Belt squeals
 

Started doing it today… Issue #1: My alternator belt squeals as the engine revolution goes up. It ONLY happens if the heat is switched on in the 2nd position or up (3rd or 4th). :) Symptom #2: When I switch the heat on, the voltage gauge shows the voltage dropping quickly down, immediately, from 14-15V to 10V. It gets even lower if the headlights are on, even more if the high beam is on (with the heat). Rising rpm does not stop the squeal nor rises the voltage levels back to normal. If heat is not on, there is no squeal.
In the past I rarely saw my voltage dropping down lower than 12V, and never more than 1-2 Volts at once... and those times it always happened gradually/slowly (for example when I switched the seat heaters on with full blast of heat, radio, headlights+front fog lights+rear fog lights on +radio +etc ). That`s normal, I think, that in that case the voltage drops from 15 to 12-13-14, whatever, and stays there, being lower than the average I see when driving with nothing on (daytime).
Now, as I put the heat on, the voltage immediately jumps down from 15V to 10-11Volts and the belt starts to squeal too as the rpm increases. It does not stop. If the heat is not on, the voltage stays around 14-15V and there is no belt noise at all. (PS.: The digital Voltmeter shows 14.06V in battery after many days of no-use.)
It’s a nasty cold rain here and completely dark now but I`d like to figure this out tomorrow. Any ideas so far?

Alternator belt needs to be very tight on these. If yours slips when electrical load is applied, see if you can solve the problem by tightening the belt. Helps to use a crowbar for leverage but be careful not to place the crowbar against any fragile parts.

Also, check the condition of the belt itself.

If the belt is slipping, the gauge will read lower because the alternator is not able to meet the electrical demand.

If tightening the belt does not help (should at least stop the squealing), then start looking at possible failing heater fan or resistor pack, and wiring issues.

Belt was not tight at all.
 

Thanks Ngoma for your opinion! Right after I posted my question here around midnight, I could not got to sleep (again) so I adjusted the belt in the middle of the night. (I was about to post another question again with the results of the fix.) I then saw that you answered me... Just as you suggested, the belt was not tight at all. It has a Volvo belt on the alternator and it looks, feels healthy. Squealing stopped right after tightening the belt. I did what you suggested but I was not sure how tight it is allowed to be. I attacked the 13mm nut and adjusted it... now it`s tighter but I can still push the belt `down` half an inch. Shall I go ahead and do it again?
I still have the voltage gauge drop big time if stuff inside the car is turned on, especially when I turn the heat on full blast (with lights etc)....
The high-pitched squealing belt noise stopped though. I might want to go back and tighten the belt more. How would you make sure that tension is right?
I`m curious if it is a good idea to use an additional bolt/nut in that gap to avoid any future incidents like this one?

If the belt stopped slipping (squealing) then you got it tight enough. How much did that improve the low voltage situation?

PS: Try a different DVOM. A fully charged 12V auto battery should read 12.6-12.8 VDC. Your measurement of 14.06 for a resting battery is way too high.

Your FLAPS should offer free testing of the charging system and battery, have you tried that?

Alternator belt tension
 

I tightened the belt. I could make it even tighter if I knew how much the desired/suggested max tension is. At this stage I can still bend the belt slightly or push it down half an inch. It could be tighter but I was not sure about specifications. The slipping ended so there`s no belt noise any more but voltage still drops down immediately to 10-11 Volts right after I switch things on such as heating, fogs, headlights, etc, especially if I combine these... I will check on the battery but I guess it is not malfunctioning yet. I do remember though that my voltage gauge showed around 15-16V all times throughout thousands of miles. Also, my newish loose alternator belt issue might be somehow related to my power steering pump minor leaking and/or that belt`s abnormal running angle (misaligned a bit). I have a post about that too. I can`t think too much about this car or anything right now these days but will be on it very soon, hopefully.

Did the tachometer reading also drop when the squealing occurs? Usually when the alternator belt is slipping you can see it on the tach, since the tach reads RPM off the alternator.

Now that the squealing is gone, but you are still noticing the voltmeter reading low when the electrical load is high, does the tach still stay steady? If you are seeing big variations in your voltmeter reading but the tach is reading normally, then the belt is probably tight enough now and the voltmeter is probably just a little oversensitive given the range of its fluctuation. Well, either that or the voltage regulator is acting up and/or brushes are worn.... You might want to get access to a known accurate voltmeter and check charging voltage at the battery with engine idling and electrical accessories, lights etc turned on to ensure that the alternator output is sufficient and correct, but it sounds like you have probably cured it.

belt issue
 

My two 84 wagon's belts (both of them!) squealed right after startup due to glow plug and starter drain. Would eventually go away. Eventually, you should be getting more voltage even under loads presented by heater, lights, whatever. I believe you have a regulator/alt problem to further diagnose.

