Proper use of floor jack and jack stands with a 123-chassis 240D: place where, how? - PeachParts Mercedes-Benz Forum

rino · #1 02-26-2007, 06:12 AM

What areas of contact do you use in order to avoid damaging anything in the delicate frame of the car and its components? Do you place any wood as buffer between the lifting devices and the car? Is it wise to use two blocks of hard wood (I already have two sets of 4"-high, secure wooden ramps that I have been using) under the wheels on the side opposite to the one placed on jack stands (with chocks nailed on the blocks of wood to improve stability and safety) in order to keep the car level so that it will be flat on the lifting devices' contact areas and not resting on them precariously at an angle?

Please contribute any useful ideas that come to mind relevant to this topic, and please make it as clear as possible, even at the risk of being redundant (I am using these tools for the first time and, given the potential danger involved in working under a car supported this way, learning how to do it safely is of foremost importance to me...)

TIA,
Rino

Ara T. · #2 02-26-2007, 06:27 AM

I just use the area directly under the holes that you would use the crappy factory jack. I have a rubber pad on my jack but in certain circumstances I will use wood blocks.

I have also placed jackstands under the control arms in the past.

One thing I would not do is jack the car by the differential. Not on an independent suspension car anyways.

R Leo · #3 02-26-2007, 01:17 PM

Quote:

Originally Posted by Ara T.

One thing I would not do is jack the car by the differential. Not on an independent suspension car anyways.

Why? That's where the FSM says to lift.

toomany MBZ · #4 02-26-2007, 06:26 PM

Quote:

Originally Posted by Ara T.

I just use the area directly under the holes that you would use the crappy factory jack. I have a rubber pad on my jack but in certain circumstances I will use wood blocks.

I have also placed jackstands under the control arms in the past.

One thing I would not do is jack the car by the differential. Not on an independent suspension car anyways.

I understand using the factory jack lifts the car up, on one side only, of course, and the indy rear will drop to it's travel limit. Using the diff [as I have done on every vehicle I have owned without any known difficulties] I cannot detect any dissimilarities raising entire rear end. I might be missing something. I also use the engine cross member as well in front. Too cheap to get rubber pads, so I use wood cushions, and keep a length of 4X4 in trunk, so if I have a flat, I don't need to wind jack so far, and gives a bit more surface area on ground.

winmutt · #5 02-26-2007, 07:10 AM

I dont think this is the correct answer by a long shot. There are "hardened" point under the car for jacking etc. If you look on the side of the car there is a u shaped channel that hangs down, towards the front tires it has a reinforced end. Towards the rear tires there is a metal plate that is bolted in to the hard point. Both of these are fairly easy to spot. I wish I had a pic to show. The only problem is jacking and then putting stands. Usually I get a nice 2' section of 2x6 and run it under the rest of that U channel. you can lift the whole side of the car this way. Perhaps someone else can chime in on jacking but thosejack stands belong under the hardened sections. Also when jacking always have something softer than metal inbetween. Always chock your tires and always put the car in gear AND use the parking brake. If the parking brake has not real effect then fix that first.

Jeremy5848 · #6 02-26-2007, 01:11 PM

To raise the car, I use the factory jack in the factory holes. Then I put a jack stand under the frame at the jack hole. I use a small piece of plywood as a cushion between the stand and the frame -- see photo (I enhanced the lighting so you can see the jack hole). Because of the way the jack works, it doesn't get in the way of the stand, and vice-versa. I repeat the operation for each of the four locations on the car that I need to have off the ground.

I have also used a floor jack under the jack hole position but then I can't get a jack stand in there and don't want to risk putting it somewhere else. I don't know how strong the rest of the frame is.

Some day

I'll remember to take a picture of the jack and the jack stand in position together.

dmorrison · #7 02-26-2007, 01:35 PM

Don't make this to complicated. It's not rocket science.

For the front I use the engine cross member just behind the oil pan to jack the car.
I place the jack stands under the frame box just inside of the jack hole provided by Mercedes. Been doing it this way since I have owned Mercedes, 27 years with no problems.
Look at this post, second page. Those are the 6 ton jacks at Harbor Freight.

617 engine, replacing the oil separator check valve in the upper oil pan.

For the rear I use either the subframe mount area or the differential. I usually place the jacks under the subframe mount area.

Ara T. Don't see why you consider the differential sacred. Ive owned the 300TD for 16 years and have jacked it at this point ever since I got my long reach floor jack about 8 years ago. When I rebuilt the rear suspension. The differencial mount was in fine shape. replace it anyway because I was doing a complete rebuild. But it did not seem overstressed. Remember the differencial is mounted with 4 bolts to the subframe. So the force is on the subframe mounts and the differential mount at the same time. Not just the differential mount alone.

Jeremy5848

Please consider getting another set of floor jacks. I had a set like that quite a few years ago and had the lower straps snap when placing the SL on them. For $25 or so you can get a set of 12 ton jacks at Harbor Freight. I know that HF is not necessarily the best but a set that holds 12 tons should be good for a 2 ton car.

Dave

winmutt · #8 02-26-2007, 01:41 PM

Quote:

Originally Posted by dmorrison

For the front I use the engine cross member just behind the oil pan to jack the car.

Sweet I'll start jacking mine that way front and rear (diff in rear).

Quote:

I place the jack stands under the frame box just inside of the jack hole provided by Mercedes. Been doing it this way since I have owned Mercedes, 27 years with no problems.

Thats precisely the area I was talking about.

Rmcfarland · #9 02-26-2007, 01:58 PM

Make sure and be careful around the jack points if they are rusted, like mine though. Safer to use the frame, IMHO.

justinperkins · #10 02-26-2007, 02:13 PM

Quote:

Originally Posted by dmorrison

Jeremy5848

Please consider getting another set of floor jacks. I had a set like that quite a few years ago and had the lower straps snap when placing the SL on them. For $25 or so you can get a set of 12 ton jacks at Harbor Freight. I know that HF is not necessarily the best but a set that holds 12 tons should be good for a 2 ton car.

