No Start When Cold - PeachParts Mercedes-Benz Forum

McRoth · #1 12-23-2002, 01:02 PM

I've had a problem all this winter that my 82 240D won't start when cold, below freezing. I have to keep it in my garage all night so it will start in the morning. It's fine when I'm at work, sitting for 9-10 hours in the parking lot at below freezing temps doesn't seem to cause any problems. Last winter it started just fine all winter long, didn't even need to use the block heater.
When I try to start it cold the first crank, after 2 glows, it acts like it's going to start & then dies when I stop cranking. Then it doesn't even come close the second time. I think my battery is getting weak, could that be part of it? I just changed the fuel & air filters. Maybe it's not turning over fast enough to fire? It's probably no more than 40-45 degrees in the garage & it starts very easily.

Fisherman · #2 12-23-2002, 01:58 PM

A weak battery will cause you a lot of anguish. When the glow plugs cycle they draw a lot of power and then you are immediately going into the starter mode.
It might also be that you have one or two bad glow plugs. They are only about $12.00 each so can be a fairly cheap fix to hard starting.

McRoth · #3 12-23-2002, 02:07 PM

I kinda figured that might be it, I'll probably get a new one after work today. I just replaced the glow plugs last month, so they shouldn't be a problem.

Thanks!

P.E.Haiges · #4 12-23-2002, 06:17 PM

Have you checked the valve clearance?

P E H

Aaron · #5 12-23-2002, 10:07 PM

If your battery and glow plugs check out ok, you might consider a switch to either a 5W-30 dino oil or else a full synthetic such as Mobil 1 10W-30. Remember though, if you switch to Mobil 1, you're pretty much stuck using it for the rest of the car's life.

Stevo · #6 12-24-2002, 08:18 PM

Another thing is your starter needs to turn up, I think, 100 rpm. so it might be worth checking that. As Aaron said switching to synthetic will help.

McRoth · #7 12-24-2002, 11:48 PM

Well, I got a new battery yesterday after work, it really made a difference on how fast it turns over now, but unfortunately it didn't solve my problem! I left it out last night & this morning it STILL wouldn't start. It turned over better, but no go.
I adjusted the valve clearances this fall & set them to spec. I suppose it's possible that I didn't tighten some nuts enough & they've gotten off again. It has seemed like it's making more smoke than usual lately. I tried making my own wrenches for the adjustment, but I didn't heat treat them right & they kept slipping when I did the job. I think I'll have to order a good set & re do it soon.
Is 5W30 oil good for a diesel?? Do they make one for diesels that has the additives for soot suspension? Why do you have to stick with synthetic if you switch over to that? I don't think I've heard that before.

Thanks for everyone's help & suggestions!

McRoth · #8 12-24-2002, 11:49 PM

I forgot to mention, my starter is only about a year old, so that should be fine.

Palangi · #9 12-25-2002, 12:03 AM

You're not trying to start it on biodiesel are you? It might be like Crisco in cold weather.

P.E.Haiges · #10 12-25-2002, 10:10 AM

McRoth,

If you are not sure you tightened the valve nuts enough, you better check them right away before your engine eats a valve and spits it out the oil pan along with the piston like mine did.

No, I didn't do the valve adjustment, it was done by PO or someone he had do it.

It sounds like you might not be getting fuel to the injection pump. Try pumping the hell out of the manual fuel pump. You might have a leak in the fuel line and air is getting in the fuel system. Pumping the manual fuel pump may get the air out.

P E H

JimSmith · #11 12-25-2002, 12:19 PM

McRoth,

Diesels are relatively simple machines, and provided the essentials are there for starting they do well in nearly any temperature. From the description you have given, there seems to be a temperature threshold that affects the car's willingness to start.

You have addressed the first suspect, the battery. Next the items that are affected by temperature, low temperatures that is, are fuel flow, starting rpm, and possibly compression.

Fuel gets thicker and more prone to parafin precipitation as the temperature drops. In the teens the stuff can clog the fuel lines and not start, or even shut you down while driving. Consequently, good fuel, with a conditioner to keep the parafin in solution (or up to 15% gasoline) at the lower temperatures. Also, if you have a borderline performing filter, the lower temperatures will make it perform worse, also potentially leading to fuel delivery problems making starting harder.

