Bad noises & metal flakes

[jcyuhn]

The wifey's 1993 300E 124.028 broke down on the highway today. Car has about 140K miles. Bad noises from under the hood. She limped it off the Dallas North Tollway to the nearest bar (she was in Addision - that's all they have there) and shut it down.

When I checked under the hood the engine was covered in small metal flakes. Everything else looked normal. All fluid levels up to spec, all parts appeared to be present and accounted for. Started it up and at idle it made a slight knock-knock noise from something on the serpentine belt - couldn't tell what - but it didn't really sound all that bad.

Any guesses? I don't have time to deal with it, so a local indy is getting the work. I'm thinking fan bracket bearing is most likely.

[scottmcphee]

You've got to be able to see thing that is worn down, or a hole, where the metal flecks came from... Unless some road debris flipped up into the belt and got chewed up? Rad and fan didn't touch did they? Bent blade? ... this is really curious.

[pawoSD]

Sounds like one of the pulleys is failing or something. Sounds like you're on the right track with the fan assembly.

[jwhughes3]

i concur - tensioner pulley.

[jcyuhn]

The tensioner is reasonably new, maybe a year or two old. So I doubt it's that pully. My bet is on the fan bearing. I could spin the fan by hand with the engine off, so it wasn't up against the radiator at that point. Doesn't mean the bearing isn't going out - I'm certain it is original to the car.

Will post a followup when I hear the diagnosis.

[jcyuhn]

Shop called. Fan bracket bearing. Right on schedule too - they always seem to go out at 150K, give or take 10. Almost replaced it as PM when I put a new water pump in the car last fall. Bearing felt OK, so I took the ain't broke, don't mess with it approach. Not gonna have any spare beer money left this week...

- JimY

[jcyuhn]

Dang, spoke too soon. The shop owner called me to chat, always a bad sign...

A piece of metal - possibly used to be a bolt, he couldn't tell - somehow got into the serpentine belt. Bounced around and damaged the fan and water pump pulleys. Then - get this - lodged behind the main crank pulley, grinding away at that pulley as the car ran. Hence the metal flakes distributed about the engine compartment.

He's removing the crank pulley this AM. He is optimistic we won't need anything more than a new pulley. Hope that's true - if the nose of the crankshaft is somehow damaged, I think the car is going to get parted out. A real shame, as this is a nice daily driver 124 sedan - everything works, good paint and interior. Until Tuesday the only problems it had were a slightly droopy headliner and mostly missing hood pad.

Can't find any missing fasteners on the front of the engine. Nothing has been touched under the hood since the water pump was replaced. Can't recall exactly, but think that was last Octoberish. The car has the plastic panels on below the engine compartment, so it seems unlikely that something from the road could get in there. Still, I guess anything is possible.

Why do I always have the interesting problems?

[jjohnv]

don't see how the nose of the crankshaft could get damaged with the pulley covering it and protecting it. you should be ok and its not a hard fix. just pull the pulley and replace the belts. I bet its still gonna cost you $1200 having the dealer do it for you.