1.6 diesel single belt length? Belt keeps snapping (Syncro Doka)

[damagd]

1.6 td previous owner upgraded alternator from 65a to 90a. I've owned it for two years now and probably gone through about 5 belts. It's a single belt system, but I know this engine was set up to use two belts originally. Can't remember the size of the original belt, but when it first snapped and I tried to use the same size, it seemed like it was too long. So I've been trying multiple sizes out since then after each snap. I always feel like I'm tensioning it correctly, but it eventually starts to slip until it snaps. Do I need to go back to the two belt system? (If so, I'll have to find a pulley and shims for the water pump) Or do I need to fab up a new tensioning bracket that is longer and curved so that I can swing the alternator up higher? (I can not swing it much now until it maxes out the slot on the bracket. About 2 inches or so.) Or do I need to just use the correct belt size? (Which is impossible for me to find through many many internet searches.)

[MarkWard]

I would be looking at a rabbit diesel without ac if you are looking for a single belt solution. You'd likely need the rabbit alternator brackets, but they did run successfully a single belt.

Can't account for why you are eating belts assuming alignment and pitch is correct.

It used to be autopart places had a rack of belts in ascending order of size.

Example and belt that is 10 x 950 the next size up would be 10 x 955 the next smaller belt would be 10 x 945

So, take your last belt size and work from there. A belt that you need to walk on, will likely have enough adjustment for future wear.
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[damagd]

It's a replacement engine. Not sure what it is out of, but engine code is CY. No AC, No power steering. I can add pics later if you think that would help.

[4Gears4Tires]

[MarkWard]

I assume you carry a new spare belt? Post the specs or a picture of the cardboard surround.
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[damagd]

[MarkWard]

Can You read the numbers on the back side of the belt? Short of that, move the alternator to the bottom of the slot. Take a piece of clothes line and wrap all 3 pulleys. End to end of the rope is your measurement. Lay it out and measure with a tape. Then convert to mm. Your measurement x 25.4. = metric length. Use that to find a belt. We use continental belts, but gates and dayco are fine. Actual pitch is 9.5 , but 10 is fine.
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[damagd]

[akyrie]

If you snap or lose another belt, check your injection pump mounting bolts. I had a brace between my engine and the top of my injection pump to help hold it still(on an AAZ that was losing belts.)
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[damagd]

[MarkWard]

You describe running out of adjustment with the belts you been using. A slightly shorter belt will help that. You set the belt around the water pump pulley and the alternator pulley. Slide the belt into the groove on the crank pulley as far as you can. Take a piece of 80 grit sandpaper and insert it between the crank pulley and where the belt crosses the pulley lip edge. Grab your 19 mm socket on a long ratchet and turn the crank pulley. This should walk it over the pulley lip and not damage the belt. Once it’s on, you can snug it up. I too recall an L bracket between the alternator and pump bracket.

I have a complete 1.6 for sale here. I imagine one of the pictures you might be able to see the alt attachment point.

edit: Yes you can make out the bracket in the one picture. https://www.thesamba.com/vw/classifieds/detail.php?id=2289690
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[DanHoug]

i ran a single belt on an 89 Jetta 1.6 diesel for 140k miles. you should check:

- the belt runs in the top of the pulleys, maybe even *slightly* proud of the top of the pulley. if it touches the bottom of the pulley it will slip and burn in short order. this is determined by the belt width and requires experimentation.

- belt length. again experimentation. all the internet reseach means nothings at this point with a different alternator on there. you want to just barely be able to get the belt on with the alt swung as close to the crank as possible.

- belt quality. there's some really terrible belts out there. the $5 ones are only good for experimentation to find the length. then buy a NAPA Premium/Gates belt. expect to pay $20-$25 for a decent belt.

- pulley alignment as others have mentioned. this is critical and people swap alternators with different nose lengths on the pulley.

- run a soft cloth around the pulley groove. you are testing the surface to see if there is a sharp burr that snags the cloth.

- spin the alternator pulley without the belt on. is it free and happy and continues to spin for a while? if not, you need new bearings.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
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