Hi,

My 940 Turbo 2.0L, has 270000Km.
During the last three years, I am experiencing extreme and fast wearing of the the alternator belt, all genuine Volvo belts.
The current belt has only 9000 Km and will break soon.

Please see some pictures I just took:

http://www.mediafire.com/view/v6smlpne7lea2a4/IMG_20201116_182429.jpg/file
http://www.mediafire.com/view/vr99u8amqkoab1f/IMG_20201116_182809.jpg/file
http://www.mediafire.com/view/bjuj6yj0zn3gfw7/IMG_20201116_182832.jpg/file
http://www.mediafire.com/view/a6r660m6rnbbibz/IMG_20201116_182858.jpg/file
http://www.mediafire.com/view/4laxk1bn95df0tv/IMG_20201116_182943.jpg/file

Typically they lasted about 60000 Km
The belt before my current one, it lasted 20000 Km
The one I currently have is on its way to break, after 9000 Km

When I saw the present belt deteriorate, I changed the alternator rubber bushing, but I am afraid the belt was already compromised.
I guess that in order to know if the rubber bushings were the problem, I need to put on a new belt.

In general, I did not have any issues, in 2016 I changed all the belts in one go, timing belt, AC, alternator, and power steering.
It may be a coincidence, but since then, the alternator ones do not last.

The pulleys seem perfectly aligned, but this is to the naked eye.

What is the best way to make sure the pulleys are perfectly aligned?

Any further advice is welcome.

Thank you,
Alex

Junk yards are strictly supply and demand

My junk yard has so many Volvo alternators that they are only $35 - In my experience they last over 200k.

a used alternator with around 100k is a better buy than many repairs.

Get a higher amperage unit if you have a choice.

I think you are on the right track with misalignment. If you have a metal ruler, level, or proper machinist straight-edge, put it on the front of the alt pulley and see if it "runs into" the belt or crank pulley.

I see some squish in the bushings already. If they were really cheap (uro parts?), or the tensioner was set way too tight (although you've replaced a lot of these, so seems unlikely), I could see that affecting it.

That fraying is noteworthy too. I would turn the engine slowly by hand and see if you can find a burr.

Another option is the alternator bearings being worn and allowing the pulley to rotate relative to the body. It's possible to have them rebuilt, but I'm not sure it's worthwhile. If the belt seems to bounce while the engine is running, that is a sign of failing bearings, although I'm not sure if it uses ball bearings or metal bushings internally. If you relieve the tension on the belt, and try the straight edge again, and now the straight-edge does *not* hit the belt or crank pulley... well, it could still be bushings.

How did the previous belt fare?

Dear Metallo,

Hope you're well. In photo _189243, the belt seems slightly skewed, i.e., rotated: the top outer edge of the belt - that closest to the radiator - seems slightly higher than the pulley's rim, while the inner edge (that closest to the engine) is slightly below the pulley's rim.

That misaligment may be due to the failure of the crankshaft pulley. That pulley - forgive me if I labor the obvious - consists of an outer steel ring on which ride the belts, which outer ring is bonded with rubber to an inner steel core, which core is bolted to the crankshaft.

If the rubber bond starts to fail, the outer ring's face may no longer be perfectly parallel with respect to the inner core. The pulley will therefore wobble as it spins. That wobble will cause the belt constantly to shift from side-to-side.

Using a strong light, watch the pulley, when the engine is running. Be careful to keep clothing, hair, etc., clear of the moving belt. See if there is indeed a slight wobble in the crankshaft pulley. If so, that's like the cause of accelerated belt wear.

Alternatively, look at the alternator pulley. If the alternator pulley's flats are not precisely parallel with the crankshaft pulley's flats, then the belt will be skewed. You can check pulley alignment with a straight-edge, e.g., any piece of metal known to be straight, e.g., a level or a yard/meter stick. A skewed alternator pulley may result from worn mounting bushings.

I periodically re-tension the alternator drive belt because the belt's length - relative to the other two drive belts - puts it at risk of over-flexing, which raises fatigue and so failure risk. I adjust so that with an index finger, I can depress the belt about 3/16" (about 4.5mm).

On a '94 940 I change drive belts at about 20,000 miles (35,000 Km) or about five years. Rubber deteriorates with exposure to heat and air. The replaced belts showed no signs of fraying or edge wear. The change was purely preventive.

Hope this helps.

Yours faithfully,

Spook

Hi Spook,

This morning I took a video of the 'belts' with engine running.
I can see the power steering belt wobbling, and hear the squealing sound too which appears to come from the power steering pulley.
If I spray some water on the power steering pulley, the squealing temporary stops, however the same happens if I spray the crankshaft pulley.

Here's the link to watch the video:

https://www.mediafire.com/file/xelupbwts58qco8/VID_20201222_095706.mp4/file

The question is, which pulley is the root cause of the problem?

The power steering pulley.... it does not look like it is made of two different cores like the crankshaft one, so it could well be the crankshaft pulley causing the wobbling of the power steering belt.

