Transmission flaring from a stop? - PeachParts Mercedes-Benz Forum

Strand · #1 08-30-2014, 08:52 AM

Hi all,

On my current trip to New Hampshire, I begun observing some transmission behavior that's given me some cause for concern. I've searched around the forums to the best of my ability, but can't find something that matches my problem.

The 300D has begun revving up from a dead stop. She crawls forward for a second or two under higher RPM until the gear "catches", then we're on our way as per usual. In particularly bad instances, this hesitation comes with a brief shudder as the car finds the gear.

To me, it seems like the car is partially losing forward gear every time I come to a complete stop. It still idles forward, but doesn't seem to be entirely "in gear" under initial acceleration. However, the rest of the gears work fine (up shift, downshift, kickdown, reverse).

Any ideas? Any help would be much appreciated.

upshift · #2 08-30-2014, 09:10 AM

How's the fluid level? Does the fluid smell burnt or have a lot of metal/clutch in it?

The symptoms you describe could simply be low trans fluid.

leathermang · #3 08-30-2014, 09:23 AM

When was the trans fluid and filter changed last ?

Strand · #4 08-30-2014, 09:56 AM

Trans fluid and filter were changed under the PO last year apparently, and the car want driven much. Both of the mechanics who took a look at it claimed it looked "fine", but all of this could mean anything. I'll see if I can stop by the Mercedes dealer in Boston later today to get it serviced ($$$, but I don't have a fresh filter or gasket on hand).

patbob · #5 08-30-2014, 12:39 PM

When the first gear clutch wore out on my transmission, the car wouldn't creep forward at idle, and the engine would rev and rev and the car wouldn't hardly go forward at all, until once it was moving enough to switch to second (then it'd operate fine with the rest of the gears). Yours doesn't sound like that, so the clutch probably isn't worn out. I'd check the fluid level before taking it to the dealer.

Better than taking it to the dealer, who never works on these 30 year old cars anymore, I'd check the mechanics list and see if there's one knowledgeable about these old cars nearby to take it to. Perhaps give them a call and see if they know which transmission shop in town knows the transmissions best (that's how I found the tranny shop to rebuild mine).

Junkman · #6 08-30-2014, 03:59 PM

What happens when you manually shift it?

I had multiple issues that were straightened out by flu
I'd change, governor adjustment, vacuum repair & vcv adjustment. There are trans manuals around that help.

Strand · #7 08-30-2014, 05:24 PM

Quick update: I'm unfortunately not going to be able to work on the transmission symptoms for a few more days, as the fuel pump decided to give up this morning (crank, no start--no fuel seems to be reaching the engine). Oh well.

Conveniently, it's Labor Day weekend, so the 300D will be enjoying an extended stay in central New Hampshire.

leathermang · #8 08-30-2014, 05:29 PM

Quote:

Originally Posted by Strand

Quick update: I'm unfortunately not going to be able to work on the transmission symptoms for a few more days, as the fuel pump decided to give up this morning (crank, no start--no fuel seems to be reaching the engine). Oh well.

Conveniently, it's Labor Day weekend, so the 300D will be enjoying an extended stay in central New Hampshire.

Don't jump to ' fuel pump' first...
other things to check ...and cheaper to fix first...

Strand · #9 08-30-2014, 05:34 PM

Quote:

Originally Posted by leathermang

Don't jump to ' fuel pump' first...
other things to check ...and cheaper to fix first...

What would that be? The fuel filters have both been recently changed, most recently the primary only last week. Everything seems primed and ready to go, engine is cranking but behaving like absolutely no fuel is getting to it (no sputter, no rough start). I'm at a bit of a loss.

Diesel911 · #10 08-31-2014, 01:14 AM

Quote:

Originally Posted by Strand

What would that be? The fuel filters have both been recently changed, most recently the primary only last week. Everything seems primed and ready to go, engine is cranking but behaving like absolutely no fuel is getting to it (no sputter, no rough start). I'm at a bit of a loss.

