I have both a 1985 300TD and a 1983 300SD, both have weird shifting issues.... The 300SD just started to show off issues a few months ago (I've had it for maybe 6 months).

It seems that after I am driving and show down to a stop at an intersection, if I push too hard on the pedal, either it jerks when it shifts to 2nd, or the engine revs for a half second before it picks up into 2nd. Both situations happen about the same frequency. I am able to avoid the weird shifting if I simply accelerate slowly enough into 2nd gear. There is no other known vacuum problem - the heating ducts, ignition, brake booster, power locks, etc all work without a hitch. Also, any hard shift is usually only when it's colder or just starting out, and after a while, it disappears. I haven't changed the transmission fluid, but when I bought the car 6 months ago, it was a bright red color. I don't know what the fluid status is like right now, I'll check it in the morning.

How am I supposed to start/warm up the car in the cold (<40 deg F) before driving off? Should it sit for a few minutes idle? I used to do a trick on my older 300SD where I would hold down the accelerator pedal slightly to warm up the engine slightly for 30 seconds before letting it get down to idle - otherwise it might cut out, depending on the temp outside. I've also been told that you can cycle the glow plugs 2-3 times for 30 secs each. Is that any different than holding the engine above idle? Is there a right way vs a wrong way to start the car in the cold, and before driving it off? Is it normal for it to drive slow/rough when it's cold out for the first 10 minutes? I understand that the engines are versatile, but I don't want to inadvertently be abusing it.

I also notice a similar problem with my 300TD, but this always happens at approximately 40mph (2nd to 3rd gear?). It revs up for a good second and then finally picks up in the next gear. I just replaced the transmission fluid, and it very likely could be vacuum related. Besides hard shifting, the ignition cutoff doesn't work as expected (waits 2-3 seconds to cut out), so I'm wondering if any other vacuum item (besides the relay thingy that hooks to the side of the transmission) has something to do with shifting, air intake, etc. I did notice that there has been some oil in some of the vacuum tubes, but otherwise cleaned out the thicker vacuum tube that goes from the intake/turbo to the side of the fuel injection pump (that uses the banjo bolts).

They may be unrelated issues.

The 300SD is my daily driver, so it's more of a concern. The last 300SD I had always had hard shifting and after a year and a half, something inside the transmission broke and it got stuck into neutral/park. Am I maybe doing something wrong with how quickly I accelerate?

Thanks,
Tomas

B2 Actuator needing to be replaced? There's a actuator that breaks that will prevent shifting in first gear I think.


I'm still new to these mysterious cars though

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Java Developer/Linux SysAdmin

Current:
*1984 300D ~200K,1989 MR2 250K, 2012 Ford Fusion 4.5K (fiance's car to replace the uber-unsafe cavalier)
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Past: 1998 Chevy Cavalier ,2005 Saab 9-3 2.0T, 1996 Mazda Protege, 1974 Porsche 914 2.0, 1997 Land Rover Discovery 4.0L/5Speed, 1995 Jeep Wrangler

What is the B2 Actuator? Is that internal to the transmission? Outside? I've googled "300SD transmission actuator" and all I see is info about vacuum items.

The flare in the TD is unlikely to be caused by a vacuum leak. Vacuum leaks mean the transmission is getting less vacuum and when that happens the shifts get harder instead of flaring.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The B2 piston in the transmission is the piston that engages 1st gear. What happens is the spring breaks (I think) and doesnt allow shifting into 1st gear.

I havent had to do this yet, but it doesn't look impossible to do.

Vacuum issues (like I have) would only cause flaring if its hooked up incorrectly. Lack of vacuum would cause teeth-jarring shifting. If the other gears dont flare then you need to replace this guy.

How to Replace Your Oil Cooler Lines

__________________
Java Developer/Linux SysAdmin

Current:
*1984 300D ~200K,1989 MR2 250K, 2012 Ford Fusion 4.5K (fiance's car to replace the uber-unsafe cavalier)
----------------------------------------------------------------------------------
Past: 1998 Chevy Cavalier ,2005 Saab 9-3 2.0T, 1996 Mazda Protege, 1974 Porsche 914 2.0, 1997 Land Rover Discovery 4.0L/5Speed, 1995 Jeep Wrangler

By the way, this guy needs a new website or some help managing this one...

