jack stands / ongoing noise

[hands_aus]

I bought 4 new 2000kg jack stands recently.

My questions,
Can I raise each corner independently and insert a stand
or do I have to raise the front (jack under sump) or rear (jack under axle) of the car and insert the stands then lower the jack.

How stable should the car be while up on stands?

I want to take off the front wheels and get in there and look for my continuing rattle.
This noise has been there for about 3 years and has survived the rear axle and drive shaft rebuild and the front brake rebuild with new shock absorbers and new subframe mounts.
I have also shimmed the thrust bush with the noise persisting.

This noise is movement related and never appears while the car is stationary.

Recently while driving the car down a long steep hill (no other cars around on a quiet Saturday afternoon) I put the auto trans into neutral and turned the engine off.
The noise persisted even though I touched the brakes.

I have come to the conclusion that the noise can't be motor or oil pump related.
Would running the auto trans in neutral like that disengage the trans?
Can I eliminate the transmission from my thinking?
Could it be suspension or steering related?
The front wheel bearings had additional grease added to them in April. There didn't seem to be anything loose in there.

The noise does not appear if the front wheels are spun while off the ground. I did this when I did the grease and oil change in April.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Shvegel]

Is the noise speed related? In other words does frequency of the rattle increase as the car goes faster or is it something bump related?

[bpossel]

Hi Bob,

If your subframe mounts are in good condition, then you should be able to put each jack under the following locations based on the attached picture (from an earlier post, not my car...).  When I place my jack stands per the attached picture, I jack up the front (one side at a time) placing the lift under each arm, under the spring location.  For the rear, jack up each side also under the spring area and place jack stand location per attached picture.  Using good quality jack stands, your car should be stable and safe.
- Motor mounts loose, bad?
- Exhaust hitting the underside firewall area?
- Bad king pin?
- Subframe mount loose?
- Exhaust heat shield loose?

Download Attachment: jack stand points.jpg
74.89 KB

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[graphic66]

My mystery rattle was the bottom support on my radiator expansion tank. It had come unsoldered and was an easier fix than find. Your 250 probably has the round tank though, my 230 has the flat tank, so that may not be it.

[George Davis]

Hi Bob,

Noises like that are most annoying.  Can you describe it?  Does it change as your speed changes?

As for jacking, I usually jack up one end of the car at a time.  Front under the subframe, and rear under the diff.  Jack stands can be placed under the rear axle as well as the locations Bob P. shows.

I'm not sure you can eliminate the transmission entirely.  According to the BBB those transmissions have a rear pump which pumps when the driveshaft is turning, as it would when coasting.  This design allows an auto trans car to be push-started, unlike designs that have only a crank-driven pump (which your trans also has).

George Davis
'69 280 SL Euro manual

[hands_aus]

Hey Bob P
Thanks for the pic.
new subframe mounts in November 06,
new motor mounts in 2004
no exhaust heat shields
king pins are ok and well greased
I will check the exhaust fitting when I get the car up on the jack stands.

Hey Shvegel,
The noise is intermittent at low speed but increases as speed increases.
It sounds like two flat washers touching or jiggling on a spinning shaft.

Hey graphic66
yep football type expansion tank.

Hey George
The auto trans filter and fluid haven't been replaced since June 1999 at 155339 miles. Since then the car has done 12868 miles, most of which I have done since June 2002 when I bought the car.

Maybe I should check the tightness of the filter and replace the fluid as a precautionary measure.

Earlier I shimmed the tacho thrust bush thinking that the noise came from there.
By the time I find this noise I will have rebuilt the entire car.

Thanks for all your responses

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[hands_aus]

quote:Originally posted by hands_aus

It sounds like two flat washers touching or jiggling on a spinning shaft.

Hey again,
I thought I would bring this topic up to date.

December 2006 I won a $250.00 service voucher from the local MB dealer.
Today they did a grease and oil change using my oil.

I also asked them to inspect the car looking for 'THE NOISE'.
A mechanic and I took it for a test drive. He decided to put it on a hoist and run it while suspended.

He found a loose dust excluder type steel washer on the front section of the drive shaft. See picture

Download Attachment: DriveShaft text.jpg
28.04 KB

It is located next to the rubber center bearing mount. The hole of the washer is not a close fit to the shaft. When I felt it i could feel a curved inner edge (shaft side). I think this curved edge goes into the rubber bearing mount.

The picture is not mine but it does show the location.

The picture is exactly like what I see, but when I put my hand up there I can feel this metal washer moving around.

The washer can be rotated and wobbled by hand, however there is not a lot of play.

I checked the EPC for a part number but there is no reference/picture of this washer.

Does anyone know of this washer?
Is it a ring-in?
Maybe a left over from an earlier job?

The car is 40yo, so anything is possible.

Thanks

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[mbzse]

quote:Originally posted by hands_aus

quote:Originally posted by hands_aus

It sounds like two flat washers touching or jiggling on a spinning shaft.

../..He found a loose dust excluder type steel washer on the front section of the drive shaft. It is located next to the rubber center bearing mount. The hole of the washer is not a close fit to the shaft. The washer can be rotated and wobbled by hand, however there is not a lot of play. I checked the EPC for a part number but there is no reference/picture of this washer.