Oil also gets thicker as the temperature drops, leading to higher pumping loads to get the oil circulation going, the load on the starter gets higher. This added load can slow the starter down, to the point where the heat of compression, which the engine relies on to burn the fuel, gets absorbed by the cold block as fast as the heat is generated, leaving the conditions inside the engine unsuitable for burning Diesel fuel leading to a no-start event.

Your valves are typically adjusted "cold" or at ambient temperatures on a warm day if you have the choice when doing the work. If you adjusted them on the tight side of the tolerance, they may be too tight when it is cold out. I adjust them a little loose as I live in a cold winter climate (my daughter in Upstate New York is using the car, also a 1982 240D) and it works fine that way.

You mentioned you have a new starter, and this is an area, if you check the posts on the subject, where you must be sure you buy from a decent supplier. Fastlane is great, but if you get their starter, get the one for the later 300 D, SD motors as they are noted as HD vs. the standard starter for the 240D. The higher rated starter fits right in, no problem. The issue here is how the rebuilders do the rebuilding. I have written on this issue before, but starters are rated for peak duty, not continuous duty, while cranking a Diesel for 30 to 90 seconds starts to look like continuous duty to the starter. It will overheat and damage the insulation, leading to internal problems with the wiring and its insulation. Most rebuilders do not address this, they just replace the bolt on parts. Bosch rebuilds do a better job, and replace old, worn wiring on the rotor and stator. This is a long winded way of suggesting your starter motor may be less healthy than you think and it could be contributing to the problem of slow starting rpm.

Some of your solutions are to look as noted above, for leaks in the fuel system, change to a synthetic oil (I highly recommend Mobil Delvac 1, 5W-40 but other Diesel specific synthetics are likely fine and lower cost - the Mobil 1 standard oils are not acceptable for your car as they are not Diesel rated - you would need their 15W-50 and possibly a 0W-40), for lower pumping losses. You should also check your vavle clearances and adjust them to the loose end of the tolerance.

I assume the car runs fine otherwise, so I doubt you have a really significant internal engine issue. On my 1982 240D I had some difficulty starting and it turned out to be broken engine mounts. I know this is controversial on this site but I am convinced half or more of the starting torque went into tossing the engine around in the engine compartment, leaving substantially less to rotate the crankshaft. It also led to a mechanically damaged starter. I replaced the motor mounts and the starter and now the car starts, admittedly with some protesting, at single digit Fahrenheit temps, not plugged in. It also enjoys an annual fuel filter change (about 20,000 miles) and runs on Delvac 1.

There is typically no single fix to this issue as any one can sometimes be overcome but together they can amount to too much of a hurdle. Hope this helps, Jim

Stevo · #12 12-25-2002, 04:05 PM

McRoth

one other thing comes to mind. does your priming pump leak when you pump it? if so replace it, $20.00. Air can enter the system through leaking hoses also. have you tried pumping then starting right away?

McRoth · #13 12-25-2002, 06:37 PM

Thanks for the long post Jim! A lot of good information. The car turns over much faster now with the new battery. I'm not sure who did the starter, I bought it from Advance Auto Parts.

Stevo, the priming pump does leak when I prime it, so I'll try that this weekend when I have time to leave it in the garage to warm up. I'll see about getting a replacement soon.

I'll definitely get a new set of valve adjusting wrenches & adjust that very soon. The car runs great other than this starting problem, I didn't have this problem until this winter, I had no trouble at all last winter, even in single digits without plugging it in.

dave240 · #14 12-25-2002, 10:46 PM

Hi McRoth,

You got some great suggestions above and there is little I can add.
Hovever, for the sake of irony, I recently went through the same situation.(same car too, 82'240d manual)
And like you, my car started great last winter in well below freezing temps.
This winter different story, glow plugs were not much more than a year old, valves recently done. Brand new powerful grp49 Interstate battery etc. And car would start right up at 50+deg. and below 40deg. I had no wheels....

I say, if you still have trouble after you've checked valves etc.
Put aside the fact that your Glow Plugs are new. Take them out individually and put 12Volts to each and watch them get bright orange.

It was intesting what Jim stated above(and more than likely true)

"From the description you have given, there seems to be a temperature threshold that affects the car's willingness to start."

This was exactly my situation, as all the components needed to make great compression were working fine, but it still would not lite-off. Why? Because despite my earlier quick tests to check glow plugs in the end I found 2 of 4 totally non-funtional. Hence the air and block temperature is critical for combustion.
Bottom line... MAKE SURE all your GP's work.
Sorry for ranting,
good luck
dave