My new (to me) 300TD - many questions - PeachParts Mercedes-Benz Forum

cavalierz · #1 09-13-2008, 12:22 AM

I just drove my wagon home 250 miles and it drove very nice...except for a few issues. First, the idle is rough, I think. It makes the car wobble at the red light. It has new motor mounts, so I don't think that is it. By the tach, it is idling at 5-600 rpm. Seems like that could be it. Also, it is shifting 1-2-3 very quick, and hard. is the bowden cable the likely culprit? Also, on the ride home, the high beams worked for a while then just quit, in fact, when I turned them on, the lights went out altogether, even the low beam. Finally, the cruise doesn't work and neither do the power locks. I assume it is vaccuum related, and that this could be the prob with the shift too?

JimmyL · #2 09-13-2008, 12:26 AM

Welcome to a fellow wagon owner, and congrats on your purchase. Also, bless you for not incorrectly referring to it as a 300TDT.

What year is your wagon? Makes a difference on some of your question.
Your idle is a bit low. Usually about 650-700 I think.
Buy you a Mityvac and get ready to dig in to the vac system. You will be there often.

TylerH860 · #3 09-13-2008, 12:31 AM

The guy knows alot more than me when I started one year ago.

I take it this isn't your first rodeo? (in the MB diesel world)

Jeremy5848 · #4 09-13-2008, 12:32 AM

The hard shifts and the door locks are both due to a failure in the vacuum system. You probably have a broken rotted, or disconnected vacuum line somewhere. As Jimmy says, you need a MityVac and a copy of the vacuum diagram from one of the links at the top of the page. It is a slow process to trace through the whole thing but that's what you need to do.

Biodiesel300TD · #5 09-13-2008, 12:43 AM

The rough idle could be two things. You said your idle is between 500 and 600. It should be up around 750. There is an adjustment you can make to raise the idle speed. Its on the passenger side of the injection pump. Between the pump and the block. You'll need a 14mm deep socket to loosen the lock nut, then there is a screw on the top that you can adjust the idle speed with. Then retighten the lock nut. The second option is the rack damper bolt. It may need some adjusting. Or may need to be replaced. I would raise the idle first and see what happens.

Your quick 1-2-3 shifts are caused by an improperly adjusted bowden cable as you said. I can't remember which way is needs to be adjusted, but I think you need to screw the adjusting screw out to make the shifts later. Turn it a 1/4 turn or so at a time then drive the car. And keep adjusting until the shift points are a little to your liking.

Sounds like your head light issue could be in the combination switch you use for turn signals and brights. I had one once that would turn the lights off when you turned the signal for a right turn. I would play with that a little, try turning the lights on then try switching to brights slowly and see if the lights cut out.

Depending on the year the cruise could the a vac problem or a cruise amp problem. It's really rare that cruise works on these cars.

The door lock issues are vacuum related. You probably have a leaky actuator in one of your doors, a bad connector, or the pump isn't pumping enough. Like stated before you'll want a mity vac to troubleshoot the vac system.

cavalierz · #6 09-13-2008, 01:04 AM

Well,
I have a mityvac already, which is a good thing i guess. I really don't know my you know what from a hole in the ground when it comes to these cars though. Its my first mercedes and my first diesel anything. I kind of had done some reading on this site and others which allowed me to at least ask a question that was better than super generic. Thanks for the prompt replies. I am so excited, I almost want to head out there right now 12:59 est and work on it. I guess I'll try the idle first since it seems so low.

I forgot to mention that the odo works, but only intermittently.

I am not really afraid of any of this stuff though, since it runs so great on the highway. One other thing, how high will this thing rev. I felt like I was really abusing it to go 70 - maybe it just felt that way since I had a preconcieved notion that diesels were low rpm chuggers. It was at like 3100 at 75, give ot take a few revs. Does that sound about right.

Oh, and one last ?, I paid 2400, it is an 83 with 269xxx miles on it. Hopefully I didn't overpay by too much. Only one rust spot - drivers rear rocker, if that matters

TylerH860 · #7 09-13-2008, 01:35 AM

Your Rev levels are normal.

TylerH860 · #8 09-13-2008, 01:40 AM

Quote:

Originally Posted by cavalierz

Oh, and one last ?, I paid 2400, it is an 83 with 269xxx miles on it. Hopefully I didn't overpay by too much. Only one rust spot - drivers rear rocker, if that matters

You did great for your first purchase, if the car runs down the road and the rear-end sits up nice and high. I slightly overpaid for my first one Ol' Turbo, and stole my wagon Norm.

dieselnutnj · #9 09-13-2008, 03:23 AM

rough idle can be caused by a host of problems, ranging from a bad injector, to improper valve clearance to low compression in one or more cylinders. My wagon has done that wobble for years, it's a joke amongst my friends and I. Start with the basics, and check your valve adjustment. The clearances vanish over time. Amazing things happen when the adjustment is corrected.

