Cold weather starting issues, signs of starter wear? - PeachParts Mercedes-Benz Forum

tomas_maly · #1 12-13-2011, 01:05 PM

I'm noticing with my 1983 300SD that it's been harder to start in the morning when it's 25 degrees F out. I haven't changed or tested the glow plugs since I purchased the vehicle (6 months ago), but have noticed that turning the glow plugs on several times doesn't help and that starting the vehicle requires holding down the ignition key into 'START' for probably 30 seconds. The engine cranks and slowly, slowly starts gaining a higher pitch until it finally catches and ignites, when I need to then keep the gas pedal down for probably another 30 seconds before it will stay on without stalling.

Besides changing the glow plugs, is there is a way for me to recognize (or test) that the starter is wearing out? Maybe something using a multimeter? I have two starters, one on a running vehicle, one on a dead vehicle, and I was hoping to check both for quality.

If the starter is wearing out, is that something I can repair, if I so have the ambition (and electrical knowledge)? I have a spare starter, but there's a chance it is somewhat worn down also, and I was hoping to get it into an optimal condition onto my vehicle this winter.

Is it normal for me to have to hold onto the gas pedal for 30 seconds before the engine will stay idle/on without stalling at a cold temperature? Or is that a sign that the glow plugs aren't doing their job so well?

Should I be turning the glow plugs on 2-3 times, and will that make it start easier (without stalling)?

tomas_maly · #2 12-13-2011, 01:08 PM

I'm also noticing on the vehicle in general that after not starting it for a while (several days, etc), even in the warmer weather, it's a bit hard to start and blows white smoke. What might that indicate?

josha37 · #3 12-13-2011, 01:43 PM

white smoke on start up is insufficient heat for combustion on maybe one or more cylinders. i vote glow plugs or low compression... maybe both. If it is turning over fast enough to start i would highly doubt you need to be looking into your starter/battery/ or anything related.

tomas_maly · #4 12-13-2011, 01:57 PM

The car has 375k miles, if that helps. It seems to have been kept in really good condition (at least engine wise), when I got it, it zipped with quite a bit of acceleration, even though lately it's been not so responsive. Probably needs a valve adjustment.

The engine definitely cranks, but it just doesn't ignite, at least not until after 20 seconds of cranking. Almost like there isn't enough fuel pressure or it's not warm enough. Cranking it for 20 seconds gets it started a lot easier than just relying on the glow plugs alone - maybe an indicator of bad glow plugs?

Daman858 · #5 12-13-2011, 02:36 PM

You got it, dude, get them valves adjusted...numero uno for cold start problems.

kerry · #6 12-13-2011, 03:15 PM

Step one: test glow plugs.
Step two: do a compression check.

Air&Road · #7 12-13-2011, 03:35 PM

Hard starting is highly more likely to be the result of low compression and glow plug system problems than a bad starter.

Biodiesel300TD · #8 12-13-2011, 04:15 PM

Quote:

Originally Posted by kerry

Step one: test glow plugs.
Step two: do a compression check.

I concur with kerry but will add that you need to do a valve adjustment before you do a compression test. The valve clearances on these cars get tight over time, which makes the valves not seal completely, causing lower compression. Also make sure your fuel and air filters are fresh. Any restriction will compound cold start issues.

piccolovic · #9 12-13-2011, 08:17 PM

Also note that there's been bad fuel going around the last three months, which smokes white!!! Try adding some cetene booster (gray bottle) to your tank and see if that also helps. When I was in Fargo, ND, I noticed that the battery was going down and acting the same way . . . a hesitation before it kicks in the amps needed.

Diesel911 · #10 12-13-2011, 08:30 PM

The Brushes inside the Starter can be replaced as can the Solenoid. However, a new Solenoid is expensive.

Members have said that using Synthetic Oil allows for higher cranking speed in Cold weather.

Also when the Starter is cranking your Glow Plugs are also supposed to be on as there is a purple/Violet wire attached to the Solenoid circuite (at least there is on my 123).

Was your Glow Plug Light acting normal?

