I recently bought an 81 Wagon 300TD with 377K on it. It is a great car and I love it. The interior is in great shape, and the car amazingly runs really well. I think it must have had the engine rebuilt at some point, but I don't know. I'm driving it to work everyday and haven't had any problems and knew when I bought it that I would have a few things to work on if I wanted everything to work like it should. I have a few questions that I hope someone could help me with.

1. It seems the transmission shifts into 3rd too early. It doesn't really affect the driveability that much, but I would just like it to wind out 2nd a little more. When I am just easing through a parking lot or side street, it shifts fine when easy on the throttle. Conversely, if I am really getting on the gas - say 3/4 or more, it shifts fine too (although a little harder than I like - I usually don't drive like that). In addition, it doesn't seem to want to kick down to 2nd from 3rd unless I just about floor it. Kickdowns from 4th to 3rd are about the same. Is there anything I can adjust to change this?

2. It seems that I have to push the gas pedal way down, like halfway, before the engine notices it. It almost feels like I could adjust a cable or something that would make the gas pedal move the linkage sooner or something. Maybe this could be related to the transmission shifting thing??

3. The door locks work, but the engine has to be running, and the doors all lock pretty slow - it probably takes 4 seconds for them all to lock - they sort of ease down. I guess I have a vacuum leak somewhere probably. The person I bought it from said something about the door locks being plugged so the engine would shut down, but that doesn't make sense since they do actually work. I don't mind manually dealing with the door locks, but the back ones don't seem to like being unlocked manually, like they are sticking or something or don't want to let the vacuum off for me to unlock them. There isn't any detent or anything when unlocking the back door manually - they just kind of 'ooze' up for lack of a better word. I hope that makes sense.

4. The heater works, but I can't get any air to come through the center vents. It has the deal where you have to hit defrost for the fan to come on so I'm gonna replace the brushes in the blower, but I want to see if someone can suggest where to start on the climate system. It is the automatic system. Should I start with removing the control unit and resoldering the connections? Should I look at the electronic box above the dash? Where is a good place to start?

5. The cruise control doesn't work - this is the least of my concerns, but hoping someone could suggest where to start on this one.

6. My temp guage reads around 40 all the time after heating up. It does more UP to 40 or so, but doesn't go any farther. Is that normal?

7. What kind of oil should I put in this car? This is my first diesel and I love it, but don't know if it requires any special oil or anything.

8. The glowplug light on the dash doesn't light up. How can I tell whether the glowplugs are working of if the light is just out? I read somewhere that this light not glowing means the glowplug system isn't working. All the other hazard lights work so I doubt it is blown. It was a little hard to start tonight - took 3 tries. It is around 100 degrees around here now so no real starting problems yet, but when it gets cold I want to make sure the glowplugs are working. Is there anyway to just run a manual switch inside the car to turn on/off the glowplugs myself?

Thanks so much and sorry for the lengthy post. I have looked for a few of these things on the forum, but was hoping an expert on these vehicles could throw me something to start on.

Thanks,
Tom

Temp is between 40 and 80 - sorry about that discrep.

Welcome to the forum and the world of MB diesels.

For your central locking problem, I just went through this yesterday. The factory service manual has a description of testing the connections from the engine all the way back through the chain through a process of elimination.

You'll need a vacuum gauge and about 4 golf tees. You use the golf tees to isolate a suspect connection and get a unique vacuum reading. Assuming you only have one leak, you should be able to find the source line at the driver's side door, or if it's the check valve, in the engine compartment. It might be worth changing out the check valve anyway at that level of miles as it's probably pretty worn.

If the rubber interconnects are cracking, probably worth replacing these as you go along too. Mine were in pristine condition so I'm guessing they've already been swapped out once.

I think some other threads on this forum might already detail the process with photos. If not, let me know and I can send you the FSM pages with the test procedure.

As for your 2nd-3rd shift problem, I'm very interested to hear about the source as mine has that exact same behavior...looking into buying a transmission from a boneyard and rebuilding to make a nice replacement.

__________________
1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)

Thanks for your response!