Dave

x2. I had those same jack stand and have got to say, they are no good. The narrow base combined with the pin-through-hole design made me very nervous when using them.

Jeremy5848 · #11 02-26-2007, 02:30 PM

My set is at least 30 years old and show no hint of a problem -- maybe they build them cheaper now? But I like the kind you guys are suggesting -- the ratchety feature is nice -- so maybe I'll go shopping.

rrgrassi · #12 02-26-2007, 02:37 PM

I use the cross member behind the oil pan as well.

I have never used the diff on any car, unless the FSM allows it. I typically use the control arms if I am just raising one wheel off the ground a bit, being that it has to deal with the sprung and unsprung weight.

I have a pair of old cast iron/steel ratcheting stands. Each one holds 6000 lbs. Get rid of those whimpy pin held ones. Ask my father how it felt when one of those gave way in the 70's.

rino · #13 01-18-2008, 10:45 AM

Quote:

Originally Posted by dmorrison

Don't make this to complicated. It's not rocket science.

For the front I use the engine cross member just behind the oil pan to jack the car.
I place the jack stands under the frame box just inside of the jack hole provided by Mercedes. Been doing it this way since I have owned Mercedes, 27 years with no problems.
Look at this post, second page. Those are the 6 ton jacks at Harbor Freight.

617 engine, replacing the oil separator check valve in the upper oil pan.

For the rear I use either the subframe mount area or the differential. I usually place the jacks under the subframe mount area.

Dave

Hi Dave, I have no idea if you get to read this, but I sure hope so.
It was time that I got a new pair of jacks, so I followed your advice and
yesterday bought the 6-ton jacks from Harbor Freight.
What now puzzles me is that these jacks' minimum height is 15-1/8" and
the subframe mount area on my 240D is only about 10" from the ground.
Using the 6-ton stands would therefore position the car at a pretty steep
incline... and it appears the load placed on the jack stands should be as
vertical as possible to the jacks for safety reasons, as prescribed by the
manual that came with them.

Can you give me some feedback on this one? From your picture from
that post http://www.peachparts.com/shopforum/attachments/diesel-discussion/25842d1114794674-617-engine-replacing-oil-separator-check-valve-upper-oil-pan-oil-seperator-fix-6.jpg
it looks like you used an even greater height than 15-1/8", assuming that,
as you said, those are the same 6-ton jacks from Harbor Freight that I have...

(With the 2-1/4 ton Craftsman jacks from Sears that I've been using
so far, I've always placed solid wood under the tires on the opposite
end, so as to lift the car about 3-4" from the ground, and then the jacks
under the subframe, with the car's subframe evenly lifted that
way (back and front ends of the car evenly lifted) at about 13.5" from
the ground. That ensured that the load was completely perpendicular to
the jacks, as I understand that to be an important requirement.)

Also, from your picture I can see you did not place anything between
the vehicle subframe and the posts saddles (I was told to always use
something soft in between, such as a short length of 2x4, so as to
avoid possible slippage). What's the right way to do it, metal to metal
or with something soft in between? A clarification here would be
appreciated.

The big question for me however is, is it safe to work under a car
positioned at such an incline?? (I'll be placing the jack stands under
the subframe box, near the jack holes provided by Mercedes.)
Or should I return the 6-ton jacks and get smaller 3-ton ones with
a lower minimum height?

TIA,
Rino

dmorrison · #14 01-18-2008, 02:13 PM

Rino

A couple of opinions. I have always placed the jack under the frame box on the W123 and W107. I have not used a 2X4 or any other "pad" between the jack and frame, the wood can split and cause the car to shift. A hard rubber pad would be better. Harbor freight makes them for the 6 ton jack. http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95952
I have not bought them because I am comfortable with what I am doing, And I will spend money at Harbor Freight ( can't get out of that store without dropping $100 ) Make sure the frame box is centered over the jacks stand pad. I make contact on both sides of the pad at the 2 edges of the boxframe. I jack the car up raise the jack to just below the boxframe and slide it towards the rear allowing it to make contact with the boxframe at the two pad spots. Do the same think on the other side but make sure the 2nd jackstand is raised the same amount of clicks as the other one. This way your car should be level ( left to right ). Lower the car on the jackstands and give it a shake so you can see it's stability on the stands. If it does not seem stable , move the jackstands to get it more stable.

I do make sure that the transmission parking pawl has engaged when I stop the car, engage the parking brake and I park on a flat, hard surface.
the car will sit at a angle on the jackstands. The amount shown in the picture allows me to work under the car easily but I am not uncomfortable with the angle the car is sitting at. I am just working on the engine. If I have to work under the complete car I use 6 ton jacks ( I edited this to change the size to 6 ton jacks )and jack the car up pretty high in 2 stages. I also have the HF long body jack that can raise the car 33 inches. As I said I do this in 2 stages.

If your uncomfortable with just the 2 jacks. I sometimes leave the raising jack under the engine crossframe instead of removing it after jacking. Drop the car down on the jack stands and allow the raising jack to just kiss the frame. Now your supporting the car in 3 places. Or place another 2 jacks near the 2 installed but just barely touching the frame, a sort of backup.

Always make sure you chock your front wheels when jacking just the rear of the car. Good chocks, not 2X4's.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96479
It will roll on you when jacking and be unstable when on the jack stands.

Good luck and be careful.

Dave

winmutt · #15 02-26-2007, 03:31 PM

FWIW I always leave the jack jacked up just shy of the bottom of the car near where ever I am working. Even jacktands wobble....