2003 ML270 - Buzzing sound under bonnet

[dvb247]

My wife's ML was buzzing away on the drive, didnt stop until I took off the battery live, the buzzing is coming from the square alloy 3" square brake thing just to the right of the engine near the radiator.

Very sure it's that it's something to do with brakes, 4 brake lines come out the top of the buzzing alloy square, very hot too!!!

Think it's going to be expensive

 

[Mercedes cozy]

best to post a picture of the item so we can identify it

 

[Bobby Dazzler]

Sounds like an ABS pump

 

[dvb247]

Can it be repaired?
What price are they?
Pic to follow

 

[dvb247]

 

[Bobby Dazzler]

My father-in-law got a replacement ABS pump for his Range Rover from a specialist breaker for £150 - no reason to believe the ML should be any different.

 

[gtvlusso]

Hi,

Yes it is the ABS puump. The relay for this pump tends to go bang, mine did the same thing - the pump will run on even though the engine is off. Pull the relay in the engine bay fuse box - can't remember the number off hand, but it is marked on the inside of the fuse box lid.

The cost for a new relay is £12 from a dealer.

Do this before you look at changing the pump as changing the pump can get expensive.

Also worth nothing that you will be able to swap one of the less important relays (e.g. rear screen demist) to test out the pump and have a drive.

Very important to get the pump off asap and let it cool for a bit too......!!!! Bad things **could** happen to the brake fluid!

 

[BlackC55]

+1 It will probaby be the realy at fault

 

[dvb247]

Thank you VERY much, if your right (and I think you are!!) the problem only seems to occur when my wife has her car back, think she wants to keep hold of my car
Can I ask a silly question, where is the relay/fuse box on the ML? as I need to get the part numbers off it, and replace it too

 

[gtvlusso]

Stand in front of the car:

Back right (passenger) side - it pops off with 2 clips (can be a bugger to get back on, make sure it is seated right).

Looks like part of the aircon unit - i.e. you will see a gas advice sticker on it. Essentially - big black plastic cover.

Look for 'ABS relay'

You can swap it with another of the same value that is not running a vital system for a quick test.

Very common for them to go pop.

 

[gtvlusso]

Here you go:

The relay noted in this picture is not the ABS relay - nicked the pic from another forum!

I think the relay number is K25 - should be a dark grey one.

 

[wobbly]

I seem to have the same problem on my W164, the ABS pump is buzzing when the engine is turned off.

Had a look, but only have a list for fuse location, not relays.

Anyone know the position of the ABS relay on a W164 ?

 

[dvb247]

Sorry wobbly I can't help with that but just a thanks for all the help, problem solved, I have replaced it but before it came I opened the relay, cleaned the contacts with a stanley blade and it solved the problem temporarily!!