ABS unit is making a wierd sound... - PeachParts Mercedes-Benz Forum

Diesel Dan · #1 07-17-2006, 03:52 PM

Hello all!
I have noticed recently that when I apply the brakes, I hear a "Clicking" or "ticking" sort of sound that seems to be coming from the ABS unit in the front driver's side part of the engine compartment. Does anyone know what this sound may be? I assume it's not supposed to do that, but I haven't owned the car long enough to be familiar with all it's sounds. Do I need to replace or otherwise repair the ABS unit?

Thanks,
Dan

TX76513 · #2 07-17-2006, 04:40 PM

Have you physicaly inspected your front brakes? I have not been around an ABS that makes a ticking sound mostly a vibration or groaning sound. Thinking of clicking or ticking as a metalic tinny sound.

Diesel Dan · #3 07-18-2006, 10:41 AM

Thanks for the feedback on typical ABS sounds. The sound I hear is not a groaning or vibrational sound; it's more like the sound an engine would make when cooling off after being hot, except louder, and more percussive. Like a "tacka-tacka-tacka-tacka" kind of sound. I haven't really inspected the brakes themselves yet, so I'll take a closer look at the caliper/rotor/pad assemblies and see if there is a problem there.

Thanks again!

skiier3_9 · #4 07-18-2006, 05:40 PM

How freqent are the "tacka" sounds? Like >1/sec? If this is the case its probably the ABS pump making the noise. You can get a automotive stethescope or just use a screw driver held up to your ear to CAREFULLY listen to various components while you hear the noise to verify.

The ABS/ASR pump on my car would make a "tacka tacka" clicking noise on start up and following any ASR/ABS engagement. I found that the pump was bad and replaced it for ~100 (used eBay purchase)

Diesel Dan · #5 07-28-2006, 12:37 PM

The sound is continuous and sounds sort of like a kid running by a picket fence, while holding a stick on slats so it makes a "tacka-tacka-tacka" sound. How's that for a vintage image?! It's like a scene from a "Little Rascals" episode! Now I know I'm getting old!

I can't identify the exact location of the noise using any stethescope-type tool, because it only happens when the car is in motion. I'm not a stunt man!

If the problem gets worse, affects the braking performance, or just really starts annoying me, I suppose I could replace the ABS pump, and hope that fixes it.

Thanks!

Diesel Dan · #6 09-20-2006, 10:09 AM

Any other takers on this one? The noise only happens when the brakes are being applied and the car is in motion. The harder I stomp on the brake, the louder the sound gets, although the sound will occur to some extent even under light braking. Another thing is that the sound is worse when the car is cold, and better after it warms up. I've heard something about an ABS relay - would the relay make a loud noise, like a "tacka-tacka-tacka" noise? Oh, one more thing... the ABS light on my dash is not coming on, except briefly during startup, which I think is normal... although it seems to stay on longer than the other lights...

david s poole · #7 09-20-2006, 11:47 AM

had this same prob once on a late 80's bmw which turned out to be the abs unit.pulled the two relays to prove it [which turned on the abs light].replaced with used one and fixed the problem.those early models were pretty solid with few problems.

Diesel Dan · #8 09-20-2006, 02:12 PM

Quote:

Originally Posted by david s poole

had this same prob once on a late 80's bmw which turned out to be the abs unit.pulled the two relays to prove it [which turned on the abs light].replaced with used one and fixed the problem.

Is there a way to disable the ABS pump, but still have normal braking - just minus the ABS feature? I'm pretty strapped for cash right now, and don't want to put down $250 on a used ABS pump. But I would like to eliminate that awful noise. If I pull the relays, would that do the trick? If so, what do the relays look like, and where are they located? I promise, I'll reactivate the ABS one day!

Thanks!

david s poole · #9 09-20-2006, 03:17 PM

yes simple undo two screws holding black cover on under you find two relays pull them both and voila!

Diesel Dan · #10 05-29-2007, 10:58 AM

As it turns out, the noise was being caused by the fan coming in contact with the radiator, and/or fan shroud. As I braked, the engine would shift forward just enough to make the fan blades slap against these other parts. I verified that this was the issue by slamming on my brakes while driving in reverse, and hearing no noise. Also, my fan and radiator are all torn up. My plastic fan blades are all chipped and worn from this problem, so I just cut them down a little further with some tin snips, and repositioned the shroud a little bit, and voila! No more noise.

I finally put 2 and 2 together after reading a post on this forum by someone who had a similar problem. I just love this forum!

Arthur Dalton · #11 05-29-2007, 11:02 AM

You have a collapsed motor mount.

Diesel Dan · #12 05-29-2007, 12:16 PM

Quote:

Originally Posted by Arthur Dalton

You have a collapsed motor mount.

That would be a logical conclusion, but I just had my motor mounts replaced! Next time I take my car to the shop, I will point out the issue to the mechanic who replaced the mounts, and ask him why my engine would still be shifting.

Arthur Dalton · #13 05-29-2007, 12:43 PM

Have him check the rear mount [ tranny mount] too. That is the third motor mount. You may not have done that when you did the r/l ones..
There is also a guide rod/strut to check...