Long gone alternator belt squeaky noise came back as a Xmas present
 

Well, I grabbed the 13mm+a longer bar &Carefully tightened the belt. Probably not enough because noise stays so I`ll redo it tomorrow.

Usually after cold starts, I started hearing this sh!t squeal again. (for up to a minute). Higher loads (Using heater+fogs+radio,etc) can still trigger same sounds while car`s in motion at lower rpm (any speed, obviously) -->

The belt is definitely not tight. A closer look is telling me it is not in best shape either... WTHeck. (After `cracking up` at multiple spots, did it go elongated enough to become loose??)
I`ll be trying to find a Seller (Volvoparts,tasca,Ipd dont have it)... an 85 D Volvo is almost always non-existent in most of the search boxes.

How important is it to use OE? Sayings about Volvo quality are not always true but This same exact belt have already had its side/edge damages present years ago but never gave up really so i left it alone...by now it does look more disintegrated.

Written on belt: `VOLVO 966 894 9,5 x 750 La Made in Germany 6135`
I`m sure Volvo used same belt on many of their other models also.
Thanks for suggestions. I attached a few fresh pictures to illustrate this cr@p.

Belts get narrower, dryer and slicker with age. If they werar down to hit the bottom of the V, they always slip. Slip also glazes the pulley, promoting more slip. All of these things add likely hood of squeal. Volvo's wierd acessory bushings don't help much either. That belt is old enough even a crap one will be better.
Sometimes wire bushing belts with the engine running will give them a few more weeks, but sometimes you lose your brush. Easier on cars without a mechanical fan usually.

The blower motor is also probably against you, it's a huge current draw, and since they are mounted in such a way as to water the bearing, in 740's they are never in good shape(at least they are easy to change).

Funny story, I took a ride in my friends all electric Chevy Spark which can monitor such things, and in town with heats and light, our power consumption was ~45% propulsion, 55% driver comfort.

That belt looks pretty tired. Not at all important to use OE here; any good-quality V-belt will do. Conti, Gates, Dayco, etc. The alt belt on these is short and wears more quickly than the others.

Getting it tight and keeping it that way takes some tricks... I like to loosen the large (13mm head) bolt that goes thru the end of the lower adjuster strap into the oil pump, loosen the adjuster nut, tension the belt, tighten the adjuster nut while leaving the bolt at the other end loose, let off my prybar to let the belt pull the slack out of the joint where the bolt is, tighten the bolt, then loosen the adjuster nut and tighten belt again. Keeps the adjustment from shifting; without doing this I usually find it needs re-tensioned pretty soon afterwards. Also be careful not to overtighten that long bolt through the oil pump and squish the gasket, and don't pry against the aluminum pump body, use the square chunk of iron engine block right next to it. R&R of the oil pump on this motor is not fun. (edit: see here)

Interesting but I guess kinda not surprising to know how much of the juice goes to accessories vs driving -- I assume this was calculated over time for in-town driving? At low speeds, with not much wind/road resistance and plenty of regen braking, the numbers make some sense, even as odd as they are....

+1, want to watch out for too much noise or draw from these as they are also notorious for melting the fusebox when they pull too much current, esp if the connection at the fuse is iffy. 35A is too much; I have wondered about putting in a 25A fuse because it melts the box before the fuse blows. The alt is 55A; think about using all of that fuse's capacity, it's well over half the total alternator output....

^lulz.

The big problem is the cowl drains getting all clogged up as well as the blower box drain. If they aren't all gooped up, they work reasonably reliably on 700s. Usually you really have to blow them out carefully. All the detritus in there also holds moisture, which greatly increases the humidity generally, which usually makes for squeaking, corroding fan motor moving parts.

Theoretically, maximum alternator output is 55A, at minimum full output RPM...like 1800+ (engine, not alternator) RPM, if no belts slip, with the right phase of the moon with brand new perfect wiring on a brand new car

2 or 7 series the belt wrap isn't excellent for the fan or Alt, accessory bushing dealies are often all dried up worn out junk, and at least with the gas Volvos, the Roulands or "Volvo" (I suspect the same) are 9.5mm width with the correct taper and actually grip the belt pulleys properly. The 10mm contis don't quite grab properly.

Theoretically, the accessory bushings extend belt or accessory bearing life, when they aren't all dried up junk, though one would imagine that unless on a cool weather car with zero oil leaks with them changed out or flipped position every other belt chang, more often than not they have the opposite effect.

