Runs Great, won't start? - PeachParts Mercedes-Benz Forum

Sloppyjoec · #1 07-01-2011, 09:57 PM

my 1975 w115 240D with manual glow plugs and pneumatic Governor would not start without a fight and would run like a sweetheart.

Fought this for years, new glow plugs, fresh fuel lines, filters, you name it, in the meantime it only got worse, until it wouldn't start for good.

Just about sold it for parts, the first guy on the phone talked me into another look, IT WAS THE START/Stop cable with too much play in it, started a minute ago a lot better than it has in awhile.

My wife is gonna kill someone.

kerry · #2 07-01-2011, 10:39 PM

I was going to suggest investigating a problem with the stop mechanism.

Sloppyjoec · #3 07-06-2011, 12:34 PM

Went to take it to work today and no start, just like before. I tried to hold the lever aganst the start pos. while my wife cranked it an dno signs of life, back to the drawing board

NickCox · #4 07-20-2011, 03:36 PM

I have a 1975 240d. It has been slowing getting harder to start (long time cranking) for the last couple of weeks. It has the same symptoms as the starting post.

Right now the car won't start.
I've bleed the fuel system without benefit. New fuel filters about a month ago.

Engine has good compression, and the glow plugs work (new) It seems like it's not getting fuel.

Any input would be appreciated. I kind of need this car to be running soon.

kerry · #5 07-20-2011, 03:38 PM

Quote:

Originally Posted by NickCox

I have a 1975 240d. It has been slowing getting harder to start (long time cranking) for the last couple of weeks. It has the same symptoms as the starting post.

Right now the car won't start.
I've bleed the fuel system without benefit. New fuel filters about a month ago.

Engine has good compression, and the glow plugs work (new) It seems like it's not getting fuel.

Any input would be appreciated. I kind of need this car to be running soon.

Feed it off a soda bottle filled with diesel in the engine compartment. If it runs ok then, youknow the problem is upstream in the fuel system.

NickCox · #6 07-20-2011, 04:01 PM

Thanks kerry.

i believe the fuel going to the pump is fine. I have a half a tank of fuel. I already drove the car 200 miles on the same fuel without issue. The pump is getting fuel. The pre-filter is clean.

boneheaddoctor · #7 07-20-2011, 04:13 PM

When was the last time you checked the valves? They might have tightened up recently enough to cause a compression drop.

NickCox · #8 07-20-2011, 04:16 PM

I adj. the valves when i bought the car, about three months ago.

Diesel911 · #9 07-20-2011, 04:21 PM

Quote:

Originally Posted by NickCox

Thanks kerry.

i believe the fuel going to the pump is fine. I have a half a tank of fuel. I already drove the car 200 miles on the same fuel without issue. The pump is getting fuel. The pre-filter is clean.

Kerry's suggestion was a good one because troubleshooting is often a process of elimination.
The whole idea of it is to take the "I believe" type guess work out of the equation.

If you did what Kerry suggested and it ran OK like that it would tell you a lot.
If you still had trouble starting after doing what Kerry suggested that would also tell you something.

On this forum and other Mercedes Forums the Diesels made around your time seem to be having starting problems. I am thinking that the Fuel Supply/Lift Pumps or the Fuel Pressure Relief/Overflow valves need some fixing after all of these years.

Replacing the little Valves inside of the Fuel Supply Pump and the single O-ring that goes in it yourself is in the $15-$20 range.
Or if you have the Mercedes Service Manual and a set up to do so you could check the Out Put pressure on the Fuel Supply Pump.

piccolovic · #10 07-20-2011, 05:02 PM

Run a fuel system cleaner through, that will go through the IP and injectors. Hopefully you can get it started then. Do you have any leaking from the return hoses?

whunter · #11 07-20-2011, 05:03 PM

If the timing device and/or springs are weak/worn out = you will be trying to start with massive overfueling = flooding.

