Difficulty starting
 

My beloved w123 has trouble in the cold (California cold, in the low 50's). Every morning is a gamble on if it will start or not, usually it takes at least a few cranks. I got a new battery yesterday, hoping this would do the trick. It didn't. The guy at Sears also tested the alternator and starter and said they are all fine. What do you guys think?

I'm tempted to also buy a Jump Box (AAA gets her running quickly with one of these) but I am not sure which ones will be able to handle the big Diesel battery. But, being a student, I don't want to spend too much if I don't have to.

Thoughts? Thanks !

Sounds more like a glow plug issue. Does your glow plug light come on when you turn the key to on? If it does come on, are you waiting for it to go out before cranking it over?

I would check and test glow plugs first. Look here for a good how to... Mercedes Diesel Glow Plug Repair

X2. 90% of no-start or poor-start conditions are caused by a glow plug problem.

Yes, the glow plug light comes on, and yes I do wait for it to turn off before I crank it. The article posted does sound like my car - runs great once it's warm, but on a cool morning... Lots of smoke coming out of the tailpipe, runs a bit rough at first, and is hesitant to start.

I don't have a garage/tools/etc at the moment (again I'm a student away at school), but I do have a trusted independent MB mechanic I go to. About how much money can I expect this to cost (ballpark)? scenario 1: glowplug replacement, scenario 2: starter replacement

Thanks!

Will the engine turn over with the starter? What year model is the car?

If the starter motor spins the engine at what you remember to be normal speed, then it is most likely a glow plug issue as mentioned earlier. There are two types of glow plug systems, so that's why we need to know what year.

Best of luck with it and keep us informed. We can help you through this if you keep answering our questions.

The fact that the glow plug light comes on is not adequate evidence that all the glow plugs are working. You need to confirm voltage to all plugs when the key is in the glow position and that each glow plug is actually glowing properly. A rough and ready test for glowability is the ohm test for each plug but it is not definitive.
These tests can be performed in under 5 minutes using a simple digital multi-meter. Haror Freight will sell you one for under $5.

My first question also relates to the glow plugs. Are they the pencil or loop plugs? I am having similar issues on my 240D with the old series plugs and have some of the new style parallel pencil plugs on order to see if that cures my issue.

Another thing to check on yours is the correct adjustment of the valves if you have not already done so.

Gator,

Just making sure that you know you will need more than the pencil type plugs themselves to make the conversion. You will need bushings to fit them and wiring. You will also need either the control relay or a relay and switch to actuate them.

I know there are kits for making the conversion and that may be what you are already onto.

Hope this helps.

The retrofit pencil plugs need no bushings and the existing 123 series plug relay will operate the pencil plugs perfectly fine.

84 300D
 

The car in question is a 84 300D.

Where is Calif are you located, 55deg? must be SoCal. was 33 on our front porch @ 6am.

Along with GP`s when did you last have the Valve adjusted? this can cause a hard start in cold weather as well as the Plugs.

Mercedes Diesel Valve Adjustment Procedure

It will be pricy to have a shop replace the plugs and a valve adj. for what they will charge in labor and parts mark up you can get some good tools and DIY.

The DG link PSABOIC added and the one I added should get you up to speed.

Charlie

Check the Glow Plugs. Disei Giant has apictorial on how to and the Meter can be had at Harbor Freight for $5 or less when on sale.

Adjust the Valves if it has not been done recentely.

Synthetic Oil allows for faster Cranking.

You can ignore the Glow Plug Light and keep the Key in the Preglow position until you here the Glow Plug Relay Click off. If you do that you will get about 30 seconds where your Glow Plugs are on until the Timer inside of the Relay turns them off.

After that you can cycle the Key again and go for another Preglow Cycle of about 30 seconds. (This might seem wasteful concerning the Battery but the Glow Plugs get things hotter than cranking compression can make things and the Heat is right in the Precombustion Chamber.)

You enjoyed that did ya'?:D

GlowPugs Change can be done anywhere by anyone who has ever turned a wrench before. Two tools required, 8mm combo spanner for the wire nuts and one more for the GPs (18mm on mine but i'm sure different on yours). 12mm IIRC but i'm sure someone else can chime in with that.

The GP light is NOT the end all word on GP health. Only way to know 100% is to hook 'em out of the car to 12v and watch 'em GLOW. Should be just the tip getting white hot.

Valves out of adjustment could also be a likely cause of your starting problems. Do you know or have a record of the last time this was done?? It is routine maintenance for these engines.

In your current situation with being at school, you'll probably have to have the mechanic do this job for you. Also a very easy job but it can be a little tricky for a first timer.

I used to pay my mech $90 to perform this service. about an hour of shop labor and the cost of a new valve cover gasket.

Do you have a Block Heater?? 50 degrees is well warm enough not to need it but it could help you get started easier if you are having a GP or Valve clearance issue.

Yes.:D

Thats what I ordered from "the source" if you know what I mean :D

It may be a little expensive but it has everything I need to get it converted over to the new plugs. Not sure if I will use the included relay or not just yet or keep the one in the car since it will work.