1997 850R FWD Bearing

[sportracer]

Last October I was on a short roadtrip to Michigan. On my way there from Chicago I started to hear a distinct rumbling sound coming from the front of the car at highway speeds. I immediately though it was an exhaust leak since I have never replaced it since I bought the car new and then the car had about 185-K miles. I am a bit hard of hearing from my left ear so pinpointing the exact source of the noise was difficult at best. Prior to that, the traction control and Abs warning lights in the instrument panel had been coming on and off intermittently though I did not experience any braking issues at the time.

From then on, the car was mostly driven in town and below 50 mph so the noise was still very subtle, though still present. I had by then inspected the exhaust and CV-boots and everything looked normal. Then I noticed that the traction control and abs warning lights were coming on more frequently, but I still had no breaking issues. I topped off the brake fluid slightly but nothing out of the ordinary. Then, around March, the noise became increasingly louder from the driver's side and was now noticeable at 35-40 mph. I thought I had transmission problems, but the fluids all looked fine, but I avoided driving the car other than for running errands in town. I proceeded to inspect the left wheel brakes and noticed some oily liquid on the inside of the front driver wheel. One the wheel was off there was a similar but dirtier residue covering the rotor, and the caliper. I pulled the caliper off and noticed the inner break pad was coated in an oily substance. I then thought that somehow the brake fluid had leaked onto the pad, but I had not seen a significant loss in brake fluid at the reservoir. I then thought that perhaps the noise was coming from the oily pad rubbing on the rotor so I pulled everything to clean it up and then I discovered that the brake caliper piston had a few deep scratches along the outer surface. I pulled the lip seal off and proceeded to remove the scratches from the piston using a very fine emery cloth paper. I could not find any damage to the piston seal or amy source of the scratches in the caliper. SO I put every back together once I cleaned everything and hoped that was the end of that.

It turn out I was wrong ,and the noise was now louder and now I was almost certain that the break fluid that leaked out of the caliper somehow got into the sealed bearings of the hub assembly and caused the bearings to fail. Could it be that the lip seals i the bearings are not brake fluid-proof and will deteriorate thereby resulting in contamination of the bearing.

Right now I am about 90% sure that the driver's side bearing is bad and I've driven the car and jerked the steering so that I load the passenger bearing and the noise seems to momentarily disappear in that process. I would be more sure If my hearing was better from my left side, but given the detailed events that I described, I wanted to see what the general consensus was from possible readers and wether there may be other tests/inspections I should try before I embark on this potentially costly repair. I am particularly interested in how the warning lights may have or not contributed to the problem; since they are still coming on even after the piston repair, which has been proven to be successful. Thanks fellow Volvo Enthusiasts.

[Ozark Lee]

The ABS issue is distinct from the other bearing issue. Your ABS module is failing - it happens to all 850 modules after the '95 model year.

Can you detect any looseness in the hub? If it is loose the hub (bearing) is bad for sure but I have had them roar without the bearing feeling loose. One trick I have heard of is to jack up both sides and spin the wheel while holding the spring. The noise and vibration will be obvious on a bad bearing,

...Lee

[FCPEURO]

+1

You can repair the ABS module yourself if you are good at soldering. Otherwise send it out.

[whoa]

Have you considered that the oily substance might be the bearing grease?

[ChaddGostas]

I contacted midwest abs from a post here. The guy sent me a new abs module, he said it was not cosmetically perfect. I could not tell ! no kidding. ever since my abs light only comes on occasionally. I know it is the electronic part of my ignition switch.
I know this because I bump the steering wheel and everything works perfectly. One day I decided to drive with the steering wheel cowling removed and wiggled the wire connected to the switch and all worked well.
Symptoms were:
no speedometer,
no lights,
no ding when I started the car,
no seat belt lights
abs/tracs off light was constantly lit

I bump the steering wheel, kinda hard, and everything goes perfect.