Odo's.. common as the wind for problems. I have NEVER bought a Benz with a working ODO.. my latest.. a 190E.. needed surgery to fix it too. If your fairly handy.. you can remove the cluster, remove the speedo, and if you study it. .you will find a pot metal or brass gear that needs to be tightened back up on the shaft. I've actually slid the shaft out, and "nicked" the shaft to give it some friction.

Cruise on these... usually winds up being cracked connections in the cruise amp located up under the dash between the emergency brake and regular brake pedal. If your handy with a soldering iron.. have at it! I've found that if you take a tooth brush and acetone to the solder side of the board first and clean the coating off.. soldering is much easier. go one at a time, and take your time.

Door locks.. everyone who owns a Benz should have a mighty vac!!! It is as handy on these as a 10 mm wrench! The vacum system is not hard, and right under the floor mat on the psgr side will be a "t" connection that will allow you to isolate at least the front psgr side door and the rest of the system.. and then just in the area of the rear seat.. u guessed it.. another connector for the rear hatch, fuel door, and psgr doors. Make sure that it isnt as easy as the lines popped apart at any of those junctions. Use your mighty vac to check the diaghphrams in each door.

Hope it helps. Have a ball.. these are REALLY fun cars to work on!!!!!!!!!!!!!!!!!!

Rick
W2ICA

Bio300TDTdriver · #10 09-13-2008, 11:15 AM

Quote:

Originally Posted by JimmyL

Welcome to a fellow wagon owner, and congrats on your purchase. Also, bless you for not incorrectly referring to is as a 300TDT.

What year is your wagon? Makes a difference on some of your question.
Your idle is a bit low. Usually about 650-700 I think.
Buy you a Mityvac and get ready to dig in to the vac system. You will be there often.

I'll venture a guess on the year. It is not a 124, so '81-'85. How about 300TDt? Is that acceptable?

JimmyL · #11 09-13-2008, 12:07 PM

Quote:

Originally Posted by bio300tdtdriver

how about 300tdt? Is that acceptable?:d

NO!!!

Biodiesel300TD · #12 09-13-2008, 12:27 PM

For those of you that may not understand Jimmy's irritation, let me explain. Starting in 1981 all the 3.0L diesel wagons that came to the US had turbos so calling any wagon from 1981 on a TDT is redundant. It is also redundant to call any 300D from 1982 on a DT. They are all turbos in the US from 82 on. And calling a sedan a 300TD because it is a turbo diesel is just out right wrong and offensive the the true TD owners.

Chad300tdt · #13 09-13-2008, 12:39 PM

Quote:

Originally Posted by Biodiesel300TD

For those of you that may not understand Jimmy's irritation, let me explain. Starting in 1981 all the 3.0L diesel wagons that came to the US had turbos so calling any wagon from 1981 on a TDT is redundant. It is also redundant to call any 300D from 1982 on a DT. They are all turbos in the US from 82 on. And calling a sedan a 300TD because it is a turbo diesel is just out right wrong and offensive the the true TD owners.

Agreed ... and on top of that, there are MANY threads archived here, where people were confused or gave incorrect advice because the OP was using an incorrect designation.

I am one of Jimmy's coverts. I too used to use the incorrect designations in an attempt to let everyone know I had a turbo. I now let my screen name stand as a reminder to myself of where I began and of Jimmy's "gentle" correction.

JimmyL · #14 09-13-2008, 12:49 PM

OCD isn't just a disorder, it's a way of life......

Bio300TDTdriver · #15 09-13-2008, 12:51 PM

Quote:

Originally Posted by Biodiesel300TD

For those of you that may not understand Jimmy's irritation, let me explain. Starting in 1981 all the 3.0L diesel wagons that came to the US had turbos so calling any wagon from 1981 on a TDT is redundant. It is also redundant to call any 300D from 1982 on a DT. They are all turbos in the US from 82 on. And calling a sedan a 300TD because it is a turbo diesel is just out right wrong and offensive the the true TD owners.

Oh, I understand his irritation. I just think it borders on a neurosis.

Just for your info the E300 diesel in '95-97 was not turbo charged. So not all diesels from MB were turbo charged after '82.

TDT is so widely used that it is accepted by some people north of Texas.

Now when you call a sedan a TD, that is just ignorant.

The opinions expressed above are not meant to annoy any forum members, well maybe Jimmy, but I like him.