new (to me) 240d won't start
 

Hi I'm new here, so bear with me.

I bought a 78 240D last week. It test drove well on two occasions, then drove 60 miles home on the interstate and did great. But then it wouldn't start the next morning and i haven't been able to start it since.

I've searched around here a little. I've checked the glow plugs and looked for fuel leaks. I repalced some of the fuel lines that looked older and bled the fuel system. I replaced the battery cables. The glow plugs are filament type, and they are all getting volatge, but i don't know what kind of voltage is normal. I can also see a small pocket of air in the fuel prefilter that i can't get out, is this ok? or should i have absolutly no air visible?

Any advice would be much apppreciated.

John

Air in prefilter
 

A little air in the prefilter is not a problem. Mine ('80 300TD) always has it. I've changed it several times when it got clogged, and I always fill the new one with vegetable oil (I'm burning WVO blends) usually including a little air. No problem. Lots of questions like yours have been discussed many times here; further searching is encouraged. Good luck!

Welcome aboard.

Just went out and looked at one of my diesels to confirm what I remembered about the pre-filter and air bubble. Right or wrong, it has had an air bubble at the top since I have owned it. Runs good. Of course someone may come on and say there shouldn't be one then I'll have to check mine too.

I believe the test for the glowplugs would be resistance. When you went to start it, did you have a glowplug light showing on the dash (yellow on my two)? After they go out I usually wait a total of 30 seconds before engaging the starter. Did it turn over at a reasonable rate?

Is it spinning over, but not starting?

Take the Fuel Cap off and see if you here a vacuum when you do. If so, the tank vent may be clogged and the fuel is not getting pulled up to the IP. This is a common problem with cars that have set up for a while.

Is the prefilter clear or does it look dark? May have clogged filters.

Any fuel leaks? If so, it may also be pulling air into the system.

Touch the resistor wire between the first two glow plugs (cyl.1 and cyl.2) very quickly after glowing the plugs. Do not grab it, but rather brush your finger across it very fast. Is it hot, if not you have a glow problem. If it is, you may still have one but it's less likely.

These are just a few things that are easy to check.

Copied this from a quick search on glowplugs & ohms.

"Any GP that doesn't read about 0.7 ohms is suspect. Do the 12V test (across battery terminals) on any GP that doesn't read 0.7 ohms. Replace any bad GP."

The search had 4-5 threads regarding 240D glowplugs and I think I saw how they were testing the relay.

From what I have read, you need to know if your glowplug indicator light on the dash appears to be cycling correctly.

Seems to crank at a reasonable speed... until the battery gets discharged. I've been recharging with a charger. It cranked fast enough to start it when i test drove it anyway. Seems to want to start, its smoking and feels like it starts to fire but doesn't catch.

I saw a tiny amount of fuel on the top of the filter after the drive home, thats what got me replacing fuel lines, i think i got rid of that problem. i will check the fuel cap, but it does seem like fuel is moving through the prefilter (which is clear, btw). perhaps not fast enough.

The wire between all the plugs is glowing red after heating. and the light seems to be cycling properly.

I thought the resistance check only applied to pencil type glow plugs, so i filtered out those threads... am i wrong?

John

did you remember to
 

Prime the system after you replaced the filter?

yup, pumped the hand pump until i got out as much of the air as possible and i got a constant squeaking noise...

Hmmm
 

This would be a good idea.
http://www.peachparts.com/shopforum/showthread.php?t=107229

For now, this is what you need for testing.
http://www.peachparts.com/shopforum/showthread.php?t=106447

Speed
 

Speed is critical for cold starting.
If the starter or battery are getting weak, you will have a very hard time starting.

Gp Ok
 

I rechecked the glow plugs and they sound ok, according to this link: http://www.peachparts.com/shopforum/showthread.php?t=106447

I get a steady decline in voltage across each plug, about ten at the start and 2 across the last plug. it seems the plugs are working according to everything i've seen so far.

The battery is new and holds a full charge.

I don't really have a good sense for the starter, so a slow starter seems like the best bet so far.

I'll go out and tinker with it somemore.

Also, no vacum when i open the cap.

Ok
 

The starter on my 1985 300SD cranks at 700 RPM.
If yours does not crank idle speed, it is getting weak.
I have replaced many starters that the diesel owner swore where just fine, then where shocked at how fast the new starter cranked.

I like the hard data
 

I like having hard numbers. I ran out to the car to check the cranking speed, before i remembered that this is an automatic and doesn't have a tach. Is there an easy way to hook up a tach? i don't have an optical tach, and all the aftermarket tachs i've seen hooked up to the ignition system on a gaser... hmmm. like i said, i don't have a good sense for this starter, i know it started fine when i test drove it, but that was 2000' lower and in a warmer enviornment, and the po probobly warmed it up first. i'll look at the starter a little bit harder. thanks everyone.

