1979 240D

I have a failing glow time relay - that will arrive tomorrow, in the meantime, I cooked my bettery with constant glow cycles and then on a charger for too long. Had a battery acid mess...


So I bought a new battery, but now the starter won't engage.

Battery voltage is 12.25V. When I put the key into the engage position, lights and radio dim, starter just kind of clicks. I also notice the wires are warm at the starter post after I disengage the key and feel them, but the solenoid is not warm at all.

So I took the starter out and to a McParts store to bench test it. It passed. I heard it spinning.

I looked at all the wires and contacts and they look ok - the cloth is a little worn, but no metal showing through anywhere.

What next?

__________________

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

Your battery voltage is low.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Thanks, I'll take it back tomorrow.
EDIT: kerry, I don't think that's it - I just checked the voltage across the battery in my 1980 240D, and it was 12.11

And I never have a problem starting that car.

__________________

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

Did you clean the posts and terminals when you installed the new battery? With voltage that low, it would not take a lot of oxidation to cause a problem.

12.11 is a dead battery.

12.75 is a full battery.

12.6 is a slightly low battery

if your 240 has 12.11 at rest, with the key off, and it starts, you have an amazing condition motor!

most diesel engines require a battery putting out at least 12.5 at rest in order to have enough power to turn over the engine fast enough to start after the glow plugs have been on enough to warm the prechambers...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

12.25 and 12.11 are both low for an 'at rest' battery.

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

Yes, everything is really clean and shiny. Also used a wire brush on the main ground point from the battery.

Like I said, The 240D sitting next to it in the garage never fails to start and has a lower voltage. With the weight of those batteries, it seems silly to yank the lower voltage one out of the red car to prove that b....

wait, is it possible that the cranking amps are low in the new battery? And that maybe they are higher in the other one, even though the voltage is lower?


@vstech - yeah that little red car has a little Stuttgart magic sprinkled in it, Never fails to start - and always felt peppier than my 300TD (with a turbo).

Still...how do CCA and voltage relate?

I suppose I should take the battery back no matter - if it is low?

__________________

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

Maybe your volt meter is out of calibration.

OK, took the battery back and they put it on the charger (twice the guy tells me) but assures me that it checked out ok

Got it home and it tested 12.5V

Still the same problem. New glow timer is in, and works fine, but when I push the key to the last position, everything in the car dims and I hear a little click, but the starter does not engage.

__________________

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

Your meters calibration might be off as well remember.

If the feed cable to the starter is warm or hot you probably have a shorted starter. Hold the key in the start position for twenty seconds and feel that cable. Rather than stress the battery start perhaps at five seconds and incrementally increase the time between feeling that cable.

Also unlikely but your engine is free? You can turn it with the crank nut clockwise of course? The dimming of the lights indicates the starter is getting substantial current.

I already know that the 'hot' terminal gets warm when I push the key into position.
The solenoid body remains cool. Is this consistent with a shorted starter? Would this be overcome during a bench test?

As I said, I saw the starter pass the bench test.

I will check the motor to maker sure I can turn it.

Not sure of any reason why it wouldn't turn?

EDIT: Can't turn it from the PS pump - belt slips.

Remind me how to get to the crankshaft to turn it without removing the fan/radiator/shroud
Also, if the engine wasn't spinning, wouldn't the solenoid or starter motor itself probably get hot?

How can I test for a shorted starter?

__________________

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

You probably dont want to hear this, but you can always swap the known good starter out of your other car & try that. Would let you know right away if the starter is bad, or you have other electrical issues.

__________________
2007 Dodge Ram 3500 Cummins Turbo Diesel 4x4
1994 GMC S-15 pickup 4.3 5MT
1985 300 SD
1978 300 CD
1962 220-S Fintail - awaiting restoration

Hold off doing much of anything until some more responses are posted. You have already had the starter off and it tested okay. It takes a substantial amount of current to heat a cable up. Or a high resistance connection in the vicinity of the heating when high current is flowing.

You can increase belt traction by rubbing the vee portion of the power steering belt with common face soap. Loosen the belt by reducing the adjustment of the power steering pump. Once the belt is loose soap all of the vee portion with the dry soap.. Then retension the belt fairly tight and try to turn the engine over again.

This is primarily because I suspect you have been at this issue for awhile since you had the starter off and it checked okay. You want to make sure that engine is really loose before going much further in my opinion.

If there is anything to perhaps do with this that you have not posted. Post it. You may also want to disconnect the glow plug circuit temporarily just in case it is involved it this somehow. If the engine were jammed up or the starter shorted the starter would represent almost a dead short to the battery and the cable would heat up. The starter having greater mass may not seem to heat at all as a result.

The thing here is you do not want to damage your battery by abusing it either. It is good to know that there is no reason to suspect an actual engine problem. Still the test should be done. Once that is eliminated the options of what may be wrong are reduced.

I'll just be nice and say it this way.

Cold Cranking Amps are different than Volts

You could think of it as a pipe filled with water. Voltage is the pressure of the water and amps are how fast it's flowing. So even more basic, Volts is how much stuff/how big the pipe is and amps are how fast the stuff is moving.

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Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]