New Diesel Owner Questions - PeachParts Mercedes-Benz Forum

disqo · #1 06-19-2007, 11:54 AM

Hey Everyone,
Well, I finally bought a 1985 300TD and am now wondering what I should do with it to be sure it is in great shape. I have no real previous service records and was wondering what you veterans would recomend doing as far as general maintenance. The car runs pretty well, but does smoke a little bit when first started. The steering also seems to have a few inches of play when it is centered. I really want to be sure the car is taken care of preventably. I am looking to spend $500 to $1000 on parts and am mechanically inclined, so please don't hold back.
Thanks!

bodyart27 · #2 06-19-2007, 11:59 AM

if of unknown age:
oil & filter
air filter and check filter housing mounts
flush radiator and refill with mb coolant only
motor mounts
both fuel filters
belts
check brake pads - if need be - pads and replace old brake fluid

TheDon · #3 06-19-2007, 11:59 AM

change all fluids(oil,coolant[correct zerex g-05] transmission fluid, differential if you feel like going there), new filters all around (fuel, transmission, air), Valve adjustment (new valve cover gasket as well), Clean the banjo bolts and adjust the ALDA

barry123400 · #4 06-19-2007, 01:17 PM

Important without records or previous knowledge. You are mechanically inclined so the condition of the timing chain for stretch. Especially the chain guides for excessive wear as a chain guide coming apart can take the chain and do a real number on the engine. At the same time make sure your pump timing and cam timing are right.
You want all the cold start ability, good running characteristics and best fuel milage possible. The checks also are basically free to do yourself as well. Instructions are well done in the archives if there is any confusion just ask for clarification. Since the valve pan is off then check the valve clearances at the same time. A lot of these cars mechanicals have been ignored by a lot of previous owners as long as they ran they were ignored.
Since you only have dash gauges and no idiot light or warning system check belts, coolant hoses,oil cooler rubber lines . You want nothing failing as car is underway. Also a brake fluid flush and coolant change to the recommended type is good as well.
Possibly if the car has the green antifreeze and it is already acidic with age. You do not have an aluminium head so it is not as critical. Since it is thought the green anti freeze attacks the german plastic necks on the radiator. I really do not know if that is conclusivley proven though.
It is still a good ideal in my mind. Flush and clean out the block and radiator as well of course in the coolant change. The block has a plug.
At least check the differential level and check condition of cv boots for cracking or leakage. A good total checkover makes good common sense to me. Really is cost efficient anyways.
Your steering box will probably allow some adjustment as mentioned in the archives again. Also check all your front end components for any unusual play as well first. Nobody likes a sloppy steering system although this car may never be as tight as a steering rack example. Others may disagree.
Always good ideal to see new people join the site. The site makes ownership of these cars easy in comparison to it not existing. Welcome to the site and looking forward to your thoughts.
I just hope you are not one of these guys that never changes his oil. I was going to say gets his oil changed regularily but thought better.

We do not need a new convulted oil thread either. Find one in the archives for your own entertainment when you have a little time. They tend to be more polarized than a battery.

. The above things I mention can keep you going for a little while.

vstech · #5 06-19-2007, 01:29 PM

you have an 85... this is the only year for a few items. first, does your tach work?
second post a picture of your car.
third post a picture of your instrument cluster. and zoom in on the speedo. it would be nice to know the correct part # for the 85 speedo. as with it's 2.88 rear ratio ONLY an 85 speedo will work. also ONLY an 85 Tach will work. as the pre 85 tachs are driven differently...
check the sunroof slide, clean and lube. check the door/sunroof seals, replace as needed. check the drains all around. the doors have drains too. pull the battery and tray and CLEAN well. get that rust before it gets you! also the hood spring trays they collect and plug the drains causing RUST@! basically look over every last inch of the car for rust and places for water to drain. clean clean clean.

TheDon · #6 06-19-2007, 01:48 PM

Quote:

Originally Posted by vstech

it would be nice to know the correct part # for the 85 speedo. as with it's 2.88 rear ratio ONLY an 85 speedo will work..

123 542 27 57

barry123400 · #7 06-19-2007, 08:50 PM

One other thing usually neglected and painful to repair on 123s. The front hoods hinge pins where they attach to the body sheet metal. Usually just need a drop or two of oil. If the pin seizes in the bushing and the bushing rips out of the sheet metal it is not a fun repair in my opinion.
Or at least I have found them awkward to repair and just found another bushing already torn out on one of my cars the other day. Many times they have never seen any lubrication for a very long time. A couple of drops of oil once a year will keep them free and lessen wear. Actually an odd thing but more 123 specific than any other cars I have ever owned. I almost bet about half the guys reading this have never lubricated there as they are out of sight almost and usually out of mind. Until one rips out.

