Cold Morning Problems - PeachParts Mercedes-Benz Forum

Rmcfarland · #1 10-24-2007, 01:44 PM

Well, with the cold season all up on us, it's time for the ol' MB Diesel to start complaining.

Anyway, it got down to about 29-30 F here Monday night. My 240 refused to start that morning at 30 F. What the heck. It's been starting ok at 40, and last winter I didn't worry unless it was under 20F. But that morning, I had nothing. Barely tried to catch at all, glowed for over a minute. Hit once or twice on a cylinder. Tried several times but the battery was weakening.

Charged the battery for an hour or so about noon (45-50F) and tried again. Fired up pretty easy, little hesitation and ALOT of grey/white smoke (probably flooded her in the morning?)

So, here's my questions.
Would summer fuel (no additives) have thickening problems at 30F? I wouldn't think so. But, my clear primary filter was pretty full of crud, so I thought any thickening might hurt it. So, I replaced it. Then, I went out for a drive, got it warmed up and redlined it a couple of times. Blew out a nice cloud of black smoke the first time I did that. I also ran a can of seafoam through it (diesel-purge style, cant get purge locally-also never done a purge). Seafoam didn't seem to do anything.

I also tightened the glowplug connectors and put some powerservice winter additive in the diesel tank, in case it was thickening in the cold.

Here is a list of other info that may help.
-still have (probably pretty old) series glow plugs.
-I drive lots of short trips around town. (carbon buildup+charging?)
-Haven't checked valves in over a year. (on the list-of-crap-to-do)
-Running 15w-40 dino. (rotella-T)
-fairly new big battery. (800-850CCA, don't remember. interstate, i think)

I probably just answered my own question more or less. Do all this stuff. But, it's been starting fine, and this is only like 10 degrees less. Also, how much can that carbon buildup hurt. Can it make cylinders lose appreciable compression? And, lastly, what would the experienced recommend for a car that burns a healthy bit of oil run in the winter? I hate to be burning up lots of that 'spensive synthetic, but a thinner oil will burn more!

Thanks all for the help. I would imagine others are starting the winter worry over their diesels too. Good luck out there!

MattBelliveau · #2 10-24-2007, 01:54 PM

If you aren't starting in the 30's, you should deffinately look at replacing GP's, and I would recommend updating to the newer system. I would also check your valves, and chainge to a lighter oil, but I don't think these would be your current problems. Also check your fuel filters, but my money would be on the GP's.

Old300D · #3 10-24-2007, 02:03 PM

Second the glow plug thing, especially if the firing is uneven at first. You may just have a weak alternator not fully charging the battery. Until I recently replaced the regulator module, my car was having trouble turning over in the mid 30'sF.

Rmcfarland · #4 10-26-2007, 01:39 PM

1979 240D. Ok, so here's the skinny. It has been 28-40 degrees overnight, and I've been starting. But sometimes barely. So, I think I have it narrowed down some; the car seems to be cranking slow. I would say 3 cylinder hits a second or so, a whump-whump-whump when cranking. So I measured the batt. voltage when I got home last night. 13v with nothing on, dropped to 12.6 when the headlights were turned on. This is with engine OFF. So, I put a charger on my ~1.5 year old interstate battery overnight, and it still cranked about the same this morning. Kind of a rough start, but it went ok. 15w40 Rotella T in the crankcase.

This sounds like starter to me, maybe? So, I will take it to the Autozone today and have them measure cranking amps out on my battery, and amp draw on the starter (I believe they can do this). What should the starter draw when cranking? And, what is a good batt voltage during cranking?
Thanks all for any input.

Also, do most of the 240D's out there smoke a little until the engine is up to temp? (and let out a nice belch when they start)

Rmcfarland · #5 10-26-2007, 06:51 PM

I took the car to autozone, and here is my (measured) readings.

Battery: 13.23V, 701 CCA at 62 farenheit.

Starter (cranking): 12.06V, 56.0A

Charging system: 14.04V NO LOAD, and 13.83V LOADED (blower and high beams on)
21mV ripple

Drain test:
0.00A draw

So, my system checked out OK. Is 56A a low draw on the starter? Any thoughts, or where to begin?

TMAllison · #6 10-26-2007, 06:55 PM

3rd vote for GP's.

Zerohour3k · #7 11-06-2007, 07:36 PM

Similar problem with my 83' 300D. It gets down to about 38 some nights, which isn't too cold. Here's the weird thing, the car starts right up without any issues. After I glow it, she fires right up.. and proceeds to run like garbage. The engine shakes, idle is incredibly poor, and giving it some gas has very little effect. Exhaust blows lots of white smoke (with what looks like a blueish tinge, but I could be wrong.. since the engine doesn't burn oil that I know of.).

Once the car warms up, she idles like a champ, and continues to do so until the engine gets "cold" again. I stopped it from stalling out by replacing the idle speed governor bolt with the "updated" gold one, but that didnt' seem to fix the rough idle. Glow plug issue?

Thanks!

calebc3 · #8 11-06-2007, 09:25 PM

thesst - check connections including grounds and main ground
Zerohour3k - check glow plugs

BobK · #9 11-06-2007, 10:05 PM

Slow cranking is a good way to not start in winter. Only a couple of factors here. 15w40 could be a bit thick for 30ish temps. 5w40 Mobil1 might help. 50 amps for starter? Is that on a bench or turning the motor over? Sounds way low for spinning a diesel engine. Like they said above, check the condition of the cables/connections from the battery to the starter...hot and ground. Battery should not drop below maybe 10.5 volts when cranking. Even higher voltage is a lot better. If battery and cables are good, starter is next. If you can get one cheap from a boneyard, do it.
If the engine starts but seems to hit and miss with the series style plugs, I would think valves. They make a big difference as they change the compression presure.
My son is driving my '76 300D. He said it has started every morning as long as he let the plugs glow till the light went out (probably 60 seconds!). Not a perfect idle, but I'm sure I need to adjust valves again.
My '86 SDL is sitting outside this week so I guess I get to see how it will start tomorrow-supposed to be the coldest night yet. I just replaced the glow plugs, so they are good. Battery is old and weak. Means I gotta start on first try.

Rmcfarland · #10 11-12-2007, 10:49 PM

Well, I got my new replacement "pencil" type plugs today. I made jumpers to go between each plug from 10ga wire, and hooked them up via the old connector. I may put in a solenoid relay to handle the current, I'll see if it blows the fuse. I have a spare.

Not too bad of a job, really. I left the hard fuel lines in place, it might be easier if you removed them. This was on a 616 also, a 617 might be hard to get to those center plugs.

If you need the pencil style plugs for a older engine with the loop plugs, they are Bosch #80035.

Car started fine, but it was still warm from running earlier. I let it glow for about 10 seconds. I am excited for shorter glow times!

I will report back once I get to start it cold. Thanks all for your help!

Rmcfarland · #11 11-13-2007, 10:16 AM

Well, it got down to about 32F last night, I think. A little frost on the top of the car this morning at 7:45AM. I hopped in, glowed my new plugs for about 30 seconds and cranked. Fired on the second or third revolution and ran pretty good. So far I am satisfied. We'll see how it is once it actually gets cold.

One thing though.... the engine sounded......different, cranking this morning. Maybe a faster crank? Anybody else do this job and notice the same thing?

BenzDiesel · #12 12-05-2007, 09:04 AM

I would check my start of fuel delivery. With only 98,000 miles on the car, it should start on one cylinder. Check the start of delivery. If you didn't buy the car new, that is probably why you were able to get the car in the first place, hard starting because of incorrect timing and the owner got rid of it.

BenzDiesel

JimSmith · #13 12-05-2007, 11:40 AM

I tried to make this as straightforward as possible in my long post on page 2. These things need certain conditions to fire up, and if they have them, they always work. Always. If they don't they don't fire up. Ever. In between they become finicky as ideal conditions of one feature or the other degrades, and you get the effects of combinations of features contributing to establishing those critical starting conditions degrading, but find none that are all by themselves unacceptable conditions.

It seems you are either missing a vital condition or have several weak elements combining to prevent starting. I would suspect the rebuilt starter. I have purchased a starter in the past from FastLane and it was fine. I have forgotten what oil you are using, but if you have spent a few battery cycles trying to start your starter may be getting tired already and it is likely your oil is becoming contaminated with Diesel fuel. If the oil isn't becoming contaminated, that is your problem. No fuel.

Anyway, go re-evaluate how you eliminated the various players in this starting episode as suspects. It would be nice to be able to believe a rebuilt starter from Autozone would be ok out of the box, but we have heard rebuilds are not anywhere near 100% reliable, out of the box. Then you have stressed it a bit trying to start, so if it wasn't 100% when you got it, it is likely to have further degraded with this experience.

It is essential the starter spin the engine fast enough to build sufficient compression quickly enough to get the air hot enough to sustain combustion. This also means the valves have to open and close correctly. Valves typically close the gap as they wear (seats get worn, valves move further outward) so small gaps means valves are open longer. Set the gaps on the loose side, not the tight side of the tolerance. Use a 5W-40 synthetic oil. I use Delvac 1. Costs more, but if it helps avoid one of these sessions a year, it is well worth it to me. Check glow plugs. Oh yeah, check the glow plugs. the relay too.

And, I will repeat my old story with engine mounts. On my 1982 240D, the driver's side mount was sheared in half. So, instead of turning the engine over, the starter was lifting the engine, literally trying to turn it upside down, and then the engine would start to turn, too slowly to start. Once the compression stroke on one cylinder was past, the engine would sit back down on the mount and the whole process would start on the next compression stroke. That car wouldn't start under those conditions in the middle of the summer, and until I figured this out (actually just watched the starting process with the hood open and someone else in the car), I was ready to junk it. I got another 100,000 miles of reliable use from it after changing the starter (it was literally in pieces) and engine mounts.

This can be frustrating. There is no reason I know why your car should suddenly degrade to the point where it has lost compression it had last week, merely from changing the starter and the battery. Keep at it, these things are tough machines and it is much more likely there is some bit of data, some observation you are making that is misleading you than the engine has suddenly expired.

Jim

Rmcfarland · #14 12-05-2007, 04:53 PM

Well, after letting it sit for a bit, I thought about the situation.

Last week: car starts OK.
I bust the solenoid on the starter, and so I replace it with a whole new starter (not much more than just the solenoid).

Now: car won't start. Nothing else has changed. This starter is really about the only variable. So, I ordered another one from O'reilly's - This time I got the turbo diesel starter (I said 1983 300D, turbo). I will return my autozone one and get my money back, surely they will give me my money, it gave out in less than two weeks!

I will report back tomorrow or Friday when I get the new starter in.

toomany MBZ · #15 11-06-2007, 09:16 PM

If your primary filter darkens quickly, you may have fuel issues, critters living off your diesel. Replacing, replacing, replacing, will help that situation, add some bio-cide, perhaps.