My 1993 240 has a nasty intermittent screech when driving. When it screeches, if I stop the car the screech stops. I have turned off the blower motor and a/c during the screech sessions and it continues. Checked the tensioning on the belts and they appear ok.

Where should I start?

Thanks

 

is the screech under the hood or from under the car? could it be one of the wheel brakes? if a pebble or something ets stuck between the rotor and the backing plate it can make some nasty noises. ditto sticks or brush can get stuck between the car and the drive shaft, and make a speed dependent noise.

 

Coming from front of car. Hard to tell if under car
Or under hood? Stepping on brakes does not make noise
Better or worse.

 

does the noise change pitch/sound with the engine RPM's or road speed? like, next time its doing it, put the car in neutral, and let the rpm's drop to idle while still coasting at whatever speed you're going.

 

Let me try your suggestions and post results, thanks

 

Additional information - putting car in neutral and coasting did not make the intermittent screech / whine go away.*Screech /whine does not change with increase or decrease of engine rpm.

 

ok, so its probably NOT engine related, so its likely a wheel/brake, or something scraping the drive shaft. I think I'd jack up each wheel (one at a time) and spin it, see if you feel anything scraping, and investigate.

 

How difficult is it to replace the driveshaft center support bearing? I want to replace this to try and see if it eliminates the whine.(looks like it needs replacing, spring looks messed up)

How does the universal come apart?

Thanks

 

the center bearings usually make a grinding or thumping vibration when they are shot.

I'm not 100% sure I remember how you get them off, I think you unbolt the front half axle from the back of the transmission, and unbolt the bracket that holds the center bearing in place. I do know, you should always replace the rubber donut it sits in as well as the bearing itself.

looking at the parts diagram, the center U joint is attached to the rear shaft, and has a spline thats slid into the front half just behind the bearing. maybe you unbolt the rear shaft from the differential, slide it out of the spline, then pull the bearing off. parts diagrams...



and this shows a couple variations on the driveshaft



I believe yours is the upper one, parts #13, 9, 14, mated to the lower one, but I think the center bits shown on that 2nd diagram are 740/940 style. #13 bolts to the back of the tranny, and #18 bolts to the differential...

 

I have had to replace this bearing on both of the 240s we have in the family. They seem to go bad at around 185k miles as both of our cars had that mileage when I had to replace them. You need to drop at least the front driveshaft. The rear just slides into the front. Before you separate the two, make sure you mark the alignment between front & back.

The bearing is pressed onto the shaft. You need a puller to get the old one off and a press to install the new one. You can tap it off/on with a hammer & drift (time consuming). If you tap it on, make sure you tap on the inner race.

 

Ok, -so it turned out to be the ................brakes.

When I was checking the wheel bearings, etc. the brakes looked at about 20% on the front and 30% on the rear so I changed them out and the noise is now gone!

Thanks for all the help here to try and eliminate this!

 

yeah, life is too short for bad brakes.

FWIW, my latest brake job, I had Brembo rotors all the way around, but had the wrong front pads (thought they were for my 945T, but instead they were for my daughters 244), and all I could get that day (hey, car was on stands, taken apart), was PBR semi-ceramic pads instead of the Volvo blue-box pads I've always used... took me a bit to get used to them, but now I'm really really liking them. The initial bite is softer than the Volvo pads, but the braking is smooth, progressive, and with just a bit of pedal effort, very strong. Supposedly the pads wear out faster, but the rotors last longer, which is probably a win. They make a LOT less dust than the factory pads, so my front wheels aren't black. That makes it a win-win.

 

Been using AutoZone pads for my entire fleet(4) of 240's for many years. AutoZone warranties the pads for life, so I just bring back the old ones and they give me new ones. Probably gone through dozens of pads in the past 20 years!

 

hahaha, thats like my son and rock climbing shoes and REI. He can wear out a pair of the most expensive rock climbing shoes in under a year. I think hes' on his 5th or 6th pair now.

when I say wear out, I mean COMPLETELY shreaded, soles flapping in the breeze.