'77 240D rotates but won't start - PeachParts Mercedes-Benz Forum

glenn1179 · #1 10-23-2005, 11:56 PM

Newbie diesel mechanic here. I acquired a '77 240D that ran when we drove it on the trailer. It had been sitting for about 5 years before that. I had it running when I got the car home, but now it rotates and won't start. The serial glow plugs work, which is evident by the glowing "W" wires in a dark shop. I changed fuel filters (primary & secondary) and replaced the fuel in
the tank with fresh stuff. None of which looked bad, the fuel was all
clear and their was only a little black in the primary filter. I took
the fuel return line off (where the rubber line connects with the steel line that returns to the tank) and pumped on the hand pump until I pumped
about a pint of fuel through with no air bubbles after the filter changes. No leaks present anywhere. I had a buddy come and double check my work on the valve adjustment I had done and it all looked good. Cleaned the electrical connections to the starter and grounding straps. I am using a deep cycle marine battery and even jumping that with another vehicle to make sure I have plenty of juice.

I also noticed there is no more white smoke coming from the exhaust
when I crank it over. If I crack an injector line to make sure there
is fuel present there, how much fuel should I expect to see flowing out? (I regret to say I even tried squirting some diesel into the intake to get the car to start, but it had no effect.)

Still no go, so I plugged in the block heater for a couple hours and then pushed the thing down a couple big hills by my house. This is an auto tranny, but I was told I could still roll start it. Turned the key to position 2 and rolled it up to 30 mph. I put it in second ....but nothing happened. The car continued to roll as if it was in neutral. What am I missing here???

I am working on locating a compression tester. What other chain car
part stores besides AutoZone do a tool rental program for me to check
with? (Autozone told me they don't have a diesel compression tester.)

Sorry for the long post, but I wanted to be complete. Any advice is much appreciated.

Glenn

t walgamuth · #2 10-24-2005, 12:53 AM

like you have air in your fuel system. when cracking the lines you should get surges of fuel, not huge flow but not bubbles. if your glow plugs work you should be able to start it on wd 40 sprayed directly into the intake with the air filter off.

it ran before so it should run now unless you have the valves adjusted so that they aren't closing. if it cranks over very fast with no bumping that may be the case.

rolling down a hill to start an automatic is not likely to work. it will with a stick though. (unless youlive on a mountain)

good luck.

tom w

glenn1179 · #3 10-24-2005, 09:17 AM

Nope, no mountains in Wisconsin. I tried cracking an injector line and only got a little moist area around the top of the injector. I don't think that qualifies as "surges of fuel". What should I expect to see, a tablespoon, so much I would need a container to catch or make a mess? If I have bleed the air out of the lines, should I just crack all the injectors and go to town on the hand pump until I see fuel at each one?

Thanks,
Glenn

glenn1179 · #4 10-24-2005, 02:15 PM

I made sure I was getting fuel at 4 injectors during my lunch break. I also noticed that even with a fresh charge on the deep cycle marine battery and jumping it from another vehicle the starter seems slower than a normal gas engine. Is this normal or is the starter possibly shot? (Also, yes, the motor, does, "bump," rather than just rotate rapidly at a constant rate, so the valves should be closing to make compression.)

Thanks,
Glenn

#5 10-24-2005, 02:28 PM

Why are you so convinced that the problem is not glow plugs? To make sure they are working, you need to see about 3 volts across EACH glow plug. The glow plugs can short to ground through crud buildup. In that case you will not see the voltage evenly dropped across each plug.

If voltage across all the plugs is about the same, then it is indeed time to do a compression test.

Good luck,

glenn1179 · #6 10-24-2005, 03:48 PM

I just assumed that since the GP's "W" wires were glowing red hot in a dark shop that the circuit was good.

Good point Larry about them possibly grounding out. I will test that out tonight.

Thanks,
Glenn

brokentroy · #7 10-24-2005, 03:54 PM

I just went through a similar situation with my 87 300d. wouldn't start. tried roll starting, but it would not turn over. Not sure if yours has a catalytic converter, but mine did and it was blocked. I took it off and put a straight pipe on and it runs like new. if you don't have a cat, it may be some other kind of ehaust blockage. Just a thought.

glenn1179 · #8 10-25-2005, 09:24 AM

Well I started to work on the car last night and lost power in the garage. I guess that was a sign to take the night off.