Stevo · #8 06-19-2007, 09:06 PM

Lots of good suggestions. One of the things I always find needing too be done is, clear the water drains below the hood springs. find the driver side one then you'll be able to locate the pass side one. Its a good idea to pull the battery out and check the tray. If it looks bad check under it. (its apt too look worse).

Stevo · #9 06-19-2007, 09:36 PM

I am right in the middle of "bringing one back" right now. It a manual 82 240D, Typical case of so much wrong the owner couldn't deal with it and sold it to me cheap. Anyway here is what I did which is pretty topical
adjust valves and check chain stretch
change oil (Delo 15/40) and filter + filter stem O ring
steering pump filter and fluid change
Swap passenger and driver seat
replace blower motor
replace hazard switch
replace fwd passenger side door class, regulator, check strap, and panel
New hood pad
I have yet to ....change out brake fluid
Install new release bearing, inspect clutch

Usually you have to fix the odometer and while your in there put a jumper wire on the dash light rheostat and change out all the dash bulbs that are out. On this car none of that needed too be done, very unusual

Also be sure and check under the fuel tank and make sure the hoses are not leaking.

solostyle · #10 07-26-2007, 05:04 PM

I recently bought a 1985 300TD as well. I just wanted to ask some clarifying questions about things mentioned in this thread:

Note: I edit this as I get more answers.

coolant: Zerex G-05 50/50 with water

transmission fluid and filter: Apparently any Dextron ATF will do. Takes around 6.75 quarts, but check after 5 quarts. Whatever filter fits also will do, may need to special order it.

power steering fluid and filter: Same fluid as for the transmission. Doesn't take much, check the dip stick. Going to use a siphoning technique, or get a pump of some kind.

rear differential fluid change: 85W-90 or fully synthetic 75W-90 works. Takes 1 quart and less than 1 cup. The pump-and-hose method used on dieselgiant's site (here) looks good. Probably find one at a Petsmart or the top of a soap bottle.

brake fluid: DOT 4. Found it!

air filter: Replaced this today. Simplest thing ever. The 3 rubber mounts under the filter housing are soft and look amazingly perfect for such a old machine. Need to replace the clamp that connects to the top of the engine valve cover.

The more I work on this, the easier it's getting! The rotor looks a little messed up. There's a lip on the edge, which suggests that the brake pads are eating away at the rotor. I'm not sure if I should go ahead and replace the rotors, or get a different kind of brake pad and replace all of them, or both.

Stevo · #11 07-26-2007, 05:28 PM

First thing you need too do is get an owners manual. All that stuff is basic maintenance items. If the car didn't come with one there is a site you can order it for under $20. Maybe someone around here knows or Google should turn it up. Congratulations, good choice for a first car, A 240D was my daughters choice.

solostyle · #12 07-26-2007, 05:50 PM

Thanks! I have an owner's manual, actually. Oh you're right, it does mention how much fluid is required for each fluid.

I even have the factory manual that came on a DVD for $50. It doesn't go through the actual steps for doing a lot of this stuff. For example, I spoke to a guy at Autozone about how to change the coolant (zerex g-05, as TheDon said). He said to put a whole thing of coolant in there (didn't say how much that was) then fill the rest with water. Turn the engine on, wait for it to drain and keep adding more water until it stops draining. Is this accurate?

I could really use a diagram of everything under the hood. I took a bunch of pictures, I might just post them, labeling everything I know, and maybe someone can help with the rest.

A bigger newbie task
I'm also going to be replacing the glow plugs (pencil type). I did the whole diagnostic that everyone talked about. The relay works, the light on the dash works, the fuse is in perfect shape, the battery is excellent, the continuity all checks out, and the plugs have low (under .7 ohms) resistance.

But still the dash light doesn't come on, so I'm replacing the plugs. I found some OEM plugs at Autozone for less than $10 each. Couldn't find a reamer, but I could just use pipe cleaners (?). People on these forums talked about how removing the fuel lines helps, but I don't want to assume I know where those are, or what/how to remove them. Is it pretty simple to remove them? Can I just pop them off and pop them back on?

It's disappointing that the manual doesn't mention anything about this, and I haven't found any detailed descriptions on how it's done.

toomany MBZ · #13 07-26-2007, 06:12 PM

I have a reamer, fuel lines do just push on, pull off, if old, replace. Don't know why you GP light will not work, perhaps bad bulb, as the readings are good, may need to check voltage.

solostyle · #14 07-26-2007, 06:27 PM

The bulb isn't bad. When relay is disconnected, the light comes on. The voltage checks out at exactly battery voltage on all 5 sockets, and on the fuse. I guess when everything looks good but the light still doesn't come on during pre-glow, best thing is to replace all 5 plugs anyway. Maybe reaming the pre-combustion chamber will help the old glow plugs work again?

Can I borrow your reamer? Is the pipe cleaner idea not good?

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