Awful engine noise, Volvo 940
 

Not my car but one that I've been talking with somebody about, its a 940 with 105k miles. It makes this random screeching/howling when it idle.

I think most redblocks do it eventually, mine did. It's a loose belt. While it's doing that spray a little water on each belt one at a time. When the noise stops you'll know which one it is. Try tightening it and if it still does it then the rubber bushings in the support brackets are cracked, split or distorted, and that prevents you holding a good adjustment. They're pretty cheap
https://www.rockauto.com/en/catalog/...+bushing,11651

Most likely a belt, or a pulley, nothing serious. If these miles are real, should be a good find.

I'm surprised that Rockauto has Volvo parts, I thought I'd have to go with FCEuro to get stuff! I would test that myself but the cars a few hours away from me, and the owner isnt very familiar with cars from what I understand. If I were there I could probably diagnose it.

If its just a belt would it survive a long highway drive?

Sure it would if it's just a belt but make sure it is the belt and it's not really cracked, etc. Also, make sure the miles are right. What year is this car? Keep in mind '91-'92 740/940 speedometers are really bad, rarely survive. I'd run a Carfax to see the miles record besides evaluating the car's condition. A Red Block with 105k is barely broken in...

The owner said they'd take it to a mechanic so I'm waiting on that. The year of the car is a 1995, I dunno if it has the Japanese Yazaki gauge cluster or VDO. The owner hasnt driven it much so I dunno what gauges work and dont.

Good idea, check for cracks. If one of the belts is cracked and you tighten it up, it's more likely to snap on you sooner.

its hard to tell in that video, but it does look like the alternator belt is vibrating something fierce, which suggests its too loose.

as Moe said, the rubber alternator mount bushings should be replaced along with the belt, otherwise the alternator sits at a slight angle, and the pulley will eat the new belt. IPD sells poly bushings that will hold up a lot longer. When the belt is off, spin the alternator pulley by hand, make sure its smooth, and has no excessive end play or wobble, otherwise the alt bearings are shot, and its time for a new/rebuilt alternator. if you can rock the whole alternator perpendicular to the direction of the tensioner, then for sure the bushings need replacing.

That could possibly be the case, the car did go through a fresh battery according to the current owner. If the alternators that worn out I dont think the car would make it very long without a back-up battery. Thanks for your input though, along with the others who've commented here.

as long as the battery light on the dashboard comes on when you turn the key on, and goes out when you start the engine, the alternator is at least trying to charge the battery if its dim and/or flickering when the engine is running, then its weak and on its way out. a quick simple test is voltage readings when the engine is running, it should be around 13.6-14.2V.

'95 don't generally have bad speedos. But based on all the other info I seriously doubt the 105k miles. Volvos with 105k are pristine. Post the VIN# and I'll run a Carfax on it, may clear up the mileage question.

Thanks for the offer, I would request the VIN but the owners been very difficult with my questions, it took a few days and a bit of prodding just to test the heater/AC, which do work but the ACs low on charge. The car was towed to its current spot for what its worth, and its hardly been driven.

Theres a few other faults if they help indicate the real mileage:
1. Aluminum pipe/hose underneath the car has fallen off, I THINK this is the hose that goes from the airbox to an outlet on the exhaust.
2. Neuteral Safety switch is bad, so the car wont start in park.
3. Outer blinker light lense is broken.
4. The car was mostly driven to and from Oklahoma from Kansas, which leads me to question the mileage myself.

that alum hose serves no useful purpose except perhaps in very cold weather, however if you live in a place like California where they smog test older cars like these, it has to be present.

Thats true, in the past I yanked it off my 240s and cleared out the airbox just so they breahted better, and to keep the MAF sensor or what not from melting (I forget the part).

yeah, its pretty common trick to wire the flap thermostat closed, then secure the hose in place so it passes smog. they have never removed the air filter or looked under the airbox, just what they can see from topside.

True, I found baby jar lids to be effective airbox caps myself.

For now this might be my last update on the car. I havent heard back on the VIN. I explained that Volvos are known for buggy odometers, and when I asked if the guages in the car worked the seller picked up a bit of an attitude with me.

Well, not surprising. I am pretty sure based on the info you have shared that this thing has much more than 105k.

You're probably right, I never did get a shot of the dash to verify it let alone a vin, and the owners strange reaction of course. I'll look elsewhere for now.

Thank you for the carfax offer though, if I find another Volvo I might take you up on that offer.