Does anyone know of this washer?

This is an original part, it is a throwout protection cover, shaped like a cup, for the intermediate driveshaft bearing. However, the design came in late 1966 and was changed late 1967, so not very many cars have this design, and it is not illustrated in the english versions of the workshop manuals. Unfortunately the parts list is quite neboulous as well.
Anyway, the protection cup cover is locked in position onto the short, splined shaft (with the inner bearing race) by the large diameter snap ring. In your case, the snap ring may have come off. Dis-assemble and have a look!

/Hans in Sweden

[hands_aus]

Hey Hans,
My car is a 67 model, seems to be the right period.
Could you provide a part number and maybe a pic for that protection cover?

Thanks for the reply.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[ted280sl]

Bob,
  I just read your post and I believe you got some good information regarding where to place jack stands. I would love to purchase a garage lift for my house but, I do not believe my spouse would consider it a good investment. I was concerned that no one raised an issue with placing a jack under the oil sump. I do not believe it is reinforced and I would expect that would cause quite a bit of damage. I usually place my jack under the front subframe to raise the car and place jack stands where the picture indicates on the front of the frame under the passenger compartment. To raise the rear of the car I usually place my jack under the rear end. I then place my jackstands where the shocks are connected to the rear axle.
  Too many people have died under cars because they were not careful. It is obviously very dangerous to have a car fall on you. Buy good quality jack stands and be careful. I hate to preach but, I would hate even more to hear of someone getting hurt.
Regards,
Ted 1969 280SL

[hands_aus]

quote:Originally posted by ted280sl

Bob,
  I just read your post and I believe you got some good information regarding where to place jack stands. I would love to purchase a garage lift for my house but, I do not believe my spouse would consider it a good investment. I was concerned that no one raised an issue with placing a jack under the oil sump. I do not believe it is reinforced and I would expect that would cause quite a bit of damage. I usually place my jack under the front subframe to raise the car and place jack stands where the picture indicates on the front of the frame under the passenger compartment. To raise the rear of the car I usually place my jack under the rear end. I then place my jackstands where the shocks are connected to the rear axle.
  Too many people have died under cars because they were not careful. It is obviously very dangerous to have a car fall on you. Buy good quality jack stands and be careful. I hate to preach but, I would hate even more to hear of someone getting hurt.
Regards,
Ted 1969 280SL

Hey Ted,
Thanks for the advice.
I have not used the sump. I think I made a typo.

Today I spoke to the mechanic who did the axle and drive shaft rebuild.

He suggested 2 or 3 ways of curing the problem noise.
As the cover is not on the 280sl he said why not remove it from my 250sl.
Alternately he could 'locktite' it to the drive shaft and if that didn't work then maybe remove it and pein the inside and then push it on the shaft.

At this time I don't intend to make it a major job, so I suggested that I could try wrapping some tape around the rubber housing and the metal cover.
He thought it was worth a try.

I will find time on Saturday to see how this works and will provide feedback here soon.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Longtooth]

Bob, I hadn't seen this series of messages on jacking up the car and jack stand locations before I needed to remove my wheels to get them painted (and replace tires finally after 24 years but only ~25k miles), so I looked in the Service Manual to see if there was anything in it for jacking up the car and supporting it.... or more importantly to me, any caveats.


The Service manual addresses this in the very first job in the manual.... right in the front of the manual directly after the "General Technical Data"..., Job No. 0-6.  

Front: Jack up at Front Axel Support.  "Place Jack stands at left and right under the chassis base panel near the lateral support tubes for the jack of the car.".. i.e. near the tubes for the car's jack.  ... similar to pic's provided by bpossel's post.

Rear: Jack up "at center of rear axel housing."  Place stands at the left and right under the chassis base panel near the lateral support tubes...." [same as for front jack stands location, but rear lateral supports].

I've watched a restorer's approach on the W113's also... he places the rear stands under the rear axel supports.  Basically, it's all pretty much the same method I use for my '65 Chevy Pick-up.  My jack stands don't have a flat top, so I place a short piece of soft 2x4 wood block between stands and car.... also between jack base and car when jacking up.  Rdwood scrap 2x6's are plentiful around my house and it's soft so wood compresses before anything on the car can.  

BUT, I strongly recommend whenever you use jack stands you also place something else under the car that will keep lowest point at least 10" off the ground just in case one of the stands fails or is off-balance or the car get's hit by something else --- most especially if you have to stick a limb or head under it, even for a moment --- in CA I have to always assume an earthquake will occur at any magnitude at any time.  Normally I use the tires (on their wheels) under the car for insurance, except in the last case where I was taking my wheels and tires in to have wheels repainted and tires replaced.  This time I used a couple of left-over beams (6x8's) stacked on each other (11" total height) ... a pair crossing under the differential and another pair under the front axel supports.  

I do the precautionary routine religiously as I met a guy that didn't.... not something I want to have reduce the rest of my life to a serious limitation on physical motion --- he was in a wheel chair having lost mobility from waist down!  For want of a few more minutes in prep, he lost the irreplacable.  It only has to happen once.

Longtooth
67 250SL US #113-043-10-002163
'02 SL500 Sport