I may be off on this however someone will correct me and we'll both learn . . . I have a good commercial grade charger which will jump start a vehicle. However, using my extremely good cables and another vehicle gets the job done much better. This will be a good thread to follow . . .

Well, most of the home grade chargers i saw yesterday when i was looking had 75-100 amp starting functions, the commercial ones i saw at sears had more like 120 amps.... i think thats better than most cars and light trucks put out from the alternator. I could be wrong. I was just recharging my battery at 10amps between attempts though.

still thinking about my starter.

Ouch, Deja vue.
 

"1985 300SD Sady" had the same issue; he was using a ten amp charger, waste of time.
The minimum you need is a fifty amp charger, a one hundred twenty amp charger would be better.

A ten amp charger will take twenty four hours to top off your battery.

"PM", 1985 300SD Sady, if you have any doubt.

A diesel has got to spin pretty fast or it won't start. If yours is going "whump, whump, whump" it's a cinch you have a "tired" starter (meaning the internal resistance is way too high).

The "start" function won't do anything for you -- that starter normally draws 900 A or so on a cold engine, any extra 100 won't do anything for you at all. When they get "tired", the starter can draw upwards of 2000 A! Battery goes flat VERY fast.

Put a paint spot on a fan blade and have someone crank it while you attempt to count how fast the spot goes past. Engine MUST turn at least 100 rpm, so you shouldn't able say "1001" before it goes past again.

My brother's 300D quite starting cold last winter (complete engine rebuild a couple years ago, should start instantly). Cranked REALLY slow, simply refused to start until it warmed up. Finally got him go buy a rebuild (by Bosch) starter, and the difference is simply amazing. Still takes a full minute stone cold on the glow plugs (series), but it starts instantly then.

Peter

its not that bad.
 

I'm patient, and i find that the 10amp is doing ok. I don't plan on charging so many batteries that i have to hurry, this is an occasional, not critical tool. but faster is nicer, i'm with you on that. And i'm still not starting after a full, overnight charge.

I'm using this to recharge the battery over time, not assist with starting!

Can you hear the engine start to slow down after a couple of trys on the starter? If so, I would suggest trying to put a higher Amp charger on the battery while cranking.

This is a problem that I ran into. I bought a new battery (you said you did also) and a charger with a 50Amp setting. Whenever my car doesnt start the first time, I run and get the charger without hesitation.

?block heater?
 

Do you have a block heater installed in your engine?

I'm fuzzy on the exact location of your connection, but look for a male plug
some where on the passenger side of the FRONT after you open the hood.

That would eliminate ,at least for testing, the glow plug concerns.

Diesels are funny about "jump starting" . I've started compression engines
with "BAD" starters by OVER VOLTAGE/OVER AMPERAGE(the difference
between two "Booster" batteries in sequence/parallell)

On the car, an AMP draw measurement as the starter is turning,will tell you
all you need to know. (But , most of us lack the "Hall Effect" clamp to
enable our multimeters to make the measurment [cost] ).

I looked for a block heater thinking it might have one, but couldn't find anything. Should i expect one?

Can you elaborate? Was the second battery more useful in parallel or series? I guess traditional "jump starting" is adding another battery in parallel. Did you have success with "jump starting" in series, using 24v?

Melt down the starter and electrical system
 

under one second with 24V current. :eek: :(

Attached is a drawing of the only SAFE way to add a second battery for more cranking power.
The flaws are added weight and if one goes bad, it can scrap both batteries and the alternator.

Well, i know it runs once it gets started, so i think i'll wait for my new starter to come in the mail rather than mess with 24v. thanks for the help and i'll let y'all know what happens.

While cranking, are you holding the accelerator pedal to the floor? This helps with a cold engine, as the extra fuel assists in starting.

Have you tried having the car towed to start it?
MB Automatics in the W123 series can be tow started.
With the key in the ignition (Acc position should release the steering lock) and the car in neutral, have the car towed to 20MPH. turn switch to the ON position so that glowplugs operate.
When glow lamp goes off, slip transmission into "L" and the engine will turn over.
If it starts easily, the problem is in the starter/barttery. If hard to start, there may be problems with air in fuel, injection timing, fuel quality or other problem.

I am holding accelarator down when cranking.

I have not tried tow starting it. I do know that it runs well from test drive and driving it 60+ miles (and 2000 verticle feet) home on I-25 a week ago. I guess i might try tow starting it to drive it to my friend's shop for new starter install; it would be nice to know that it still runs.