I ended up finding some awesome info on dieselgiant.com. He has a bunch of how to's with pictures. I think I will check out the check valve tomorrow. I need to get a vacuum pump and guage to start on this. The door locks aren't really a biggie right now. I gotta get my glow plugs working first, then change oil, trans. fluid/filter, fuel filters, do diesel purge, valve adjustment, etc. just so I can start fresh from a maint. perspective.

I think on the trans it could be the green trans. check valve or maybe the little rocker tab things on the linkage. I am learning alot about the little odd and end things about these cars from this forum and other sites.

I'm sure there are a lot of worn items on the car with so many miles and I will be checking and addressing them one by one over time. The good thing is that I really think it is a solid car, even with so many miles on it. Of course there is some fear of it just crapping out on my after I spend time hunting down the little things, but we'll see.

If anyone else has any suggestions/comments PLEASE let me hear them!

Also, I was thinking of eventually getting those bosio nozzles at some point. You like them? Notice a difference?

huge difference with bosios. That was on my SDL though which was smoking and nailing. TD I believe is still on original injectors, but I'll change at some point in hopes of improving fuel economy.

And to do locks, you don't need a vacuum pump, just a gauge. It's useful, but you can evacuate the system by starting the engine. Downside is you may start engine many times.

__________________
1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)

My TD is smoking some on startup - probably because no glow plugs and of course the mileage. It also smokes a good bit when accelerating up the on ramp to the interstate. I'm hoping just doing some of the normal maint. stuff will clear up some of the issues as the engine still feels super strong.

Thanks on the vacuum pump thing - depending on how much they are I might get one since I plan on checking the whole system - I hate to restart a diesel that much - they are meant to run!!!

I tell you what - this car is butter smooth on the interstate. It is built like a tank. Even my wife said so when she first got in it. I think these old mercs are some of the best cars now. ANY car that can run that long and still be a good 'hicle is a nice piece of machinery in my book. I used to (and still do) badmouth european cars, but I think that I should just start badmouthing the newer ones. Quality wise - I currently think Japanese cars make the best vehicles from a pure reliability standpoint, but my 89 Camry has 270K on it and probably won't be anywhere near this shape if it could ever reach 377K.

Anyway, I'm rambling.

TF, Welcome to the TDT. It's a great vehicle. I was in your spot a year ago and, like you, I found that Diesel Giant was an enormous help. As you approach each of the fixits on your TDT, keep the KISS principle prominently in mind. IOW, don't go the most complex solution, because it's typically the simpler solution that works. Have fun with your new Benz.

Best regards!

I found these links to be enormous help

http://diymbrepair.com/

DIY Pages. Overview of current pages with links. W123 basis.

by now DieselGiant goes without saying.

I'll throw Brian Carlton out there too. He's been a big help in many cases, though he has yet to build his own site. Maybe just a matter of time .

__________________
1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)

Thanks for the welcome. Thanks also for the additional resources.

Yesterday I used the DieselGiant tutorial to check/change the glow plugs. Thanks DG! I got out the ohms meter and checked everything. I would have been completely lost without all the info online. It definitely takes longer than you think it will just by looking at the engine. Everything is very accessible - probably the best on any car I have had, but the blasted injection lines sure are a booger when messing with the glowplugs - I even went and bought an extension and a universal joint but could only get to a couple with this. It take a long time to get them out 1/8 turn at a time.

Anyway - I was so happy after changing them out - I did multiple pelvic thrusts that my wife thought was pretty funny. It cranks right up now - I mean like immediately. I drove it to work for the first time 3 days ago (3rd shift work) - and everymorning it has taken at least 3 tries to get the engine to light off - and smoke galore - right outside of my vp's office - pretty embarrassing to say the least - now it is like a new car - no smoke at startup.

I think the valve thing on the firewall that goes to the banjo bolt has been bypassed on this which I will have to fix so the motor doesn't overboost. I'm gonna really have to inspect the vacuum system in depth. I think it has been modified a little. One of the lines is plugged in the engine compartment.

Anyway - exciting stuff.

Just an fyi, fellow wagon head. Usually when you carpet bomb multiple questions in one post you don't get the answers to all your questions. You might want to post seperate questions for your issues, after of course exhausting the search function......

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

yeah - I figured that but went ahead and posted it anyway - just sort of did a "brain dump" to see what replies I'd get. Still searching through the forum for the various items and will post with additional things i need help on. Thanks for your comment!

Tom