However, I see no wobbling of the alternator belt, but I guess it does not necessarily have to wobble, as you said, the outer ring's face may no longer be perfectly parallel with respect to the inner core.

I would exclude the alternator pulley, also because I changed the bushing a few months ago.

Thank you for your help :)

Alex

Dear Metallo,

Hope you're well. The power steering pulley is made entirely of steel.

To see if the crank pulley has failed, use white paint to draw a thin line from the crank bolt to the pulley's outer face. The line will cross the edge of the rubber, that bonds the core (where is the crank bolt) to the outer ring, on which ride the drive belts.

Drive the car. If the straight white line now consists of two separate white line segments, then the crank pulley has failed: the rubber no longer bonds the core and the outer ring. The crank pulley must be replaced.

If the crank pulley is OK, it is possible that the mount for the power steering pump has failed, or that the power steering pump's bearings have failed. The mount no longer is available. A replacement power steering pump can be had.

Hope this helps.

Happy and Safe Holidays!

Yours faithfully,

Spook

Hi Spook,

Thank you for your advice.
By 'mount' you mean the bracket holding the pump?

In your opinion, should the power steering be the problem, would that be the reason for the alternator belt to wear so fast??
In theory, it should not affect the alternator belt, but let's see, I will try to
draw the white line and see what happens with the crank pulley.

All the best to you too during the festivities and for 2021!

Alex

Dear Metallo,

Hope you're well. Yes. If the power steering pump bracket has worn, such that the pump is skewed, then the crank pulley may have been stressed and so failed.

If the crank pulley is the factory-installed item, it doesn't owe you much.

Happy Holidays and a Good & Healthy 2021!

Yours faithfully,

Spook

Hi Spook,

I did follow your advice and painted a line on the crank pulley, turned the engine on idle for 5 minutes, but I did not see any misalignment in the line.

Would I need to drive the car for longer to see if there is an issue between the inner and outer core, or do you think that 5 minutes are sufficient?

Looking at the power steering pulley, I didn't know that its bracket can wear.

If I want to disassemble the power steering pulley and its bracket, can I do it from the top, or do I have to lay under the car?
It is just an issue for me to do this work in the winter, even if my garage can be heated, laying on the ground on a creeper, the cold is coming from the slab and it is not ideal to work. It is still a Canadian winter! :)

Alex

Dear Metallo,

Hope you're well and that the Holidays have been enjoyable. To test a crank pulley, it is better to drive the car. The pulley's sections may require the energy applied by acceleration, before they'll move relative to each other.

The power steering bracket is - if I recall correctly - made of aluminum. It can wear, if a bolt works loose, and is not promptly re-snugged. If the bracket wiggles - ever so slightly - relative to the engine block, the bracket's hole will deform. This makes it next-to-impossible to align the pump.

The power steering pump pulley is pressed onto the pump's shaft, so I think it cannot be removed and replaced, while the pump is affixed to its bracket.

I've never had to remove a power steering pump. I've changed the drive belt many times. That can be done from above. I'm pretty sure that removing the pump requires working from below.

Before removing the power steering pump: (a) try to tighten the power steering pump's mounting bolts and (b) use a straight edge to see if the pulley's face is exactly parallel with the crank pulley's face. If the power steering pump pulley's face is parallel with the front of the engine block, then there's no reason to suspect the power steering pulley.

Cheap-and-effective insulation - when one has to lay on a cold surface - are several sheets of corrugated cardboard, one atop the other. I've given up using creepers: they tend to shift, making it hard to exert leverage.

Hope this helps.

All the Best for 2021!

Yours faithfully,

Spook

Hi Spook,

I finally got some time to remove the alternator belt.

The first thing I have done is to verify the alignment, I found the alternator misaligned by 2-3 mm, so the alternator should be closer to the front of the car.
I also put a level on the flats and that could be the other problem, it is skewed.

Now, I am not sure if this is meant to be like that, but I doubt.

I also measured the alignment between the crank pulley and the A/C, it looks OK.

Now, consider that the alternator bushings are new, genuine Volvo parts.

At this point it is hard to say how to reposition the alternator given that there are no regulators for that kind of movement.
The only thing would be to undo the bracket from the block, there is a bit of backslash I could use with the bolts, but I seriously doubt the bracket has moved during the years, that area has never been touched in 24 years.

https://www.mediafire.com/convkey/d82a/uif2qj46fm0xuza6g.jpg
https://www.mediafire.com/convkey/2831/1nj5wv4gwqfkkot6g.jpg
https://www.mediafire.com/convkey/1721/4jhgimqpbq0s3a86g.jpg
https://www.mediafire.com/convkey/f637/4pyo4c8hlue172h6g.jpg
https://www.mediafire.com/convkey/439a/a51mkabqugffpy96g.jpg

Do you see anything I do not see from the images?

Thank you,
Alex

Dear Metallo,

Hope you're well. Yes. The black rubber bushing in the upper front position has failed. The alternator's face no longer is perfectly perpendicular vis-a-vis the side of the engine.

