Noise coming from fuel tank (broken baffle)?

[fchristensen]

Hi

My SL500 (2003) has a clunking noise when breaking or accelerating and it's coming from the fuel tank. I have been reading up on other MB forums from around world and it looks like other people have had this problem too. All research leads me to believe that this is due to a broken baffle that is floating on top of the fuel.

The car is out of warranty. However i have read that other people have taken their cars to the MB dealers insisting that they fix the problem. You have to excuse me i am new to Mercedes' and their servicing policies, but this seems like a longshot to me? Is it worth trying? I know the alternative is pay aprox £1,000 for a new fuel tank + fitting which i would like to avoid obviously.

Any tips from you experienced MB people out there would be greatly appreciated.

Many Thanks

Fred

 

[television]

Not an easy job fred, I know one guy that removed the pumps etc and with a pair of tongs wound the loose baffle up and pulled it out.

MB will pay nothing towards this, even though it is their fault.

The fitting is an horrendous job, even worse on the AMG owing to the extra work involved

 

[fchristensen]

Hi Malcolm,

Thanks for your quick reply!

Do you know any good mechanics that would be familiar with this issue who can help me? I don't want to take it to MB as they will charge me £2k + to do this.

Any advice?

Thanks again

Fred

 

[television]

Where are you in the UK please

 

[fchristensen]

London ( Kingston - Upon - Thames) but willing to travel anywhere to get it fixed for an ok price.

Thanks

 

[television]

Then willow132 a member here and he did one late last year, send him a PM and he will sort it out for you at a good price

 

[fchristensen]

Thanks Malcolm

I have sent a PM to willow123.

 

[bedhead2d]

same problem with rattling fuel tank

I seem to have now got the same rattling problem with my SL500 fuel tank.
Can you please tell me what it cost you approx to get this fixed, if you did?
I am rather nervous about the quote, especially as I was planning on selling the car soon, so any help appreciated.

many thx

 

[television]

The dealers charge some £2k for this, I would have a word with member willow 132 who is a mobile indie

 

[W1Z]

After a couple of years of trouble free motoring, I too have this problem and it seems that Willow123 is no longer on the site. However, after a bit of net searching I found two useful things I thought I'd share in case they are of use to someone else. The first is a set of instructions for fixing this problem. Basically, it's a way of tying the baffle down so it no longer rattles without taking the tank out or replacing it.

The second is someone I found on eBay who'll do it for you for £300 (negotiable).

Here's the post I found, credit to UKSilverArrow (the original poster).

If you have a loose fuel tank baffle it can be fixed. I can't guarantee it will last forever but if like me your car is out of warranty and you weren't lucky enough to find £1,500 in your jacket pocket that you'd forgotten all about then you may want to do what I did.

I've searched all over the web for fixes for the problem and found very little, not even a definite description of what the baffle looks like.

So here's what I did, all in it took about an hour and requires no special skills other than pure cunning and/or determination to avoid the dealer.

All work is undertaken in the boot (trunk) with the roof closed and took around 1 hour and is best done with as little fuel in the tank as possible, my gauge showed a quarter tank.

1. Remove the boot seperater, 4 press studs, 1 either side and 2 on top and lastly 2 bolts where the hinges attach to either side of the boot, these will be under small plastic covers which just unclip.

2. Lift out the boot floor.

3. Remove the carpet cover at the back of the boot, there are just 2 screw fixings under plastic covers near it's base, it's not attached at the top just wedged in. This panel is overlapped by the boot side panels but only by half an inch so can be bent a little either side and coxed out. If you're uncomfortable with this you'll have to remove quite a lot of the boot linings to get the side pieces off but really it's not worth it.

4. Now you'll see the bulk head covering the fuel tank and the cut out at the top for the fuel gauge, good news you'll soon be seeing the mythical baffle. The sender is slightly covered by a fixing strip that the boot seperater attaches to.

5. Remove the plastic trim strip, again just 3 push clips.

6. The sender is a boyonet fit in to the top of the tank and only needs a quarter turn to remove, but make sure you unclip the sender wire first.
The only easy way to remove it is to fashion a makeshift tool to locate in two holes in the top of the sender. If you're looking at it you'll know what I mean, I used a piece of quarter inch tube 6" long with 2 screws welded on one end approx 2" apart (looks like this F). You may be able to avoid this depending how tight your sender has been screwed in by just jamming a couple of bolts in the holes and turning by hand. Mine wasn't that tight so I may have been able to avoid making the tool. Make a mark on the tank and sender to help when refitting it as it only works in one position.

7. The sender comes put pretty easily and now you'll be able to see the baffle. A small torch will let you see clearly and poking a piece of bar in and proding the baffle will let you see what causes the banging and why. The baffle runs east/west through the tank and is about 3/4 the height of the tank. It's fixed at the bottom and should be fixed at either side (end) and this is where the weld has failed allowing the baffle to hinge front and back (acceleration and braking) knocking on the wall of the tank until the fuel stops sloshing.
There's no way to remove it without cutting the tank in half, I'd guess it's about 36" wide by 12" tall. The baffle kinks about 45 degrees near it's top forward to the front of the car and it's this edge that hits the wall of the tank.