Many modern diesel engines have a power pulsation/vibration dampener on the alternator pulley itself, which is quite logical; large reflected moment of inertia on the alt (or fan, but alt especially), with a heavy rotor and ~4:1 pulley size ratio, diesel engine with strong compression/power pulsations on long stroke heavy engines. Of course, these are largely to improve belt/other accessory part life. Of course, more often than not, the pulse dampener itself prone to failure. Usually they are a sort of rubbery/ratchet contraption, which has a small space in which to live within the alt pulley. Has a profound effect on how smoothly the belt(s) run when it actually works.

Benz solves this problem on later engines with a shock absorber and heavy tensioner. Expensive part when it wears out, not rebuildable on later ones, but often lasts the longest.

Volvo stuffed the already undersized accessory bushing dealies on the diesel with less than great belt wrap or bracketry...
...not to mention finding the correct # belts through the dealer or set of correct roulands for the diesels was always a PITA. I'm not looking forward to this.

It has a pretty versatile onboard energy display monitor.

No leaks please.:)
 

Great stuff. Will follow this method and do it your way. What`s the torque specifications on the bolt that goes through our oil pump housing?
I cant have my gasket messed up :).

940 tdi auto 1995
 

hi i tried a gates belt but it did not last long . the genuine belts are better build and slightly thicker dimensions only very slightly . but alternator belts don't seem to last long enough on my engine .20000 miles max before signs of wear as in photo . i think other things are wearing a bit in this area now but with 222000 miles now .so hope the gates belt serves you better than mine . keep us informed of progress.

You are right about the Volvo belt because I`ve been torturing this oem belt for such a `long` time, not caring much that it already showed signs of wear 2+ years ago! I did care but was always hesitant to mess with the alternator. Had to tighten it a few times before... I did not use the right method but the belt itself held up nicely and never broke (yet). It even survived the fact that it was slightly misaligned (thanks to bad ps bushings) for at least 6months.

Wondering if a pulley with surface rust could be pushing yours towards the regular premature death. Mine also has some minor surface rust on the pulley but will confirm this after the belt comes off. Is there a suggested treatment for when this happens to be the case?
Chemical removal or gentle sandpapering?:) idk

Sturdy Volvo OEM alternator belt #966894 vs Gates belt
 

Well, I had a chance to sneak out of work, so....
the new Gates XL 7300 belt is on. Using the suggested method, I think I got everything set correctly, taking special care not to over-torque the bolt that runs into the block. It was easy to spot&use that square-shaped `nipple` on the engine block in order to stay safe with the heavy duty flat pry bar. (The aluminum housing looks fragile and the lower rad hose is relatively close too.)
It worked nicely.
Result is better than with my previous tightening(s). The belt squeal is gone. Time will tell if Gates is great or not; but it IS better than this bad condition oem belt I had on. omg.

The fluctuation of the Volt-gauge is not yet gone though (mostly caused by the heater/blower being ON. I started hearing a stupid crap noise from somewhere behind the glovebox area. Kind of hissing I think. Not sure what it is...long ago it was heard Only when blower was set to windshield position... but now i hear it in All positions. Even when the big knob is turned into 0 (zero). Sounds like it`s still blowing air/heat or there must be something going on. (next project) It`s stressing me out and I truly hate it. (At least the heater works, blows hot air nicely.)

The polished surface of the pulley shows where the old belt ran. Because now the new (wider) belt just can`t sit all the way down in the deep grove, it actually runs on the rusty area that the crappy belt wasn`t touching at all, for long years. I did not clean the rust off, let`s see what happens.

The Gates belt actually runs `on the top portion` of the pulley. My pictures well illustrate this concern. The Volvo belt ran differently than the new one. I`ll keep my eyeballs on it, surely I will have to retighten the new belt in the future.
For now, the `top` of the new belt sits literally `higher` than the edges of the pulley. As belt wears, it should sink down...?:) (New belt looks finely seated on the bigger pulley. That pic shows the worn Conti steering belt, also the ac belt missing)

Part 2, MACRO shows disintegration
 

Inside and outside, toast.

That belt was done for before it sunk to the bottom of the V.
All is well.

Don't be surprised if you check tension in a week or so and have to tighten it a bit, they usually stretch a bit in the beginning.


Re.noise
if its air in the vac pipes;
Vac supply for the whole climate cluster comes in the right side of the dash i think. if none of the vent doors work and you have no temp control(with the non computer system at least) it's probably that line. On the other hand, if one of the air motors has ruptured, there should be a way to keep it from getting signal.

blower motor noise;
Its always on a little to keep the bearing form seizing if you don't use it for awhile. simple test, reach up in the passenger footwell and unplug it.