The bushing seems to have been made of a too-soft rubber and/or with a bolt hole that is slightly too large. One or both of these defects allows the alternator to move, when the belt is tensioned. That misalignment accounts for premature drive belt wear.

With rubber items, it is next-to-impossible to know how the rubber was compounded and processed. The rubber's "ingredients" and processing determine how elastic and durable the part will be. These parameters cannot be ascertained by "eye-balling". An aftermarket rubber item may be identical as to dimensions, but be very different as to performance.

I presume - without having documentary proof - that the rubber used in Volvo-supplied bushings is compounded and processed so as to have consistent elasticity. Thus, whenever made, they perform the same way. That may not be so for aftermarket bushing suppliers.

I agree that it is very unlikely that the alternator's mounting bracket - that secures it to the engine block - has failed. For routine maintenance, I don't think there's a need to remove that bracket. Even so, check the bolts for tightness.

Hope this helps.

Stay well!!

Yours faithfully,

Spook

Hi Spook,

Just to be sure that there are no misunderstandings:

the black bushings are brand new from Volvo and if I look at them, they seem identical to the old ones in terms of bolt hole.

Maybe, if I add a spacer washer on the left bushing, that would push the alternator 2 mm to the front.

Stay well,
Alex

Dear Metallo,

Hope you're well. Volvo bushings can be distorted - damaged - by an over-tensioned or mis-aligned belt. When the bushing is put on a flat surface, wide-end-down, and the bolt inserted into the hole, is the bolt perfectly perpendicular to the flat surface? If so, then the bushing is in good order. If not, the bushing has been distorted.

That said, if when the belt is removed from the alternator's pulley, can the alternator be moved front-to-back on the mounting bracket. If so, then using washers to push the alternator forward (towards the radiator) may re-align it.

If not, then the mounting bracket - or the bolt-hole in the alternator's case - has somehow been damaged, such that the alternator cannot be mounted properly. I cannot recall a post reporting such problems.

I took a brand new Nippon Denso alternator and put through its top mounting holes, the long machine screw, that goes through the bushings. There is some "play", i.e., the holes in the alternator's case are larger than is the bolt's diameter. But the "play" is not enough to account for the misalignment that plagues you.

Hope this helps.

Yours faithfully,

Spook

Just to add my 2 cents to this discussion. Spook is of course correct in suggesting that a Genuine Volvo accessory bushing should keep the pulleys in original alignment longer than an aftermarket bushing. Given that the bushing isn't worn (as in compressed out of shape and easy to get in/out of the mounting hole), the next most important thing is belt tension. The more tension you put on the belt, the more the pulleys will be out of alignment, plain and simple, so do keep that in mind.

If you want to be a purest about this, if you've got all new accessory mounting bushings, have used a proper belt tensioning gauge to set the tension to manufacturer spec and if the pulleys are still out of alignment by more than an acceptable amount (a number off the top of my head being 3-5 mm) then shimming the mounting bracket on the block is a viable option. I've done that shimming once on a 240 and it was questionable whether I really had to, but with the accessory bushings I had on hand that seemed the simplest option and I would do it again if needed.

I still find your premature belt failures a bit difficult to comprehend, especialy if these were respectable brands. Belts may become horridly noisy when out of alignment or undertensioned, but shouldn't prematurely fail as you suggest unless they're totally tired from age, of the incorrect width (a definite possibility for you if you aren't well versed in belt cross reference sizing), of extremely inferior construction, horridly overtensioned or riding in seriously damaged pulleys.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Spook, All,

Thank you very much for your advice.

I will definitely check if there is a misalignment and will verify any other points you have mentioned.
One thing I can state for sure: since I track any kind of maintenance work I do on my car, each one of the first four belts lasted between 50-60000 Km, with no issues.

So yes, something is wrong for sure and I need to find the root cause.

I will keep you updated.

Thank you,
Alex

Are you sure Volvo is using the same belt supplier? Brand Labels varies with suppliers.

Yes the alt belt is the one that will wear out first. Typical mileage is about 10,000 to 20,000 km. This is supposed to coincide with normal oil change interval of 16,000km. So when you change your oil, you also replace the belts.

The power steering and AC belts usually wears out almost forever in my experience until some noise develops. For the alt belt, pulley to pulley distance is the longest of all three belts, so there will be some visible belt vibrations at idle. I think these vibrations is killing the alt belt faster, as other belts don't vibrate at all and they last longer.

The manual mentioned about adjusting the tension so that the belt deflects about 5mm to 10mm at its longest run. This generally applies to all belts. However for the alt belt I found out that the best adjustment is done while engine is running and fully warmed up. Aim for the least amount of vibration but not until none at all, as this already means overtension and might shorten your alt bearings' life.

No, I don't think our simple V-belts could last till 60,000km. This 60,000-100,000km interval usually applies to modern multi-ribbed belts ie. serpentine belts.

Amarin.

Look for a burr on each pulley.
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