W164 ML SAM module / water leak soruce

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thecolonel

Active Member
Joined
Nov 11, 2013
Messages
130
Location
Surrey
Car
ML (W164)
Hi,

not sure which section to post this in, so went for interior.

I recently bought an ML W164 2008 model, which back in June had a rear SAM module replaced after the brake lights failed I believe.

Something has been mentioned about water leaks and these modules getting wet and failing.

Can anyone advise on the source of water leaks (am I correct in thinking rear lamp units??) and what can be done to ensure occurrence does not happen?

Any pointers welcomed.......
 
I was told by a Mobilo technician that pointing a jet wash nozzle upwards will cause water ingress and result in SAM unit failure on the W164 ML. That was in response to the question "I fancy a W164 - what's it's Achilles heel?
 
Cheers Bobby, did your chap happen to mention where this maybe occuring with the water ingress? Or maybe where the sam unit is?

Thanks for your feedback
 
My c63 has just had this done also, when you say pointing upwards, do you mean from under the car or at the rear lights?

If the first, how would one go about cleaning under the arches to ensure no salt build up?

I was considering wrapping the rear fuse box/Sam in a bin liner to make it more likely to resist water, obviously this wouldn't be seen with the boot trim in place and although silly, prevention Is definately cheaper than the £720 cure I've just received!

Whether it was even water ingress that caused mine, or whether this will work is a different matter however!
 
where is the rear SAM module located exactly, once I find that I can probably establish the source of any potential leaks.

wrapping in a shroud maybe one solution, depending if the unit gets hot or not I guess.

any pointers on locations?
 
right I have found the rear SAM module for anyone interested on a W164 ML, although probably similar location for the range.

Its behind the right hand side inspection panel in the boot area, at the bottom of the wheel well recess - highly prone position I must say! there is an air vent just above it which is behind the bumper so would tie in with suspicions about the water ingress being from behind the lamp unit or under the wheel arch.

now to try and waterproof the area for the future
 
I made a comment a while back about these, as it looks like there is a cover missing, must just be a bad design, especially as this would appear to be an off road vehicle
 
Sorry to OP, forgot to reply, it is in fact on the rear right of the boot in mine, same I suspect with yours, it's essentially the fuse box I believe!

Let me know how you manage to shield it
 
The rear SAM is indeed in the rear right of the boot behind the hatch cover, but it is below the fuses you see, deep down in the recess (on the W164 at least). The usual reason the SAM gets wet is water ingress through the rear tail light seal gasket. This is apparently a known issue, it probably leaks on the other side as well but with no real consequences. Ive also heard of the rear window leaking but i guess that must be pretty rare.

My ML suddenly got probs after heavy rain, the back passenger door lock wouldnt open (the other doors would), the motorised boot release wouldn't operate at all, the middle brake light failed and I got the warning that the bonnet was open!

I plan to spray the SAM with WD40 and pack it in with sponges and paper to ensure that the rain doesn't get in. When I've got a bit more time (we're going on holiday in it in 2 days...) Ill replace the rear light seal.
 
The rear SAM was moved to under back seat in later W164. I have seen them with covers too, so I guess a cover was introduced at some point. They get warm, so need airflow, so putting in plastic bag is not so advisable.

Most Mercs have vents behind the rear bumpers (at the sides) that allow air exit from the vehicle when doors are slammed (so they shut). They have a flap over them allowing air exit but not in, however if you point a jet wash upward under the side of the rear bumpers water can go in.

This is very bad on W211/W219 which has navigation processor, TV tuner, Parktronic, Keyless go etc modules around there on Left side. We see a regular supply of dead audio systems because of those.

SL has stuff there (Keyless, alarm sensor, DAB tuner, Nav processor)
S class has DAB in a vulnerable place, although TV and amp also very near.
ML has rear sam on right side.

Water can therefore enter there on a ML, and from the rear light seal if rear light has been replaced and seals were duff and not replaced, and also a bad boot door seal can let water in too. I'm sure there are other ways but that is what we've seen.

Richard
 
This has just happened to my 2009 ML350.

The SAM unit actually burnt out whilst I was on the motorway, the car was stinking of electrical burn out.

I got all sorts of dashboard warnings, including the rev and mph counter going off.

Has anyone figured out the source of the leak? I checked the seal but it seemed ok. It might need changed anyway?
 
It's definately worth sealing the rear right lamp cluster from the outside with some black silicone.

Easy to make a neat job of it with a sealant gun and a wet finger.. Takes about a minute, once you've got the seal clean..

Not a fan of jet washes anyway, they seem to do more harm than good, and the inner wheel arches are plastic anyway, so don't need washing....
 
Water Leak in spare wheel well

just spent the morning trying to find were the water is coming in to my ML320 06 - firstly sucking up 1/4" water in spare wheel with vax - having removed both left and right side covers (right fuse box & sam) (left 1st aid kit) the fuse box and sam area don't appear damp or signs of any water ingress - from a watering can I poured water over side windows/light units and tail gate couldn't see any water coming in anywhere - focusing on the left n/s/r rear wheel arch, there is some sound proofing foam/spongy material which wraps over the wheel arch. This was full of water I don't think this was from my watering and I've dried it best as I can with the Vax. I'm no nearer finding were its getting in :confused: so going to have a chat with my local Merc dealer tomorrow.
 
Still can't figure out where the leak is coming from.

I've replaced the 3rd brake light at the top as this was broken and saw some water coming in there. That is now resolved but still water coming in the well underneath the fuse box.

Even mercedes don't know where it is coming from....!
 
Got a similar problem and it's infuriating! Feel like sleeping in the boot in the rain just so the source can be confirmed!
 
Hello Bolton26,

After seeing your post about your ML water leak in the rear right well, below the fuse board, did you find where the source of the leak was? The foam that covers the arch is soaking in my ML. I did have an initial leak through the brake light but this has now been fixed. Any info would be great.

Thanks.
 
Had the same problem, replaced left and right light seals and the 3rd brakelight. Dried the whole area and covered the surface with talc to see where the water was getting in. Both areas below the left and right lights are now dry but still water under the tool foam. Cannot work out where it comes in. Have removed 2 of the grommets at the lowest point, put a 5mm plastic grill under the tool foam the water gets in but drains thru the bung holes. I would like a fix but even the dealers do not have a 100% fix.
 
Hi topdown. Good to know it's not just myself with this issue. Thanks for the information too, if possible do you reckon you could post a photo showing what you have described? Much appreciated.
 
bung at bottom of enclosure

When this bung is removed, any idea where this water travels to? Does this bung just open up to the underneath of the car? If so, I think I will drill a small hole in the bung so any water that gathers in this area can trickle out.
 

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