Hey guys,

Just got my first w123 today. I love this thing. It's brilliant. haha Mechanically, I think it's pretty much good to go. I have a couple things I'm not sure on, but I think it's because I'm new to this particular type of MB. It's a 1984 300D turbo. I'm coming from a 1974 450SE, slightly different vehicle.

The glow plug light with either come on for a second then shut off, or not come on at all. I usually wait 10sec and it turns right on. However, I'd like to figure out why the glow plug light doesn't function properly. If I remember correctly there was a recent thread with a similar issue so I'll be sure to browse that, but if someone knows some helpful info to look into, feel free to refer me to it.

The dash warning lights... When the parking brake is applied, the brake light lights up very bright, when I release the brake, the light gets slightly dimmer, but it still definitely lit, and the brake pad light, the battery light, and the fuel warning light also stay on all the time. Where do I began with this? I looked for an answer online, and saw that it could be the alternator. Is this true? Can anything else cause this? And if I take the car to my local auto parts store, would there little alternator test tell me if the alternator is bad? I also read that a lot of times the alternator not working is due to the brushes or something which can be replaced and might fix the issue. Is this true, and is there any way to tell if this is the issue besides replacing the part? haha

My interior dome lights and hazards don't work either. Where can I start checking for this issue?

It looks like the sunroof rear seal could use replacing, is there any special trick to getting to it?

Both brake lights light up, but one is dim, what can cause this? If it were just out, I'd figure a new bulb. Could an old bulb cause it to be dim?

The brakes work, but I believe they probably need new pads and rotors and could use a bleeding while I'm in there. I'm really big on good braking performance, so I'd like to get the best performing pads/disc for the price. And on that note, does anyone have some good pads to recommend? I can live with brake dust, I just want good brakes. haha


When I first start it, and go to get moving, it feels almost like it's missing at very low speeds(like below 10mph), but I know diesels don't really misfire. Is this just me not being used to old school diesels? lol


I'm sorry to drop so many questions at once, I basically made a list of the things I was needing help with and posted it here. haha I really appreciate any of the help you all can offer. I'm not new to MB, but I am new to w123 diesels.

Thanks again!

whiew! heck of a load to start on with the car.

I'd focus on the brakes first. no need for D&S rotors, aside from looking, but you'd need to change the wheels to see them anyway... a good flush, and bleed is a great place to start. the brakes are AMAZING on these cars. get them clean, and see how you like them stock.

no flashers, but do the turn signals work?

instrument panel lights all on. I'd start with an alternator check. likely it needs to be replaced, the brushes/regulator wouldn't cause those issues.
if you still have the 450se, the alt may fit as a test.

Fuses are KNOWN to cause odd issues, as are ground connections. pull the fuse cover, and look to see if any of the fuses are aluminum. change ALL that are. if any are corroded, you will need to clean the contacts with a pencil eraser.

also, it's best to start a new thread on each major problem you are having. that way you can focus on one repair at a time and we can follow along, and help without much confusion getting in the way.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

X2 on the brakes first and fuses.
Then maybe change the oil and check all fluids.
Manually inspect the rubber on the front end and all mechanical connections especially the axle assemblies, tranny mount, differential mount, etc...

Congrats on your Benz.

__________________
Codifex
1981 240D ChinaBlue (Got her running with a donor engine.)
1983 300DTurbo w/sunroof.
1984 300TD manual sunroof. (Electrical Gremlins)

GP light duration time is a function of temperature. PM sent with link for more info.

Dash warning lights. Yes, the alternator can cause the three lights to glow dimly. Or a problem with the cluster. Mine did this after I pulled the cluster and did maintenance on it. So I pulled it again, checked all the screws and the traces, then reinstalled it. The lights all stayed off. There are a few current threads on alternator regulators. You might get good info from a chain store's equipment, maybe not.

My dome light didn't work because the switch got dirty. There's Auto (with doors) Off and On. Cycle a few times, check all three positions. If no go, then carefully remove and clean. Check the rear dome switch on the console. I believe they're on the same circuit.

Hazards may be a relay. Try on-off a few times. There are a few threads on this. Do the turn signals work? The issues may be related.

Check all your brake lights and tail lights for the correct bulbs. Using the wrong (HD) bulbs in the sockets can generate too much heat. The size and shape are the same, so it's easy to think you can sub one kind in for the other.