Even though its called "how to replace your oil cooler lines" its talking about B2 issues.

__________________
Java Developer/Linux SysAdmin

Current:
*1984 300D ~200K,1989 MR2 250K, 2012 Ford Fusion 4.5K (fiance's car to replace the uber-unsafe cavalier)
----------------------------------------------------------------------------------
Past: 1998 Chevy Cavalier ,2005 Saab 9-3 2.0T, 1996 Mazda Protege, 1974 Porsche 914 2.0, 1997 Land Rover Discovery 4.0L/5Speed, 1995 Jeep Wrangler

There are several ingredients to good cold-weather starting:

1. Fresh or correctly-functioning glow plugs
2. Supplementary heat for the engine and/or battery
3. A starter that's turning fast enough
4. Good connections at the battery terminals
5. For severe cold weather, synthetic oil
6. Decent compression in your motor, to begin with

EDIT: in addition to 4, it's assumed the level of electrolyte has been checked and topped up in the battery as needed... and the battery isn't more than 4-5 years old and is properly charged.

If you are doing prolonged cold weather starting you really should have a block heater, inline coolant heater, and/or synethic oil in the crankcase. It's natural for these cars to have increased issues with cold-weather starting as they age. If your glow plugs are more than two years old, or if the starter sounds like it's turning slower than it ought to, those can be contributing factors as well.

If you haven't looked at your battery terminals lately, pull them off and use some sandpaper (or a terminal cleaning tool) to polish up the terminals and both cable connectors. Dirty terminals can make a huge difference when it comes to turning over these diesels on cold days. A plug-in battery blanket or heating pad will preserve your cold-cranking amps on very cold days when you may need some extra glow time or cranking to get it to fire.

Yes you can cycle the glow plugs several times, though I wouldn't wait 30 seconds each time. But you shouldn't have to do that until it's really cold outside, below 5-10 degrees farenheit.

If you need the keep the revs up on the 300sd when very cold to prevent stalling, then I would think your idle is set a bit low. (I had an '82 SD that did that, and I had to keep the idle low as it was the only 'sweet spot' I could find where it ran smoothly.)

Side note: Have the fuel filters been changed recently?

Personally, after starting I wait for the temp gauge needle to reach the 40 mark before I slowly drive off (slow mostly for the benefit of the transmission, which is still cold). After startup I try to keep the revs under 800 for the first while. I limit my throttle for the first few miles. My rule of thumb is that if you don't feel heat starting to come through within a few minutes of driving off, then you moved the car off too cold. Just my benchmark....

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Is it ok for there to be a slight kick in shifting (especially cold), or is that a sign of something problematic? I just don't remember if it would go away completely or if it's okay to have a slight kick while shifting.


Driving today, the car seemed to have the obvious flare between first and second, maybe for the first half hour of driving. After that, it seemed to have a slight kick to shifting from 1st to 2nd, though it wasn't too hard that I think maybe it's normal? I checked the trans fluid and it's still pink.

Is there a serious risk of damage with the piston seal? I'm wondering if the issue can wait until I have some free time (ie a few months from now), if the problem will become progressively worse, or if it will just happen suddenly. It's been about a month now.

My 300TD flares as well, but it's always at 40mph, ie 2nd to 3rd gear, not 1st to 2nd.

Is the issue with the B2 piston seal possible for my older car getting stuck into neutral/park? I drove it off one day at an intersection and heard some jingling metal from underneath (ie the tranny) before the whole car stalled. It was jerking a bit and I pulled over and then the whole car died. I could start the engine back up, but it was stuck in park or neutral (and even shifting from park to neutral was a bit delayed). The jingling metal makes it sound like a gear broke apart inside, perhaps from the hard shifting I always had, after a while.

Hi Thomas, you are describing a number of symptoms on two different cars in each post. From experience I would suggest that you ask one or two clear questions in each post (and stick to one chassis for each posting), and ensure that the title of the post reflects what you want to find out, as much as possible. (Voice of experience.) You will get better and more responses that way....

Some commonsense observations: You should not be too concerned about the transmission changing behaviour in Canadian winter temps. The hard shift on your SD mimics what my first SD did in the winters. The second SD I had I ran with the vacuum control disconnected anyway, so it shifted hard all the time.

