I changed my oil for the first time on my recently purchased 91 300E MB 4Matic. I jacked it up with the MB pole type jack put a Jack Stand under the rubber bumper and then did the other side.

To make a long story short the car fell and not exactly on the bumps where the jack stand were. The jack was dis-abled also. I used another standard jack on the frame to lift the car and put things in place.

In order to be safe and potentialy save your life, don't go under the car using just the jack, use Jack Stands. If you jack up both sides it appears the jack is not safe. I highly recommend putting the full load of the car on the Jack Stands and REMOVE the JACK. Rock the car with your body to be sure the Jack Stands are stable.

I know this is common sense, but I believe the problem occured because I left the Jack in place and I am a newbie to MB pole jacks.

I don't use the MB jack, but as a rule of practice, I do not use jack stands to back up the jack - I do the reverse. I.e. I lower the vehicle onto the stands and verify it is secure, then use the floor jack positioned to backup a failed stand wherever I might be under the vehicle.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

That is kinda of what I did, but by leaving the MB Pole stand on one side it caused a problem. I would normaly on other cars with other types of jacks use the jack and then put a jack stand in place in case the jack failed.

I have had MB jacks tip over (not on me) twice in my lifetime. I always use a chock now, if I have to use the MB jack. I found cool little MB folding metal chocks on eBay, for very little money, and have added those to my cars' toolkits.

I was not under the car at the time! Sorry if I was unclear before I edited my post. I'd never get under a car on a jack.

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David
1986 300E Anthracite + ECodes + MB Mileage Award

Yikes!

For $50-60, you can get a full-sized low end floor jack and a pair of stands.

So much more convenient, and a cheap life insurance policy.

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1986 300E 5-Speed 240k mi.

I use a Mercedes jack to lift the car and then lower it on a jack stand. I've been thinking about getting a floor jack but I can't figure something out...if I use the floor jack to lift the car using the rubber bumper, where do you put the jack stand.

As for the jack failure, I wonder if one side of the car is on a jack stand and you try to lift the other side with the M-B jack, would it exceed the weight the jack can handle?

BTW, whenever I jack up the car I apply the parking brake and also put chocks in front and back of the off corner wheel.

I think the safest way to get under a car is to put it on ramps. Next safest would be on jackstands with the wheels chocked.

I once saw something on TV where a dead man was shown under a car that had fallen off a bumper jack. It wasn't a pretty sight.

Look just about 5 inches to the inside of the rubber bumps, you will see the frame. I believe that would be a good spot for a jack or jack stands.

Right. Big floor jack lifts entire front end of a car at once under the center crossmember. This is both faster and safer than lifting one side at a time. No messing around.

Don't care for ramps myself most of the time. Besides, they do you no good if a wheel has to come off.

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1986 300E 5-Speed 240k mi.

I use blocks of lumber, backed-up with jack stands and a floor jack.

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1998 SL500 Sport Model

Never ever rely on a jack to hold up a car while working on the car, with the limited exception of an emergency roadside tire change. Always use jack stands and wheel chocks when working on the car. I would disagree with the use of wood blocks, with unknown weight bearing capacity, being used in lieu of properly positioned and rated jackstands. Best visual reminder is to get a tomato sauce can and drop it on a bug, then remember, you'll be the bug.

I was only thinking of ramps if you were going under the car.

It's awful hard to yell for help with 2+ tons of steel resting on your chest.