If the Fuel in the Tank has gotten contaminated by a load of bad Fuel. I have seen a new Fuel Filter last 30 Minutes after it was changed before it plugged and stopped the Engine. Filters don't care about when they are changed last they just do their job and get plugged when they stop enough contaminants to plug them.

Then there is also the Fuel Tank Screen that can get plugged. If you have a ½ Tank of Fuel you can swap the Positions of the Cigar Hose and the Fuel Inlet Hose where they come off of the Fender well and that bypasses the Fuel Tank Screen and draws Fuel from a higher position in the Tank (note that drawing Fuel from a higher position in the Tank also means you are going to run out of Fuel before your Gage reaches Empty). If it runs good with the Hose positions swapped your Tank Screen is plugged.
You can change the Spin-on Filter with a new one and put the old one in a Zip-Lock Bag. If the new Filter does not fix the Problem save the one you removed for re-use later.

I had the same Transmission symptoms and I changed the AT Filter and Fluid and the Symptoms went away for not quite a year when My B2 Piston Broke.
I am guessing that when I had the original issue that the B2 Piston was sticking and changing the Fluid and Filter got enough pressure to it for it to work for awhile.

But there is no way to tell if that is what is your issue without removing the B2 Piston and at that point you might as well replace it due to the labor involved.

There is a Lip Seal in there that can get hard and there is an Aluminum Bushing that is replaced with a less grabby Nylon one.
Of course as others have stated there is other things that can cause a problem then the B2.

At the bottom of the Pic the arrow points to where the B2 Piston looks like it was binding on the Aluminum Bushing. The Aluminum Bushing is not shown in the Pic.

Strand · #11 08-31-2014, 10:23 PM

Quote:

Originally Posted by Diesel911

If the Fuel in the Tank has gotten contaminated by a load of bad Fuel. I have seen a new Fuel Filter last 30 Minutes after it was changed before it plugged and stopped the Engine. Filters don't care about when they are changed last they just do their job and get plugged when they stop enough contaminants to plug them.

Thanks. I hadn't considered the possibility of bad fuel, but the problem did occur after a relatively recent fill-up in Connecticut. Would a batch of poor fuel alone be capable of clogging the filters to the point that the car wouldn't start at all (not even a sputter or rough start)? The prefilter looked clear, for what it's worth.

sleepstar · #12 08-30-2014, 07:39 PM

sounds like low fluid to me, the transmission should start in 2nd unless you're in L, same thing happen when you come to a complete stop and shift to L?

also rare for the lift pump to fail at only 194K miles i would think.

Strand · #13 08-31-2014, 10:21 PM

Quote:

Originally Posted by sleepstar

sounds like low fluid to me, the transmission should start in 2nd unless you're in L, same thing happen when you come to a complete stop and shift to L?

also rare for the lift pump to fail at only 194K miles i would think.

In my experience, the car's always started on 1st. I usually count three shifts by the time the car is done accelerating to highway speeds.

I hope that the fuel/injector pump isn't the issue. From what I've read, both parts tend to be extremely sturdy and should last more than 197k miles. That said, I'm having a hard time imagining what else could cause a complete no-start. The trouble here is that the diagnosis will have to be done remotely, as the car is in New Hampshire and I'm in New York. It's definitely going to be an adventure.

Strand · #14 08-31-2014, 10:28 PM

For more background info:

Car drove from Newark to New Hampshire (approx 300 miles), with fill-ups in New Jersey and in central Connecticut. Apart from the transmission oddities, the car drove and behaved completely fine all the way to the final destination in NH on Friday evening. The next morning, the car wouldn't start at all. Healthy cranking, but absolutely no ignition of any sort (which led me to believe that the engine was receiving 0 fuel, hence a potential pump failure).

leathermang · #15 09-01-2014, 07:38 AM

Try opening your fuel cap and see if it will start.