I had started a thread with this problem, but the title isn't really relevant anymore, so I wanted to start a new one.

I had been noticing intermittent starting issues where I would have to turn the key to full off after the glow cycle (especially the first of the day) and then quickly to the start position to get the starter to turn. Eventually it seemed like the glow was lasting a really long time and I thought maybe it wasn't timing out and was preventing the battery from pushing ehough amps to turn the starter. Still, I was always able to get it to start.

Of course the one time DSW took the car, she drove my daughter to school, and then it would not start when she got back in. That afternoon, I whacked on the starter a few times and got it to start, drove home, then nothing.

Gurus here suspected a weak battery and that seemed right. This battery was not sealed and I had let it get a little dry. So I watered it.

It was holding at 12.4V at the terminals (same on the + & - main leads). When the car is running, the voltage is 14.2V. Right after I stop it it was about 13.1V.

At that time I suspected the starter, so I took it out and had it bench tested at the auto parts store. The tech tested it 3 times and it passed every time.

So I took the battery to the auto parts store and they put it on the charger to 'top it off'. When I went to pick it up the charger said the battery was charged and good, but it had boiled over. So they did a warranty swap and gave me a new one off the shelf. It read 12.4V before I put it in the car.

Put that one in and again, nothing. All the indicator lights come on, the glow cycle is normal, but when I engage the starter the dome lights dim a bit, but no click...nothing.

So I thought maybe the battery was under charged or under powered (it shows 765 CCA on the label, but other batteries I have used in these cars are more in to 800-900 CCA range. So I took the battery out of the 1980 240d which works (started the car with it this week) and swapped it in - same thing. No start.

So now I have: a new battery, a tested starter, and an alternator that cranks out 14.2V (but that doesn't matter right now since I have a new battery, right?). What should I do next?

Edit: one thing that I just remembered that might be relevant is that VERY intermitttantly, while driving, I would lose all electrical power for a second r two. Radio and blower would cut out. Then everything would pop back on again. Haven't noticed it over the past week or 2, but it seems like it could be related?

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

Had this same situation and it turned out to be a battery....but since you checked that and the start is good....the only thing it can be is a bad connection....

replace the battery cables, upgrade the gauge when you do it...

clean the ground straps....chassis to battery and trans to chassis connection...

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That sounds like a bad ignition keyswitch or electrical switch.

Try moving the key gently around, with the car running, to see if you can duplicate it. A bad electrical switch can cause some fun symptoms.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

With a known good battery, what exactly happens when there is no start? Just a click? Nothing? Cranks but won't start? If just a click or nothing, then the connections are definitely the next logical thing to investigate.

A 765 cca battery is a bit small, but it should work if no other problem exists and outside temps aren't too cold. A 12.4 surface charge indicates about 85%, but that's not unusual off the store shelf. Probably good enough to get the car going in warmer weather, but needs a good run to get it charged up.

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'79 240D

Not sure which of you vehicles you are speaking of. On the 1980 the Glow Plugs are on during Cranking even if the Glow Plug Relay has timed out.

I think the 1979 also has that feature.

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84 300D, 82 Volvo 244Gl Diesel

Indeed. That little bit added to the OP does change the game a bit.

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'79 240D

Thanks everyone,
This is in my 1979. It has the old-style GP. They do seem to work ok, I think the timer not timing out when I engage the starter my be related to the ignition switch

Glad I added that part about the power loss while driving. The cables are totally clean (cleaner than in the 1980 which starts right up with either battery).

I will swap out the ignition switch. I think that is the problem when I consider all my issues together.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

yes but can also be intermittent connection of the batter cable and or ground strap. If the headlights also cut out with the radio, then it is not the ign sw.

zeke, that was a lot of work taking the starter out to be tested. How was the test done? What kind of machine? What was measured?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

@funola....Ha! yes it was. Luckily this is a 240d, so I didn't have to deal with the turbo in my way. It was tested at one of those all in one machines at an O'Reilly's - the kind that do alternators and starters. There was no hint of a failed solenoid. It spun immediately on each test. (The motor itself is fine when it cranks).

Unfortunately, I can't remember the power loss happening in the dark - I am sure it has, but I don't remember if the headlights went out or not - I think the console lights went out, but I am not 100% sure.

I will test the continuity at the ground cable attachment point to the + terminal, but I did loosen and tighten the attachment bolt back again and it was totally clean.

Right now it is immobile....I can't get the car to start at all - no click, nothing. and all the cabin lights are strong (I'll check the headlights when I get home). So I can't jiggle the key to see if I can reproduce the power loss.

The local dealership has the switch in stock at a competetive price (and it's less than a mile from my house), so I am going to go ahead and replace the switch.

Can someone remind me what position the key should be in to unplug it? I remember having it in the wrong position on another car and all the wire leads popped out and it was a b@#$h to get them all back in and in the proper ports.

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

As funola said the Cables.

Battery Cables like to get corroded or eaten up under the inslation; especially on the ends that connect to the Terminals.

If you put a slit in the insulation and peeld back the Insulation you might be supprised what you find.

Slighly off subject. I replaced My Battery to Chassis Ground cable with a used one and it added one Volt to my Charging. So there Must have been some resistance in My old Ground Cable.

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84 300D, 82 Volvo 244Gl Diesel

I can easily swap out the ground cable from my 1980 (hot cable is obviously more difficult). The 1980 works, but I can tell you from visible inspection that the 1979 cables look practically new. This car seemed to have been something of a garage queen for the PO. The 1980 cables have some signs of green corrosion on the exposed part that goes into the terminal, and the terminal is off-color. The 1980 works, the 1979 doesn't.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

I hate fixing problems by trial and error. It's more work and can get expensive. Better to do proper diagnostics first and try to isolate the problem. I'd say don't replace the ign switch just yet.

The first thing to do is get an alligator clip of 10 gauge wire to the small terminal of the starter (terminal with the 8 mm nut) and when you have the no start problem, connect it to battery + terminal. If it starts, then the problem is probably in the circuit from that terminal back to the ign switch, which includes the wires and the terminals, the NSS , the ign sw.


Don't bother testing the ground strap or battery cables with a meter. I'm sure ou do not have the proper equipment for that. An ohmmeter won't do.

What you can do is add another ground strap in parallel with the old one and clean or replace the battery cables. Or you can do some voltage drop tests but that requires certain skills for proper interpretation of the results.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Don't go replacing anything yet.

Get a test light and hook it up to the starter solenoid, and ground the other side. Turn your key to start. If the test light lights up, you're getting power to your starter, and regardless of how it tested, you probably need to replace it. If it doesn't, then do what Funola has suggested and jumper the starter solenoid directly.

I'll also second what Diesel911 said about a cable looking pristine on the outside, while the "conductor" inside is just a bunch of green goo.

I had an intermittent no-start problem with my 617 powered truck. Once the starter got hot, it wouldn't crank fast enough to start the engine. Acted like a dead battery - jump start it with something else and she'd crank right up. Starter tested fine, 100% factory spec. I replaced it anyway, zero issues since.

Not saying your starter is for sure the problem(Funola's jumper test will confirm that.). Just saying that it can test just fine at the auto parts store while still being flakey.

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617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap

Well it was the starter after all. Switched starters between the two cars and the 1980 didn't start and the 1979 did. So the starter is bad, even tho the bench test passed it. Trip back to the O'Reilly's tomorrow to get a warranty replacement.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT