1978 240d won't start, need new angle - PeachParts Mercedes-Benz Forum

trafalgor · #1 12-07-2014, 05:07 PM

About the car: 1978 240d, had for approx. 6 months. I have all the maintenance/service records and note that the compression has been low since about 18 years ago (96): #1:220, #2=220, #3=220, #4=250.. Have not tested since. It has only ~165k (odo works). So, I realize this one is always probably going to be on the edge of having enough compression to start. In its prime it had VERY low power, though could go ~70 on flat freeways, with enough time.

Problem/symptoms: won't start. It had some difficulty starting on recent colder mornings, needed trickle charge at battery after long attempts, and then finally reached the point where it has been for about 1 month. Cranks, but won't start. Using 2 ga. jumpers from my truck, no luck. Starter/battery seems tired after maybe 2-3 20 sec cranking attempts, even with jump. Starter is new within one year. Noticed oil was very low, but not dry (seems to be burning a qt every several hundred miles).

What I have done/checked:

--changed to synthetic oil, replaced filter
--new fuel filters (have not replaced tank) 2nd time I've changed in 6 mos. I also ran purge in separate tank twice to clean injectors before this no start problem began. It did seem to improve compression.
--bled hard lines, primed/filled secondary and primary.
--no leaks at pump
--cracked nuts at injectors and confirm fuel delivery while cranking
--vacume checks out, fuel shutoff not stuck
--tricked tablespoon of oil into each cylinder to seal, in case diesel dried it out and lower temps shrank up the seals.
--checked GPs (pulled 2, checked rest for voltage/draw)- all good. Relay good. oddly, resistance reads zero at all except one of them. Not sure why. Two of those with 0 ohms were pulled however, and are working fine. All of them measure approx 10v when drawing current, and all are getting 12V.
--running block heater before attempts
--Adjusted choke which had loosened, now tight.
--Turned crankshaft manually at PS pump, seems okay.
--Battery voltage okay, but seems a little sensitive to my attempts to start. I trickle charge it over night with 1.5Amps and charger says battery is good and charged after a day or so. Car cranks and sounds like its going to go the first attempt or two, but then... maybe 2 cranks per second. Slower and slower. Voltage is like 12.8 before starting.
--checked valves, which seemed a hair loose, if anything. None were too tight. Did not change (lack bent wrenches).
--won't even start with WD-40 sprayed into intake while the wife cranks.
--alternator belt seems loose, so I'll tighten.

This car is definitely hanging onto the low side of life, but the original owner (30yrs) took good care, and it suits us fine. The temp is like 40 here, so it isn't criminally low. Could it be solenoid, even though it is only a 1+ years old? Is the compression so low that it just won't start in the cold? Nozzles? What else should I try, what else can I check? Keep in mind that I'm definitely a novice, and low on time. Car is marooned in driveway.

I really appreciate any ideas, expertise. I've probably learned everything I know about maintaining this vehicle from this forum.

leathermang · #2 12-07-2014, 05:34 PM

Ok... from your description I would suggest you be sure you have a really strong battery AND really clean the connections .... to the block also....
That low on compression means you have no leeway in terms of cranking speed...
Try three seconds while cranking of starter spray.... into the intake tube ....

FSM says not to use the PS nut to turn the engine... use the crank nut.... reasons in archives...

How did you install that oil into the cylinder ?
You have the old style glow plugs I assume.....

Your engine may just be plumb worn out..... oil usage, lack of compression 18 years ago, most things checking out fine and using a block heater..... you need to do a compression check...

t walgamuth · #3 12-07-2014, 06:01 PM

According to my old Chilton's repair manual you need 220 psi cold for reliable cold starts. I'd check all the basics....including the grounding. Poor ground will mimic other more serious problems. Check for clean ness the ground strap from battery to chassis and the engine to chassis strap. I have added an auxiliary ground from the starter to the chassis before....from starter bolt.

And of course check glow plug function.

Skippy · #4 12-07-2014, 08:36 PM

Loop plugs or pencil plugs? Your year I think would have come with the loop style but someone may have upgraded to pencil at some point. The loop system is more complicated since the plugs are wired in series with opportunities to hook them up wrong.

What is this choke of which you speak?

TnBob · #5 12-08-2014, 01:51 AM

If you have 2 GP's that are ohm reading 0, you can stop hunting as that will surely cause a no start.

Even with an HF cheepie DVM you should be reading under 10 ohms but should NOT be reading 0 !

http://www.ngk-dpower.com/index.php?id=31&L=2

moon161 · #6 12-08-2014, 03:28 AM

A motor swap isn't that hard a job. It's not that easy either, but neither is throwing work at an engine that was marginal 20 years ago. If the gloplugs get hot and the injectors get fuel, my guess is wore out.

Look up the MMO soak, and try that if you're inclined.

I'd look on craigslist for a engine or replacement 240D if affordable.

Mrecedes 240D 1982

toomany MBZ · #7 12-09-2014, 08:33 AM

Agree with checking the ground connections and have a strong battery.

Also agree with TnBob, a 0 reading indicates a problem, should have a low, but observable reading.

