.

3) Insert belt around bottom and top of the fan blade, the belt will just hang loose near the pulleys, don't try to rest it on anything you are going to be looping the belt to get it around the center pulley first

4) Fold the belt at the top part in half (ridged side out, slick side goes around center pulley) and thread it diagonally from the direction of the steering pump and imagining your target as the pulley on the alternator at the opposite side at the bottom passenger side of the engine

5) pull the belt from the bottom around the center pulley and from the top, back over the water pump/fan belt pulley

6) pull the loop around the alternator, then the A/C compressor pulley, then the steering pump pulley

7) make sure there are no twists in the pulley from all the gymnastics, pull the belt back and forth to make sure it is centered on the pulley ridges even though still quite loose

8) re-attach the spring tensioner on it's bottom hook and top hook and insert the 15 mm tool that is in the car kit tool roll, or any half-foot to foot long metal tube to lever the spring back to the position that allows you to re-insert the bolt from the rear - this is a near three handed operation, but a helper can tap the bolt back into the top tenioner hook, or just hang over the engine bay with full body weight on the lever while you tap the bolt in yourself with a small mallet - tighten nut snuggly - check belt tension

9) Start engine, check belt.

If you do this a couple of times you'll realize the whole procedure is less than 10 minutes and only the nut and bolt of the tensioner needs removing.

-bh

2x The belt change on the 60x is an easy job. You don't even need to go under the car and despite the tight clearances there's more then enough room to work.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I've tried to do it only from up top but between grease and scratches on my forearms, I tend to avoid it. I prefer to jump under the car to get a better look and avoid getting a twist in the belt when I thread it around the fan. Perhaps I'd try it again if I had a box of those arm-pit length gloves veterinarians utilize for (ahem) inseminating cows.

-bh

Thanks BH - though I may need to remove the fan afterall, since in addition to the belt I plan on R/R the tensioner as well as the idler pulley in the same exercise as well -as I've got this wicked squeal under load that I'm hoping the r/r can cure.

Thx for the detailed steps though - they will come in handy on the final re-install of the belt.

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Removed and replace the belt, the idler pulley (bad bearing), the tensioner - all brand new. Cleaned everything with wire brush and sprayed it good with Brake Cleaner. I'm pretty sure the belt is routed correctly to the FSM diagram from Brian.

So most of these components are new now. I went for a drive, started off gently and worked my way up - wouldn't you know it... the squeal is still there!

When I accelerate from a stop, it doesn't squeal - it starts squealing under load around 2500 - 3000 rpms. The squeal isn't constant, it varies with the accelerator. When I back off my foot it subsides, when I press on it it increases.

I guess it's still the belt slipping but why?! Could it be the tensioner spring that weakened and isn't providing proper tension on the belt?! The spring and the dampener are the only things I didn't replace in that mechanism.

Also, another thought: could this sound be produced by a bad Turbo bearing?!...

THx,
James

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

The belt doesn't know about any engine load. It is loaded based upon the accessory load..........alternator, a/c compressor, p/s pump, water pump.

You can load the belt by turning the wheel while the vehicle is running in the driveway at idle and/or put the headlights and a/c on. This will generate a belt squeal if it's load related.

However, I'm doubting the belt as the culprit for the squeal because it's related to engine load, not belt load.

Any other guesses what the engine-load squeal might be?! How about my Turbo bearing theory!?

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

MercFan,

Noises are notoriously difficult to diagnose without being there. Even the terms for describing noises tend to fall well short of ideal (linguistic shortfall in most languages so it seems).

Any accessory with a pulley bearing can produce atrocious noises. My main culprits would be AC, alternator and water pump, but this is all guess work. Steering pumps mostly don't seem to get noisy unless you have a bad leak and the fluid level is low.

Do you hear the noise only when the AC is engaged? With no electrical loads, is the noise less noticeable? These are the sorts of things you need to check.

Pinpointing the location of the noise in narrow between a spinning fan and the drive bolts is maddening, but I'm confident you'll find it, particularly with a helper in the car while you lean over, or get under (most of the interesting accessories are on the bottom run of the belt) and turn your head a bit to isolate the noise while the helper turns on accessories, pulls the steering, wheel, etc.

-bh