Press/hold the mechanical stop lever, have an assistant cycle the glow plugs then crank the engine.

If it starts and runs = odds are 70% the timing device and/or springs are weak/worn out

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NickCox · #12 07-20-2011, 10:32 PM

Tried a few things..

Held the mech. stop lever forward, toward the front of car = Cranks, but without effort to start

Then I moved the mech. lever around, and left it disconnected from cable. (pointing straight down) = Cranked car, after 5 seconds of spinning, engine sputters a little more, and fired right up. Car runs and drives fine.

An hour later I try to start to car again, without success (10 seconds of cranking) Cable connected from gorilla knob to mechical stop lever also.

Thanks for all input, not sure what to think

NickCox · #13 07-27-2011, 04:02 PM

After this past week of fighting the ol' 240d, I'm looking for much needed advice.

I don't believe the mechanical stop level is the problem, at all.

Now here is the newest problem to boot. Good fuel leak coming from the injector pump. I noticed it two days ago. When the car is idling there is at least a drip of fuel every 5 seconds to the ground. The top delivery valves are not leaking. Injectors leak slightly from return lines, but not anywhere close to the volume of fuel leaking to ground. I'm still having starting issues whether it be hot or cold. After shutting down the engine, the leaks seems to stop or really slow down.

I'm guessing the starting issue has to do with losing prime in the injector pump? I've noticed in the past a little diesel on the ground after driving, but just assumed it was from injector return lines leaking. Was that the start of this leak? Now its really bad.

Leaking lift pump? I've tried to find the leak today, but its a mess down there!

Hope someone has ideas

Thanks in advance

piccolovic · #14 07-27-2011, 04:21 PM

OK . . . I had the same exact problem on the same exact engine . . . before you look at lift pumps, IP rebuilds, etc.:

1. start with fixing the obvious, and usually the cheapeast!!! Before you go past "GO," replace all of your return lines and bleed the system. You would be amazed at how much is actually leaking and may be the entire cause of the problem. The old return lines get eaten up by the newer diesel fuel, and have to eventually be replaced by the new stuff that is reformulated. This is where my problems stopped on my 190D.

2. However, on my 240D, it was less of a problem, but not the entire fix, and I had to go to step 2. If you still have a leak, look to see if there is pooling under the injectors . . . if so, time to remove your injectors, put on a table-mounted vice grip and snug them up, replacing any o-rings or snap rings that may also be required. If there is no pooling from the injectors, then go on to step 3, which should also be looked at immediately.

3. Check every clamp, hose, and tubing go make sure there isn't any leaking from connections to and from aux fuel pump/primer pump, pre-filter, clear in-line filter, etc. Trace the entire fuel path under the hood of the car. Make sure the tubing isn't leaking where it's connected to the IP or Injectors, and anywhere else they connect. After you have eliminated all that, and only after all of the has been replaced and eliminated as a source, should you start looking at pump, or IP, and if it is either, make sure it's not simple mounting gasket, first. Never mess with the IP adjustments unless it is last resort!!! and then only, if you have a backup plan!!!

barry123400 · #15 07-27-2011, 04:24 PM

Quote:

Originally Posted by Sloppyjoec

Went to take it to work today and no start, just like before. I tried to hold the lever aganst the start pos. while my wife cranked it an dno signs of life, back to the drawing board

Well I assume you have checked the valve clearances. If so it is time for a compression check. Also does the starter sound like it is turning the engine over quick enough.

Try using the primer pump before any of the above until you hear the relief valve squeek just before attempting to start. Could be as simple as the fuel draining back. Or try having someone pump it during the attempt to start as well.

I have to assume that you monitored the actual voltage at the glow plugs with the key or whatever in the glow position. New plugs alone are no gaurantee the system is working.

For example as well a shorted glow plug down the line could take a glowplug offline and there are a lot of diesels that just about refuse to start even with just one plug offline.