Hi,

My 89 740 has a swirlling noise coming from the engine when it's running and it dosen't stop. I asked my father and he said it might be the belts, and if I put a little oil on them that it will stop , but i'm not really sure. Any suggestions

Don't ever put oil on belts. Oil is detrimental to rubber. Put some belt dressing on. If the noise goes away, you know it's time for new belts. They tend to get glazed where they contact the pulleys and start making noise. This is common. I've experienced this on my 87 760. Consider the noise to an early warning system indicating that the belts need replacement.

/// Not only will the noise stop but all the functions that the belts provide. The only thing you can put on the belts is "belt dressing." Belt dressing will get several days or weeks along before you have to replace slipping belts. Be sure that the noise isn't the fan clutch assembly. The noise may be normal. I do not have you model but I wanted to stop you from putting oil on the belts.

Belt dressing is availableis spray cans. Belts work by bulging the sides of the "V" where the belt is bent around a pulley. As the belt wears the "V" is worn away until there is no bulge. (non serpentine) You cannot improve V belts by tightening them.

There are other causes of noise but since I don't have a 700, I suggest you check and repost if you do not get help this listing.

Is the fan clutch engauged all the time. Because this noise is heard whenever the engine is running regardless how long it's been going

/// This depends on the model. I don't have that model. The bearings in the clutch probably would make noise all the time if they are bad.

I wanted to stop you from putting oil on your belts.

Check the fluid level in the power steering pump. You can eliminate the alternator and the power steering pump as the noise source by loosening the adjuster nut and allowing the belt to slip one one then the other.

I don't remember my first post but "V" belts work by bulging the sides of the "V" as the belt is pulled around the pulley. Belts do not stretch with age. They wear out from the inside. You cannot improve the grip by tightening them. Belt dressing only buys you time to get them replaced. You can get one or two weeks or more until better weather or until some other situation improves by using belt dressing. It might also kill the noise if the belts are the source. Might not!

if the fan clutch is failing when you rev the engine it will sound like a whooshing sound but this noise is mainly at higher engine speeds. the air conditioning compressor can make noise (especially if the system is not charged), power steering pump can make noise, basically anything that is driven by the fan belts can make noise. Check the condition of your belts if they are worn (any cracking...) replace them, if not you can try tightening them (they will stretch over time) the easy thing is to replace the belts if you suspect they are old/worn. Belt dressing may help, but as it is temporary why not just replaced them, they aren't that expensive or hard to replace. To check the clutch fan make wiggle it and make sure there is no play

(side to side/up and down) if there is play the fan is wearing out.

Hope this helps