Will have to update later with the GP test. Also, where is there a good explanation of a serial GP test that uses a key to activate. I have been searching and the threads always seem to go off on a tangent about gorilla knobs or parallel GP's.

Thanks,
Glenn

mike2005 · #9 10-25-2005, 09:51 AM

Deep Cycle batteries not recommended for cold cranking of an engine. However, with second jump starting battery, juice is not the problem. Also doubt that starter is causing the "no start" problem. It does not take high speed turnover to start a diesel. Repeated cranking w/o time significant pauses for starter heat dissipation will ultimately buen up the starter.

1. Confirm filter connections are tight, air may be entering fuel system.
2. Bleed each injector line and confirm delivery of fuel both w/ hand pump and system pump. If fuel delivery is confirmed, it is likely that the valves were improperly adjusted preventing adequate compression.

Running before alterations (filters, adjustments) but not afterwards points to problem being caused by alterations.

123 300D driver · #10 10-25-2005, 02:48 PM

Glenn1179,

I had a similar no-start problem with my 79 300D, years ago. However when I plugged the block heater in for a couple of hours on a warm day, it started.

You said you tried a block heater and then tried to push-start the car. Did you also try to crank the engine, and was it on a warm day?

I eventually switched over from series to parallel plugs.

glenn1179 · #11 10-25-2005, 03:13 PM

Normally, I would agree that if it would start before you worked on it and then it didn't start after, it must have been done wrong, but this old wreck never started easily under my ownership and required ether to get going before. I did the valve adjustment to hopefully help. I will go back and triple check that they aren't out of spec.

I am thinking of the conversion to parallel plugs, but may just stick new serial ones in until I can verify that this $350 ride is worth the $100 investment. If the power doesn't go out on me tonight, I will check and see if all of my glow plugs work for sure.

I had tried cranking after the block heater heated everything, but no success. I am running out of warm days.

SD300 · #12 10-25-2005, 03:33 PM

Check the compression anyways, for diesel u need compr and fuel.

Or bleed the air not enough, or not enough diesel getting up to the injectors.
Good luck.

ZackaryMac · #13 10-25-2005, 10:16 PM

Quote:

Originally Posted by mike2005

It does not take high speed turnover to start a diesel.

You will also never start a cold diesel with a near-dead battery. Diesels do indeed require strong cranking speeds to build up enough heat from compression to start quickly. I've seen gas engines barely turn over, then light up, but not a diesel.

unkl300d · #14 10-26-2005, 12:04 AM

anybody mention valve adjustment?
my 240D wouldn't start. after all the diagnostics, turned out to be valve adjustment.

D.

glenn1179 · #15 10-26-2005, 12:17 AM

Well the good news is I had perfectly functioning glow plugs. The bad news is I broke one to find that out. I did a resistance test and all were at .7 or .8 ohms, and my cheap meter registers .3 ohms by touching just the leads. I decided I should be extra sure and pull them and connect them to a 6 volt battery charger. They all glowed, but in the process of removal on of the GP's got a broken stud due to a stubborn nut. I did notice that they were a pain to get out because it was all the way unthreaded but it seemed like the carbon buildup had a vacuum seal on it. Atleast I thought it was carbon build up. Is there supposed to be a lip that can be felt in the block shortly after the GP threading stops and the taper of the plug changes? If the answer is yes, then I guess all is well.

Well since I had the GP's out I dug out the old remote starter and gave the engine a wirl. Noticeably different tone due to lack of compression. I also noticed that diesel fuel was misting out of all the GP holes, so I am getting fuel to the cylinders.

This leaves the fuel is not arriving at the right time, air cannot get in (which it should with the air cleaner open) or out (maybe the mice packed the exhaust full), not enough compression, or the starter is just a little too tired to get the job done. Anything I am missing?

I am working on getting a compression tester yet. The starter that was in the trunk of the car when I bought it tested good at autozone, so maybe I will slap that on. I will have to search and find info on how to check IP timing.

Oh, and order a new GP to replace the good one I broke. Maybe I could skip all this wrench turning and get it started on a bunch of wd-40 now that I can run the starter with the remote and spray at the same time. Then I could just try old Italian tune up.

Woah, I wrote a novel....any other suggestions appreciated.

Glenn