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  #1  
Old 11-04-2002, 12:45 PM
Four.Five
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1972 4.5 rear compensator question?

I am a new (9 days now) MB owner and would like to thank everyone on this board for all the information that I've used to work on my new car.

Now for the question... my 1972 280se 4.5 sags in the rear and the tires are tipped in at the top. Will a new hydro unit fix this problem, or is there more going on? I've found 2 answers, yes and no.

Any input is appreciated.

thanks,

Steve (four.five)

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  #2  
Old 11-04-2002, 09:00 PM
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Location: Evansville, Indiana
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A dead compensator will make the rear either jack up terribly or more usually droop. Get rid of it and replace it with the compesator spring. Much cheaper, won't self-level, but I've heard the compensator only lasts a year or two under normal use -- last price I saw was $1700 wholesale......

However, if the car hasn't been driven for a long time, the compesator can droop until you bounce the rear wheels enough to pump it back up (it's pnuemato-hydraulic). Make sure the lever is still connected to the body so that it is operating, too, before condeming it.

Sagged rear springs can also make the back end ride low, too.

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #3  
Old 11-04-2002, 09:24 PM
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Location: So Cal, Beach
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Steve

The answer is Yes, a new hydro unit will fix it, and it is the only way to go. The other fix is "The Spring", this cheeseball fix is poor at best.

The down side is the price of a new unit, $750.00 last time I checked.

I had the same problem about 5 years ago, and purchased a brand new USED compensator from my local "Treasure Chest" for about $235.00, and it is as easy to install.

My 108 rides high on it's springs and still kicks butt with the original shocks, the only thing I have had to replace is this unit, after 117,000 miles and 30 years, do you think I should contact MB and complain about this?

If you can't find a good used one in your area, let me know.

Good luck.
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300CE
280SE 4.5
Sandals (size 11)
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  #4  
Old 11-04-2002, 09:40 PM
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Hey Peter, how's it going?

Good point, about the lever, as we don't know the condition of Four.Fives ride.

Steve, check these things out first, and let us know all the stats on your 4.5.
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300CE
280SE 4.5
Sandals (size 11)
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  #5  
Old 11-05-2002, 01:02 AM
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Had the same problem with the same car. Put in new compensator. It has worked fine for 6 years so far. I had another 4.5 with the spring that worked OK too, if cost is a big issue.
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  #6  
Old 11-05-2002, 07:24 PM
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Hey Tim!

I've been driving my 280 to work this week. Got a nice surprise on the way home when the dash lights came on (yeah!) -- until I foolishly tried the rheostat. Out again, but hoping they "pop" back on. Will check the fuse later, too.

My 280 has the spring -- compensator was an option, I think. My indie mechanic has been working on these cars since new, still maintains you are best getting rid of them, but hey, suit yourself! It would be nice to have self-leveling, as those swing axles do make the car drive strange if they are very far off of level.

My shocks have been replaced with something like Monroe's -- blue paint -- definitely NOT Bilteins or anything remotely OEM. Handles just fine, but you can feel even grains of sand....

Crappy tires don't help, either. Shake like crazy about 70 mph.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #7  
Old 11-05-2002, 08:10 PM
Four.Five
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I checked the back end, and it appears the compensator is still attached to the body if you mean the "J" shaped lever that is attached to the rearend with 2 large allen bolts and appears to be holding the comp in place?. Still waiting to buy a manual.

Still trying to sort out why it runs very rough until she warms up 160+, then runs fairly smooth. Anyone live in the greater seattle area that would be willing to give there educated 2 cents sometime?

Steve
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  #8  
Old 11-05-2002, 08:57 PM
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Steve:

The EFI is on start mixture until 150F -- if it runs rough, it is probably too rich, but this can be from a number of reasons. Mine does the same thing, surges, too, until hot.

