I've spent the last few hours reading threads on tranny slippage and flaring, and am more confused than when I began.

Bought a 280CE a few weeks ago with 170K miles. Among the checks I made was notice that the tranny and diff had been serviced at 162K. Seemed to shift ok. Checking the tranny level cold showed it to be several inches above the full mark, but at the time I didn't know this was odd. The link arm across the top of the engine had a loose set screw, and after shortening the arm's adjustment, not only did I get firm shifting, but was getting tire squeal on both the 2-3 and 3-4 upshift along with a head snapping shift. Backed off on the link arm adjustment, and the snap and tire squeal lessened to the typical Mercedes firm "shift lurch".

Friday AM, when accelerating from a stop, the tranny slipped on the 2-3 shift; the engine RPMs (sound, as this car has no tach) rose and for a second the car moved slowly until it felt to lock into 3rd. Didn't happen again in 150 more miles of driving on Sat., and as I was having overheating problems too, I spent Sunday and Monday PM replacing the radiator. (The cracked plastic upper hose fitting simply wasn't fixable.)

All that was open after I got the radiator in was the local gas station and I bought antifreeze and a GUNK product, if I remember right named TransTune as they had no ATF on the shelf.

Drove the car 2 miles before adding the Gunk just to see if the rad connections were tight, and the tranny slipped badly. Added 3/4 of the quart of additive to the tranny while engine hot but not running, measured to the full mark and did a test drive. Seemed to shift ok.

Next morning going to work, slippage was significant both on the 2-3 and 3-4 upshifts. Got home and checked fluid level...low. ???Added the rest of the quart of Gunk stuff and it came up to the full level.

Still slipping this AM, and after a quote for a rebuilt tranny higher than I paid for the car, plus a suggestion that the additive might be the problem, I pulled into Jiffy Lube to have them flush the tranny. The first thing they did was pull the stick to find the ATF level so low it wasn't even hitting the bottom of the stick. They put in 3/4 quart of ATF, put it in gear several times with the brake on (I guess this was to get fluid circulating well) and I left without doing the flush. Driving the few blocks back to work showed no improvement. I pulled into the parking lot, turned off the car and checked the stick again. It was slightly above full. Re-set the link arm again to see if the firm shift snap of before could be returned and overcome the slip. Nope, all I succeeded in doing was confuse the car more. It still slipped, but the RPMs told the car to shift again. I'm guessing on this last, but I got the sense that on the 2-3 upshift when the RPMs rose while the slipping was going on, the tranny then did the 3-4 shift, slipped some and then locked into 4th.

Back in the parking lot, I returned the link arm to the longer position, and checked the fluid level again with the engine off. It was back to the way overfull level I had when I first looked weeks ago.

The search thread hasn't given me a clear answer.

1. I was encouraged that there is talk of some vacuum adjustment that can fix this slip/flare problem, but was that just on diesels? Help?

2. Why am I overfull when cold and the level is supposed to check low, and apparantly at the right level when hot???

3. Why has it registered full sometimes and still needed two top offs in two days

4. Have I screwed up by putting in the additive and done something like slicked up the clutch face plates???

5. Remember, I "think" the tranny was serviced only 8K miles ago. There are no leaks or drips evident and no burned smell. What the heck is going on? Wouldn't slippage appear more gradually if it is just a tired transmission?

6. If there is no solution other than a tranny re-build, which I can't afford, and since I need to drive the car daily, am I doing more harm, or is there some other additive designed to address slippage that is worth using?

I had a similar situation on the '72 107 chassis SL when I bought it. In a test drive with a local AT shop owner, he noted that the slipping was BETWEEN gears (i.e., during shifting), and that there was no slipping once the trans was in a gear (1st, 2nd, or 3rd). That, he said, was a good sign as slipping while in a gear would be an expensive bands/clutch problem.

He said replacement of the external modulator should correct the between gears slipping, so I bought a new one (about $40) but never got around to installing it so I can't vouch for the efficacy of that repair. Worth considering, though.