Brakes are pretty good stock. Wheel fitment will be an issue based on offset and the steering arms. Drilled/slotted? Really? Okay....

Valve adjustment, filters, clean fuel, change some fluids.

Haha! I know, it seems like a lot, but the best part is, these are basically all the things the car needs. So it's not as bad. lol

Thanks for the tips on the brakes man. I figured the D&S rotors were overkill. I think I'll just stick to regular rotors. The D&S rotors were $130+ and weren't a major brand, I can get Brembo OEM type disc for $36 a piece. I'm going Brembo.

And yeah, I meant to throw that in, The signals work great, front and rear. But when I hit the hazards switch, I get no signals outside or on the dash. The power windows all work, the mirror control works, and I haven't gotten to try the speaker fader. Maybe the hazard light switch is bad?

And I was figuring that. At first I was confused because I'm used to gassers which will leave you stranded when the alt goes out, forgot the Diesels use a lot less electricity. I don't mind replacing the Alt if that will solve the issue of the lights all being on. I'll go ahead and check the fuses too.

That's a good idea, I think I'm going to edit my main post and just leave the major issues in it, I'll save the more minor stuff for later.

Yeah I'll get those sorted before anything else. I'll also probably do the fluids for good measures.

As for the front end, one of the best parts of this car was all the work the PO paid to have done on it. Among the many receipts, one of them was for a full front end rebuild replacing all of the bushings, another big one was a gearbox rebuild. I felt terrible for the guy, but at the same time, I got a great car. haha Thanks for the congrats! I drive my moms W210 a lot which I actually really like, then there was my w116 which I loved, but it needed a bit more then I could give it.

Thanks for the good advice. I'll be sure to look into all of that. And yes, I know, Drilled/Slotted, dumb. Thus why I decided against it. I was just asking though. Also, what do you mean wheel fitment may be an issue? They're Ronal R9's, and they're the right size and offset for w123's.

Start with replacing your fuses. They may look OK, but probably are the old lead type and the ends will wear down and through, and no longer make contact. Even if they're in good shape, if they're the old lead ones, get new copper ones at any local auto parts store and check everything for each fuse.

You probably need a new hazard switch. My '83 300D needed a new one, and it took five minutes to replace. I'm sure Phil can come up with a good OEM one for a good price, if you call him directly.

Throw some injector cleaner, or Lucas fuel treatment into the tank, and that may get rid of that "miss" at low RPMs. It'll also eat any algae in the tank. There are also other products recommended by MBZ that does the same thing.

Go for the"simple" and most common fixes. If those don't work, then you can upgrade to the next "fix."

Good luck with your new purchase.

Torie

__________________
1983 300D, the "Avocado"
1976 240D, 4-spd the "Pumpkin", SOLD to Pierre
1984 190D, 2.2L, 5-spd, my intro to MBZ diesels, crashed into in 2002

Thanks for all the help so far guys. I spent all last night and today doing research and getting a little more up to speed on what I need to do.So far, I have a list going,

Going to get new rotors, pads, and sensors. My current ones may or may not be okay, but I'd honestly just like to start with some fresh parts. Besides the rotors, pads, sensors, and brake fluid, is there anything else I should get?

I think I'm going to get some new glow plugs and put them in. They're cheap enough.

I'm gonna just replace the Alternator. It's not too expensive, and I'd like to just have a new one in there.

I'm gonna change the oil, heard good things about Rotella T, probably gonna go with that.

Change the fuel filters, I know about the clear one, and the canister one in the engine bay, but isn't there another one I should change?

I hadn't realized how simple a diesel purge is, but now that I know, I'm going to do that. A diesel purge will clean the injectors and stuff pretty well, right?

I also read up on the valve adjustment, I've done a good bit of work on regular gasser engines, and based on what I can do, I think I can do the valve adjustment really well, and I've heard it yields good results.

I'm going to do all of that on top of checking the wires, changing the fuses, and a few other things. Seem like I missed anything?

You'll want the schematic for your car and probably the vacuum diagram.

Your GP situation sounds like one or more of your GP are burned out.

You've got a project. Hopefully you'll enjoy it. Every problem you have described has been seen and discussed here a number of times. So as you progress you'll find those that can help.