If you have the loop, series style glow plugs, if one fails, none will work. Just like the old style Christmas lights.

funola · #8 12-09-2014, 10:56 AM

Quote:

Originally Posted by trafalgor

.........
--Battery voltage okay, but seems a little sensitive to my attempts to start. I trickle charge it over night with 1.5Amps and charger says battery is good and charged after a day or so. Car cranks and sounds like its going to go the first attempt or two, but then... maybe 2 cranks per second. Slower and slower. Voltage is like 12.8 before starting.
...............

This is a major issue. 2 cranks per second is reeaally slow and will not start the engine. Trickle charging overnight with 1.5 A will not bring a low battery to up full charge. Try charging it with a charger capable of 10A overnight and try again. Bring the (fully charged) battery to Autozone for a load test to eliminate your battery as a problem. If good, check and clean all battery cable connections including ground strap. You could also have a weak/ bad starter. A healthy starter/ battery should crank above 150 RPM.

trafalgor · #9 12-09-2014, 09:38 PM

Thanks for all of the responses. Though it makes sense, I hadn't realized how fragile my cold starting could be with a low compression 240d, and thought that my battery registered to spec for starts.

Responses to questions:

RE: SKIPPY, etc:

The GP's are Bosch pencil plugs from one year ago. I pulled 1 and 4 (easiest) and got full glow with jumper cables. I checked all for power with a 12v check light and got a light. I checked all for 10V under load and got ~10v (I read thats a normal MM reading for GP's recieving 12V.) With ohm meter, I got 0 from all except 3, with read .6, to spec. Twice. My knowledge of electrical matters may be lousy, but I assumed that I should check for resistance without power. Correct? What accounts for how 1 and 4 measure 0 ohms resistance at the plug and both are recieving/drawing power and producing a healthy glow?

RE:LEATHERMANG

The oil in the cylinders was installed by pulling valve cover and air intake cover, rotating intake valves to "open", and pumping in about 1 tablespoon of oil into each cylinder, then rotating crankshaft a couple revolutions at PS pump. I note from responses that this method of rotation may be incorrect.

As for battery issues: the battery had died twice in starting attempts the weeks before the car finally refused to start. I feel silly now, reading all of your responses and realizing that it is likely an electrical issue, but, I think you guys are on to the cause of the no start. I haven't checked the grounds, and just assumed, maybe naively, that 12.9V is appropriate to start. My VM is a Klein tool and not a HF, TbBob, so I don't think it is a meter error.

I'll check out the battery. Many thanks, y'all! If anyone thinks of something, please, post some more... thanks again.

leathermang · #10 12-09-2014, 09:49 PM

Ok... looks like you are on your way to it starting IF it can start.... let us know how it goes...

Lucas · #11 12-09-2014, 11:08 PM

Before spending money, I would clean all connections and have the battery charged at the auto spot. Unless you spent big bucks on a charger they do it better and have better testing equipment as well.

I would run a few glow cycles and tow it with something dropping the clutch in second gear until it runs. I would let it turn the motor over a good 5-10 seconds at a time. Hence, you need a tractor or big truck to tow it.

I would let it run to full temp or longer and then check compression. If the battery wasnt tip top I would hook jump cables on from a running vehicle.

And see if it's worth doing anything with.

Then buy glow, battery, check alternator, etc.

Maybe a MMO soak. Especially if it sat for a bit. And you can put oil in through an injector hole. Easier if a valve is open.

I'll warn you, my neck is red.

moon161 · #12 12-09-2014, 11:40 PM

Settle it with a tow start. Tow at 5-10 MPH, gas pedal on the floor, put it in first and engage the clutch.

If you haven't already, loosen the nuts on the injector lines and to make sure each injector is getting fuel.

gastropodus · #13 12-10-2014, 01:13 AM

I see you're in Portland: I'd be happy to come over this weekend and look at with you. My money is on the battery being weak, based on your description of the RPM. If anything, with poor compression the starter ought to spin it faster, although I don't know if that is a measurable effect! Due to my recent starter issues, I also have a brand new battery we could swap in (don't ask me why), and good electrical tools for measuring current, voltage, etc.

Kurt

Lucas · #14 12-10-2014, 10:25 AM

Quote:

Originally Posted by moon161

Settle it with a tow start. Tow at 5-10 MPH, gas pedal on the floor, put it in first and engage the clutch.

If you haven't already, loosen the nuts on the injector lines and to make sure each injector is getting fuel.

1st may be correct. I was thinking about the compression. With 400 lbs it will drag the tires in first. But then again I'm on dirt.

psaboic · #15 12-10-2014, 10:45 AM

I would pull ALL the glow plugs and make sure they glow properly with jumper cables ( I use a battery jump box to test mine). I had a no-start problem that turned out to be glow plugs. They all tested fine for voltage and resistance, but when I checked them out with a jump box only two glowed at the tip while two glowed in the center of the plug. Of course glowing in the center of the plug is not going to help a damn bit as that part of the plug is buried in the head. I changed out those two funky plugs and she started right up.....just my .02