That is the crux of my problem Doc. Thanks for the tip. Driving home tonight in stop and go traffic where acceleration was very gentle, the shifting was smooth and frankly better than before with no lock up thunk. It downshifted properly too. But at the exit ramp when speed up need was more "normal" the slippage between gears as you describe it is really disconcerting as you can't accelerate much for a couple of seconds until lock up completes.

Still looking for additive advice since I continue to wonder if the Gunk product I used is a part of the problem. Its called TransFusion and the bottle says it conditions and loosens sluggish transmissions and mine sure is loose now.

First, you need to get the tranny fluid leak fixed -- as long as the fluid is low, the tranny will slip and shift slowly since compressed air and oil foam doesn't act like pure hydraulic oil in the clutches. You will eventually also ruin the tranny from the slip.

After you get the leak fixed, you will need to re-adjust the linkage for proper shift timing and feel. You didn't list the year, so I don't know if you have a modulator or not.

Check the tranny cooler lines for leaks -- the one on my 220D wore through because the rubber in one of the clips wore out, and it only leaked while the engine was producing power -- that is, only while accelerating. At rest, the line sat on the hole and nothing came out! No drips in the drive, nothing, but it must have been pouring out while I drove!

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!

I agree with the modulator and also suggest checking the plastic vacuum line and the rubber tubing connector going to it.

Someone else had posted that they simply replaced the rubber tube and it drove like it was new. On a car that old, with all the heat etc. they get brittle and hard. I would simply replace it. Easy to do. Watch taking it off the vacuum modulator as they can "bond"on. Also the plastic on the modulator may be brittle as well.

AND yes, ATF!

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Thanks guys. I don't have a leak that I know of. I think the problem was pilot error in reading the dipstick as I thought so long as the engine was warm the reading would be right...checking it with the engine running and after the top off yesterday and it is now consistently about 1/4 inch above the full mark. (by the way, talking directly to the MB tech back in Florida that blessed the car before I flew down and got it, reveals that despite forum comments about the tranny dipstick reading low when the car is off and cold; a very high fluid level is correct.) The car is a 79 by the way and I sure hope there's a vacuum modulator & hose as this sounds like the key. The crappy Chilton's manual gives no clue, but from reading posts, I get the sense if it exists, it is on the right side of the tranny just above and in front of the pan right? And that the hose is/was originally metal? If I don't see any broken or loose hose, is there a way to check the modulator's function? And if there IS a loose connection, is there a method to "tuning" the modulator (I get the impression it has some external adjustment knob), or is it trial and error?

While under the car tonight, I'll also double check the radiator fittings as I suppose it is possible the junk yard radiator isn't circulating the ATF properly.

It is of some comfort that since the slippage started all at once and not gradual, and that it is only during the shift, that the problem could be minor...I have my fingers crossed.

You have a 722.x tranny with a modulator.

You will need to find the vac line to the modulator and check the rubber connector on both ends. Get a MitiVac hand pump if you don't have one and check to see that the modulator and line hold pressure, and what sorr of vac you have on the manifold or control valve (don't remember at the moment if this is a gas or diesel engine).

Once you have established vac integrity and proper vac signal, you can start with the adjustments. See some other posts on this subject, Steve Brotherton has a very nice page (or refers to one, anyway) describing the various adjustments. The link does a much better job than I can of describing what to do.

I suspect an adjustment problem rather than something serious.

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!

Crawling under the car last night, the vacuum line from the manifold to the modulator is metal except for the last four inches. Except where I cannot reach or see it as the line passes behind the engine, it appears intact and in speaking with an MB tech on the phone last night, the 4 inches of rubber hose indicates to him that some work was previously done since he says the entire line was originally metal. The grease and crud over the modulator tells me it hasn't been fiddled with in many years if ever, but rubber hose appears tight and still flexible. Since I'd also pulled the lines from the bottom of the radiator installed two days before to make sure there was no blockage, and blew ATF all over the garage floor and myself when I turned on the engine, and had cleaned up, refilled the tranny and the car was off the ramp, I'm to call him back tonight.

Absent a vacuum tester, we are going to presume vacuum and he will walk me thru a test of the modulator after I get the car back up on the stands tonight.

I'll take your advice and seek the posts you mention too.