I have a sort of checklist when I buy one. (I Own 4 of them)

1. Check all the fuses, and replace.
2. Check and replace the brakes. Cheap and easy to do.
3. Check ALL the vacuum lines. Replace All the soft lines, even if they are working. (I just don't like old lines) Get yourself 10 foot of vac line and it will do the whole job.

4. Run a can or 2 of Diesel Purge.
5. Clean out the Bango Bolts and connected lines.
6. Clean out/remove the EGR. (you can buy a simple kit to remove it here)
7. Test the Vac Pump. (should be putting out something like 22 bar)
8. Replace all fluids.
9. Replace ALL filters.
10 Do a valve adjustment and replace the valve cover gasket
11. Test the ALDA... Chances are the diaphragm inside it's fail and need replacing

12. If the car is an 85. I open up the KILMA switch and check for burnt connections and fix.
13. Test the boost using a boost gauge. IF the car has the KKK version of the turbo turn it up a little (I'm, finding that around 18 WOT is great). (If you have the Garret Turbo, you can do the same adjustment, but it's a lot more involved)
14. pop off the dash center (Climate controls area) and the switch panel above it. Test the Vac block behind there to check out the dash pods and see which are working. Replace the ones not or, at least cap off the bad ones so they are not leaking.
15.Manually open the center vents flap. you can still control the air though them via the vents themselves. having them open makes a huge difference. and that center pod is a RPITA to replace, so I just cap it off.
16. Replace required door seals, sunroof seals.



Start with the above stuff, you can do it all in a day. once done THEN start troubleshooting anything else you may have going on.

vac will put out 22" not bar... other than that, the list is great!

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Very good "list of things to do". Its a time consuming job but I have pulled the fuel tank out of every one of mine and clean it so I know I am starting fresh.

I have searched the forum to no avail looking for a good "after basics -better performance tune list" such as checking boost, checking timing, changing nozzles. Can anyone list what your boost and fuel press should be and the best way to achieve them. I don't want to add an intercooler or tweak my wastegate, I just want to get the most performance out of my stock 617s. And what should be checked and adjusted first after a valve job of course?

__________________

I LOVE CATS....AND FRIES

1981 300sd
1983 300sd
1985 300d
1983 300cd
1991 350sdl

There is a fuel strainer (wire mesh that can be rinsed clean and reinstalled, maybe a new "O" ring tho) located on the bottom of the tank, unless you have a sludge build up, I wouldn't worry about it.

__________________
83 SD

84 CD

I would add a dash of patience to the mix.

A good underhood cleaning, some quality penetrating oil and planned sequence of events can go a long way to stop a quick "I'll just bang out this filter change" from transforming into a Sunday evening "Help! It's three-quarters disassembled and I need to drive it tomorrow."

The brakes, for example: What happens if you can't compress the pistons to put new pads in? Can the car be down for a few days? Is the plan rebuild or replace if you discover a leak? Can you source new hoses locally? One-man or two man bleed, if needed?

Plan ahead. Clean and soak the parts before you turn a wrench, and review the "Resources" button in the upper right corner. There are a lot of excellent DIYs there.

Oh, and check those rubber fuel lines at the rear of the car, they tend to get overlooked and can be a source of air getting into the fuel if bad. (Not to mention leaking fuel)

AS addition to the list, I normally check the engine mounts now, replace any bad rubber exhaust hangers and make sure that the air cleaner mounts are there.

Here's a good tip.

Goto the dollar store. Pick up the house brand oven cleaner, get 3 cans of it. Its a buck a can. Get your engine warm and then then soak everything you can down with the oven cleaner and let it sit for about 10 minutes and rinse off. MAke sure to get under the engine, trans while your at it. Do not get any on your rims, it will take the finish off. Don't breath in the fumes. do this BEFORE replacing you vac lines, as I find the stuff can soften them. Anyways you'll have a nice clean engine when your done. which makes everything a lot easier to work on and see. You will get a little white residue on the aluminum parts. take a rag with a little oil and rub down the parts to remove and it will almost look new again.

This will of course also allow you to see where things are leaking etc.

Also, check those rear axel boots. IF any are ripped then the oil in them is gone. you can fill them with grease and be fine for a bit, but replace them asap. You DONT want the expense of replacing the actual joins due to them being ruined by running them dry.