I use my Diesel truck...................that will supply me almost 2,000 cca Two Optima batteries in parrallel. more jiuce than any jump box will give me.

New Starter In!
 

now it starts like a champ. Thanks for the help! I'm sure I'll have lots more questions, but I'm going for a drive right now!

bump
 

Thanks everyone!

You are welcome...
 

Nice to see another happy Mercedes Benz Diesel owner. :)
You must have a something or other eating grin, stretching from here to there right now. :D :D

i guess i'll have to ride on this thread right now..

just had the news arrive.. my alt and starter have gone south at the same time!.. arrgh!.. just when i was saving up for somethign i've really wanted to buy this happens.. :( i guess i'll have to postpone buying that gift for me..:(

question... would a 70AMP rated alternator work fine with my car? my old alternator was rated at 80AMP.. but whenever we test it if it were charging.. it is just holding 12V.. it doesnt even jump up when revved hard to 14V... i've manage to start the car from time to tme..but since both alt and starter is going south.. it is really hard to do that..

You need the 80 AMP alternator.
 

Replace the voltage regulator, if it looks like the attached picture, that is what died, not the alternator. :)

1979 Mercedes Benz 300TD
Part: Voltage Regulator
http://www.pelicanparts.com/catalog/SuperCat/3386/MBZ_3386_ELCHRG_pg1.htm#item5

What makes you think the starter is bad??? :confused:

thanks for the info whunter...

we've already replaced the IC. but still no reading from the machine that measures the charging (dont know the name.. but the battery shops have them).. i went back and forth from the shop to the battery shop.. everytime they did somethign to the alternator to check if there was a change.. nothing.. so no recourse but to replace the alternator completely.. seems like the alternator is really dying...

or is it possible that one has a healthy alternator but it just wont register on the machine?.. if so.. what then could be the culprit?

right now.. i'm afraid to even think of what i'll be buying over the weekend.. a bnew 80amp bosch alternator here would cost around 15,000 pesos.. roughly around $250.. a reconditioned one.. around half that.... still not a cheap thing to fix.. especially with the death of the starter too....

My trouble turned out to be the connector to the
 

alternator. I cured it by tightening up and cleaning the female connectors in the socket.

that's actually what was wrong with it BEFORE.. ehehe.. when we got the connectors fixed.. all hell broke loose.. .any testing on the charging didnt show anything more than 12v. IC replaced, 3 wires inside were resoldered as they were "a little" loose, the big thing inside with the wires (dont know what to call this) have been replaced back in july... in effect my alternator is already a frankenstein.. no more original part in it. except for the casing and the pulley.. ehheh

could i have fried my alternator due to that loose wire? i read in another thread you can fry your alternator with a bad positive wiring.

Yes
 

sounds like the windings are shot. :(
Have you tried www.ebay.com for a good used one?

thanks for the reply.. i'm about to replace the alternator tomorrow for a surplus one... hopefully things get back to working order again.. and i'll check out the postive connection of the alternator very well as well as the negative grounding... i dont want to fry another alternator.. if only i could afford a bnew one...

i'm still hoping by tomorrow my contacts would've found an 80AMP.. otherwise.. i'll have to use th 70amp that is sitting by idly in one of my friend's shop...:(

My local parts house only show AC Delco and Orange County Alternator (OCA) remans. But when I can get it at less than half the cost of a new bosch (about $100), it's worth it.

Don't count on cheap starter working for long
 

My original starter went bad and would no long run when the starter key was turned. Jumping it wound up shortening the unit out with smoke and the classic electrical burn sent in the air. Since I didn't have a replacement starter I purchased one at a local discount automotive store. Once installed it worked fine for 3 weeks.:mad: I turned the key to start the car to get home from work. All dash lights where working and even the headlights. This indicated that the battery at least still had power. How could this be. It starter motor stated Bosch on the side and even had the same name on the solenoid. Jumping across the solenoid with a screw driver only resulted in a bunch of sparks.
Luckily, by this time I received my original starter back from the rebuilding shop. I did an emergency repair in a crowded parking lot, jacked the car up, put a jack stand underneath the car and replaced the starter. The car is a 240D with a 616 engine, so it was somewhat easier than a 300D. Once replaced, the car started right up and I drove home.
Moral of story, don't trust discount starters in diesel cars. These have more compression which needs more power to spin these engines over. Plus since they draw more power, this results in more heat which can melt things in a starter motor. So I will be caring around a jackstand, a good starter motor and the tools necessary to install it in the trunk for a few months

Glad you got it straightened out, those parts, some with a lifetime warranty, simply don't last and you spend a lifetime replacing them!