Fluttering noise on acceleration

[DavidSoine]

The sensor on the diff is for ABS.

best,

Dave
87 560sl

[DanielG]

thanks for looking that up!

[DanielG]

Well, here is the latest. The current mechanic says that the rear axles need to be replaced and new bearings installed -- dry, cracked, rusted are adjectives used. Says the left one for sure, the right one can stay for awhile. Quoting $831 for new axle, bearings and labour (left side only).

I have been thinking about selling this car. Dealerships have offered a very low price as a trade, so if I trade it to them I am not inclined to do the work. I have not gotten a serious offer from advertisements in the newspaper (would probably do the work if selling to an individual -- or at least tell such a person ahead of time and reduce car price accordingly). Further, I hate to put the money into this work only to find that the noise persists (since the car probably needs this work anyway, its not one of those situations where you can make a deal with the mechanic that if it the noise persists you don't have to pay). Thoughts?

I'll let you know what happens.

[Richard1]

If $830 scares you now, then most definitely trade in, because it is only going to get worse in terms of big ticket repair items.

[DanielG]

$830 doesn't scare me -- I'm just (probably) not going to keep the car and the dealerships aren't going to give me more than they already offered, so I wind up losing more money! If I were keeping the car I would do it.

[Richard1]

Daniel, the dealers will give you how much for this..maybe $6k? If you are thinking of tossing or keeping, you may have to do the repair. No one in a private sale is going to want to pay you the sort of premium you could get for a low mileage, good condition SL, if there is a mechanical issue.

[DanielG]

Richard, the dealer, with knowledge of the noise is giving substantially more than the figure you note (and yet a lot less than what the car would be worth to you or me). I have shown the car several times to individuals some of which did not care about the noise (even though it is prominent and evident) -- the car shows that well. I am of the belief that the dealer would offer the amount offered even if the car was in showroom condition -- that is the nature of that business -- make money on the sale of their car make money on the purchase of your car. If you walk into a dealership to buy a car they figure they are entitled to make money on both ends.

I am neither new to cars or to Mercedes Benz. I know the value and I know how dealers operate. I guess I will ascribe the loss that trading the car into a dealership represents to the joy I have had in the ownership of that car -- it was worth the price, and it is probably worth it to leave this car before a series of major repairs, that will surely come due, sour that joy. The car has been costly but fun and I realized a long time dream of ownership of a 560SL. If anyone wants a beautiful 560SL for a very good price let me know quickly.

[Richard1]

Ah the 560sl....even with the costly repairs, best car I've ever owned. I tried to trade mine in for a new car...an audi s4 or something else...just couldn't part with it.

[ericgr]

I once had a fluttering noise that I spent some money on trying to solve. It turns-out it was the fan shroud. The engine will move around on acceleration and a slightly out of adjustment fan shroud will cause a fluttering sound.

I realize the thread has focused on involved solutions to the problem and it may indeed be an involved problem. However, my experience dictates that mechanics miss these kinds of simple answers. If it were me, I'd move the fan shroud a bit (check adjustment) and see if it changes. I'd check my viscous fan clutch, bolts, etc at the same time.

[DanielG]

Thanks, but no, that was not it -- its the axles and bearings

[DavidSoine]

Did you get it fixed?

-ds

[DanielG]

No -- but when it was put back together the noise was gone for a day (they had put some lubrication on the bearings) - so I am pretty sure the last diagnosis was correct. Had this been diagnosed correctly 18 months ago I would most certainly have fixed it and would have enjoyed the car just a little more -- it was already a lot of fun!

Ooh $830 a side. I know not every one is mechanically inclined. But I have found rebuilt axle shaft assembles anywere from $79 to 120 a side. They come with a life time warranty. My 380 actually has the same problem on the left side.

[Kebowers]

Being the unfortunate owner of an sl-600, and previous owner of 380 se(AMG engine) 500 sel and 560 sel (126's), I can assure you repair costs for the MB versions later than the 560sl are an order of magnitude higher.

It's really unusual for the axle shafts to fail in a way that causes the noise you describe. Very unusual for a driveshaft to fail in a manner that makes noise only at a specific speed.

Please note--both the driveshaft and rear axle shafts rotate at a speed directly related to road speed, not engine speed--they do not 'see' the gear at all. If you have a noise that is specific to a GEAR and engine speed--it is not the driveshaft or rear axle.

There HAVE been some instances of reverse clutch disks in the automatic transmission rattling at 1500RPM. There is a TSB on this. It will do this in all shift position except 'R'

Fix is renewing the inner plates of reverse clutch B3 and setting release clearance to minimum value.

I HAVE seen a loose hub attachment to the axle shaft though--and it will cause weird noises.

[DanielG]

Kebowers -- where were you two years ago?

I never thought that the costs of repairing the vehicle to be too much -- and $830 is a lot less than the cost of parts and effort thrown at the car during the 2 years of the problem-- and had I kept the car I would have done that repair. The car also was starting to get a slip in the transmission, had an oil seep that unfortionately dripped oil in such a manner that it burned on the engine and fouled the air inside the car, it needed a modicum of body work, a new soft top, the wheels were starting to peel clear coat ... etc. It was time for someone more enthusiastic to take it over (and I hope that happens).

I think you hit the problem on the head -- the problem should have occurred at all speeds and didn't and that is why no one could find it.

I do believe you that the newer SL's have costs that are much more and that was one reason I did not look for a newer MB (had thought of going to a CLK cab -- very nice cars).

I am still reading posts and consider myself an MB enthusiast. I have some accessories that I will probably offer on ebay next spring (when I clean the garage).

To all of you that have thought about this problem and offered solutions or commiseration - THANKS -- Keep those beautiful SL's of yours running strong!