The leading cause is probably a loose or bad air temp sensor -- it's in the air cleaner intake. Make sure the wires are intact and that the connector is actually plugged in and that the wires connect -- not unplugging this and removing the air cleaner housing seems to be common. If this is shorted or not connected, the car will sometimes run VERY rich, to the point you can smell it and see black smoke.

Other problems can be the coolant temp sensor (in the intake manifold) and a bad MAP sensor (on the firewall). Last is a bit expensive.

Could just have been set for max performance, too -- rather wide specs for this beast. Pre emission controls days.

Best bet is to find someone willing to play around a bit with a CO meter, and attempt to set the CO correctly.

I have possision of a factory training manaul, so can get you specs for temp sensors and etc if you need them.

For the compensator, the leveling is probably internal -- the air suspension may be the one with a link to the body to sense height.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #9  
Old 11-06-2002, 12:13 AM
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Quote:
Originally posted by psfred
I've been driving my 280 to work this week. Got a nice surprise on the way home when the dash lights came on (yeah!) -- until I foolishly tried the rheostat. Out again, but hoping they "pop" back on. Will check the fuse later, too.
Peter
Just so you know Peter (I know it's off topic), but you should pop the dash unit out and take the rheostat off (only 2 screws) and clean it/tighten it up. I did with mine and it works like a charm now
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  #10  
Old 11-06-2002, 07:48 PM
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Tom:

Ah, so I would if I could figure out how you get the bloody thing out!!!!!!!!

Not like the 220D, that one just pulls. This one has a knob somewere holding it in that I cannot even see, let alone remove!

Any hints, this is driving me nuts!

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #11  
Old 11-06-2002, 11:11 PM
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Location: near Scranton, PA
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Go in from underneath, there is 1 thumb-screw type thing that you take off (IIRC) and it will pull right out. You may want to disconnect the speedo cable for more clearance. I don't remember if there is a nut holding it on or if I'm thinking of another car.... but I'm pretty sure there is.
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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k
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  #12  
Old 11-07-2002, 05:49 PM
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Join Date: Jul 2001
Location: Atlanta
Posts: 194
psfred,
Its called the "knurled nut". I had to remove the emergency brake bracket on my 109 car to even get to it. Not all 108/109 cars have them or if they did originally they have been removed.
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  #13  
Old 11-07-2002, 07:20 PM
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Location: Evansville, Indiana
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Thanks Clunker!

As I said, I looked up and can't even find the cluster, let alone the nut from underneath. I could touch the "bridge" from the radio speaker hole, but no way my hand would get far enough in THAT spot to get to the nut.

I've heard this is a SERIOUS PITA -- plan on cuts and scratches. Big bother. For those of you not familiar with the W108, the dash is deep, the steeing column has two "columns" (one for the steering and the other for the shifter -- column shift, alas), and the cluster is WAY up there -- at least a foot and a half. Off center, too, just like the wheel and engine. Strange car. Lots of ductwork and brackets between the cluster and the bottom of the dash.

Have to do it soon, though -- the odometer doesn't work, either, and I have this plan to get 250,000k badges for all my Benzes....!

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #14  
Old 11-07-2002, 11:49 PM
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Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
Clunker:

Not too bad after I took the parking brake down -- not easy, but not too bad.

I now have dash lights and the odo works, too. Dropped a dash lamp, though (the one for the right side of the speedo), so can't button up until I get a replacement tomorrow.

Kinda cool to have the heater levers light up, too!

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #15  
Old 12-09-2002, 03:32 PM
Four.Five
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280se 4.5 Compensator install???

I found a new used comp, and the cd manual says to make sure there is "no load" on axle tubes. question I have is does that mean hanging free or jack stands under tubes? I'm sure that it would be obvious if I was actually doing the r&r, but I'm trying to plan for tools etc. With regard to install, it also says to place comp in "clamping device", is this the same as a spring compressor and is it necessary? And what is the trick in removing the high pressure steering hose? it's a bit tight back there!!

thanks in advance.

steve (four.five)

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