8. So how do you fix it? Well there are a few slots cut along the top of the baffle where it kinks forward so here's what I did. This fix involves drilling and 5mm hole in the top of the tank just above the sender so I appreciate many of you may not want to do this so you'll need to be very creative or a damn site smarter than me (not so hard) to work out another way.
I took a regular coat hanger and just bent a hook at the end, I actually doubled up the wire by folding it in two first for a bit of extra strength. You can work out lengths and angles by first pushing the wire through the sender hole and locating one of the slots, there were 3 to choose from and you have good access and vision this way as they're practically level with the sender hole.
I managed to get the hook in one slot and out of the one next to it for a secure hold. Once you've worked this out repeat this but push the wire through the hole you drilled. The hole has to be above the sender to avoid fouling it when it goes back in. A good idea is to use a piece of rod or anything you can push through the slot to pull the baffle toward you slightly to give some tension to the wire hook. Then all you need to do is bend off the wire where it exits the hole, this was where doubling up the wire worked out well, then tape in place. I used a little sealant in the hole to seal it fully.

9. Replace the sender, check that it works and refit the boot parts.

10. So far it works fine, no knocking and the car hasn't exploded, not even once.

I hope this helps some of you guys out and saves a few pounds/bucks.


P.s if you get stuck because I wasn't clear enough let me know.

 

[andy@pcd-ltd]

Hi im still on here my name has een changed from willow132 to Andy@pcd-ltd as im a forum sponsor now

 

[W1Z]

Thanks Andy.

Actually, my son came up with a possible clever solution to this problem, I'd be interested to know what you think...

He's a chemisty grad and at uni they use super-powerful rare-earth magnets made from neodymium.

These magnets are amazingly powerful, you need to wear goggles when handling them as they can fly together with such force they can shatter the metal. Two magnets the size of a box of matches would be impossible to separate by hand.

His idea, was simply to attach one to the outside of the tank when the baffle has come loose. It is presumably made from metal, so it would stick to the tank and that would be the end of the rattle!

Sounds like a great idea to me, but you'd need some inner knowledge of the tank to know where to postition the magnet. Any ideas?

 

[television]

There have been links on here showing the insides of the tanks and exactly where the loose baffle is.

 

[peterwhayward]

Thanks Andy.

Actually, my son came up with a possible clever solution to this problem, I'd be interested to know what you think...

He's a chemisty grad and at uni they use super-powerful rare-earth magnets made from neodymium.

These magnets are amazingly powerful, you need to wear goggles when handling them as they can fly together with such force they can shatter the metal. Two magnets the size of a box of matches would be impossible to separate by hand.

His idea, was simply to attach one to the outside of the tank when the baffle has come loose. It is presumably made from metal, so it would stick to the tank and that would be the end of the rattle!

Sounds like a great idea to me, but you'd need some inner knowledge of the tank to know where to postition the magnet. Any ideas?

I'm no chemistry grad myself but would the magnets power not be diffused over a large area such as a tank, and in any case as the baffles are welded to the tank and are therefore part of the tank would the polarity not be wrong?

 

[W1Z]

I'm no chemistry grad myself but would the magnets power not be diffused over a large area such as a tank, and in any case as the baffles are welded to the tank and are therefore part of the tank would the polarity not be wrong?

There wouldn't be a polarity problem as the baffle isn't magnetised, but the diffusion could be a problem for sure. There would still be a greater localised field but given the force of all that petrol hitting the baffle under breaking/acceleration it might not be enough to prevent it from hitting the sides and making be noise. From the description, I guess the magnet would have to go at the front of the tank where it could grab the top edge of the baffle as it hits the front wall, but 350+ kg of petrol hitting a metal sheet at around .5 of a g is a hell of a lot of force. And the reason the darn thing breaks in the first place of course.

 

[Alex Crow]

I would think that special foam stuff for tanks used in extreme conditions (eg competition) would do the job, perhaps that is what the ebay seller does.

 

[stevobow]

There's an easy DIY fix for these tanks that requires a £5 spring... There's a 'How To' somewhere, I've got to find it because I've got to do mine.

You take out the sender unit, attatch an expansion spring to it (7 inch I think) and hook it over the baffle inside the tank. The spring pulls the baffle away from the side of the tank and gets rid of the clanging noise

I'll post a link when I find it.

 

[stevobow]

Hope posting a link to a forum is allowed...

http://www.benzworld.org/forums/r230-sl-class/1295215-sl500-noise-rear-interior-wall-gas-23.html

Page 23 gives you a pic by pic guide how to do it

 

[Makhecha]

I have a 2003 SL500 and have experienced the two main problems with these cars. 1 . the leaking boot which required complete new boot seals to repair the leak. This must be done otherwise the PSE pump will blow causing a complete central locking issue. I also have had the baffle break away in the fuel tank. LUCKY LUCKY for me I bought the car only 7 months ago and had a few other small problems before this happened. Dealer has made good on both boot leaks and replacing the fuel tank. ADVICE ONLY BUY THIS MODEL FROM A MERCEDES DEALER AND MUST GET THE WARRANTY.ASK TO SEE THE SERVICE HISTORY AND ASK TO SEE IF THESE PROBLEMS HAVE ALREADY BEEN RESOLVED.

 

[Gkinghorn]

I preferred the solution the guy did with the broom handle.... Brute force and ignorance seemed to be the order of the day ...

Wonder if the guy ever took MB to court?