Use only Bosch or Beru Glow Plugs and use a Glow Plug Reamer or some alternative method to clean out the Carbon from the Glow Plug Holes if you want your Glow Plugs to last.

With the kind of milage you have if the Injectors have never been rebuilt they are past due.

kerry · #11 12-13-2011, 08:32 PM

Quote:

Originally Posted by Biodiesel300TD

I concur with kerry but will add that you need to do a valve adjustment before you do a compression test. The valve clearances on these cars get tight over time, which makes the valves not seal completely, causing lower compression. Also make sure your fuel and air filters are fresh. Any restriction will compound cold start issues.

The advantage of a compression test prior to the valve adjustment as well as after is that you'll learn whether the valve adjustment made any difference in compression.

vstech · #12 12-13-2011, 10:05 PM

all good suggestions.
a search here under funola should turn up a thread on testing starter spin speeds.
also amp draws, and glow plug testing.
there is also a great DIY on rebuilding the starter.
it sounds like you have some valves out of adjustment, and you are using DINO oil.
synthetic oil flows better at cold temps, and is easier for the starter to push during cold spells.

tomas_maly · #13 12-21-2011, 01:34 PM

I did a valve adjustment this morning and when I tried starting the car, it was not any better than normal. It was maybe 45 degrees outside (got to maybe 35 last night) and took several attempts to start it.

The glow plug indicator stays on for maybe 10 seconds, then goes off. Since it's not a valve issue anymore, I'll check the glowplugs next.

Problem is that I don't have a known functional glow plug to compare it off of to tell me whether I have a good/bad plug or whether I just don't know how to test them properly. I tried taking the relay wire socket out of the relay, and tested resistance from each hole to the nut on the glow plug, but never could get consistent results. Sometimes it jumped around to .9 ohms, sometimes it just stayed in the .3-.7 milliohms, sometimes just stayed at 0.

What is the easiest way to test the glow plugs, without taking them out and checking resistance (instead of current as I've seen some howto's suggest)? I remember testing my other car by having the negative multimeter cable on ground (on top of the secondary fuel filter), and having positive on either the threading of the glowplug or the nut. I don't quite remember. I also don't remember if I had to keep the relay running by having the ignition in ON, or not.

I also had a batch of plugs laying around from an old vehicle and I suspect some were good and some weren't.... Problem is that I could never get a consistent resistance reading with the multimeter whether I was touching the exterior threading to the interior threading, to the plug tip, the nut, etc. None of the tutorials I've seen out there really explain where to touch them.

Then again I may just have all bad (or failing/weak) glow plugs and so I'm just needing a good batch to check against (and maybe the guy at the store explain how to test them). Is it possible for the plugs to slowly stop working (and if so, how would I notice in terms of readings), or is it all of the sudden?

After I rule out glow plugs, what might be next to check? I don't think compression is an issue because once the car is on, there are no power issues.

It's also possible the injectors are original (375k miles), and so I don't know if them having old tips would cause issues starting. Also, I'm wondering if maybe something with the pump could be at fault, too. Though I don't notice anything odd after it starts.

When I start the car, the engine always cranks, but I'm not sure if maybe the starter is playing a part by not cranking it hard enough? And if that's at all possible, how I'd check the starter.

WINGAS · #14 12-21-2011, 02:14 PM

Put a trickle charge on that battery. Doesnt sound like its getting enough run time to properly charge it. Check/clean all connections.

tomas_maly · #15 12-21-2011, 02:28 PM

I've been hearing odd squealing (every now and then, but sometimes continuously at a low RPM) at the alternator, as if the belt were loose. So maybe it's not re-charging normally.

I will check the voltage before startup - my understanding is that it should be ~12.4-12.6V (or more), and really not any less. I will also try starting it with a battery charger hooked up to see if that makes a difference.

I do typically run the car for an hour at a time, but since I've been hearing the alternator belt somewhat loose, that might be an influence. My understanding is that if the alternator is functioning, the voltage should spike to 14V+ while running.

I do suspect that there are several things the problem at the same time; I've had the car 6 months but haven't done any maintenance yet (beyond fluids/filters).