The 'flare' you are describing in your 300td is very common on those transmissions. You can try to adjust it out through the vacuum controls but it's an involved procedure and may not be something you want to do in Canada in November.

Make sure your fluid is at the correct level and clean in both cars and just drive them -- that would be my general advice.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

And from what I know about transmissions, a transmission that shifts harder is in better shape than one that flares between gears. Think about it this way....think of a automatic transmission as one that (loosely) resembles a bunch of tiny manual transmissions stuffed into one box. If vacuum weren't involved in how the shifting occurs, then one that shifted hard would mean the clutches arent worn. If they shift too soft, then thats bad.

Having a slight kick is what i strive for. Less wear on the clutches. The other day I fixed a bunch of vacuum problems, and my transmission flared like crazy between 2-3 and 3-4. I removed the vacuum and it shifts real hard until everything warms up, but it shifts firm after that.

__________________
Java Developer/Linux SysAdmin

Current:
*1984 300D ~200K,1989 MR2 250K, 2012 Ford Fusion 4.5K (fiance's car to replace the uber-unsafe cavalier)
----------------------------------------------------------------------------------
Past: 1998 Chevy Cavalier ,2005 Saab 9-3 2.0T, 1996 Mazda Protege, 1974 Porsche 914 2.0, 1997 Land Rover Discovery 4.0L/5Speed, 1995 Jeep Wrangler

I only mention my older 300SD because it had hard shifting for a year and a half and then something broke inside and I wasn't sure if it was related to the vacuum modulator being disconnected for all that time. I wouldn't want to disconnect a vital part that would cause the transmission to get damaged on my running 300SD.

Is there information somewhere about the vacuum adjustments to minimize the flaring?

I only mentioned my two cars because the issues seem related.

I actually live in New Jersey, I don't think it's nearly as cold as Canada, maybe it's been 35 deg at night lately, and the worst it gets is maybe 5 deg.

It's around 50 degrees or so in the day lately, so doing work on the car during the middle of the weekend days isn't an issue.

Ok if you want to work on it now, more power to you.

You need to first check that you are getting normal output from your vacuum pump and that all of the fittings (rubber y-joints, etc) associated with your vacuum hoses are still sealing tight and not dry-rotted and potentially leaking.

To start, disconnect the main vacuum line at the brake booster inlet and use a mityvac or vacuum gauge to check output. It should be 19-22 Hg. If that is okay, you can move on with diagnosis/adjustment. If it measures under that, your vacuum pump needs attention before you do anything else.

Here is the main thread for transmission vacuum issues:
It's CRITICAL... how you set your transmission's vacuum system on your diesel MBZ...

You should also read this very extensive collection of transmission info:
DIY W123 Transmission Diagnose and Adjustment 722.xx OM 616-7 - Benzworld.org - Mercedes-Benz Discussion Forum

Edit: I just went back and reread your original post and noticed your reference to other vacuum issues. You really need to make sure you don't have a vacuum pump issue or vacuum leak, before you do anything else.

This may be helpful:
Mercedes Vacuum Troubleshooting

Good luck with it.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

So until I can get that repair done, is it better to leave the vacuum modulator as it is (where it flares 1st-2nd when cold), or simply disconnect the modulator from the vacuum system altogether (creating a hard shift no matter what)? Will the modulator being disconnected cause transmission damage eventually? Ie if gears/etc (tranny internals) are banging each other too hard, over time, rather than smoothly moving in and out.

The vacuum modulator controls shift quality and as such I regard it as something there to make the driving experience worthy of the original sticker price of these cars.

I don't believe that driving with it disconnected has any detrimental side-effects. I personally like firm shifts, though I did find that the two cars I drove with the vacuum modulator disconnected shifted very abruptly 1-2 in very cold weather until the fluid was warmed up. I counteracted that by being careful with the throttle at those times.

However, I think that others on the forum believe it's best to have the modulator working, over the long term. I really don't know if they or I have any hard evidence one way or the other.

I'd suggest you try driving for a week with the vacuum line disconnected and make your own judgment.

BTW, sorry I don't know how I got the idea you were a Canuck. Doh.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22