So... had a strange thing happen while at work today. When I went to take off from where I had had lunch, my ignition key did not work the first couple of times after the customary glow-plug warm up indicator sequence. I thought this a little strange since it has always just worked fine with the exception of once when a glow plug gave out. On the third try it finally worked, so I thought to myself, "perhaps the ignition switch is starting to act up a little bit?, I should watch that"...

When I got back to work only a mile or so away and switched off... I heard this weird low rumble/vibration noise. At first I thought perhaps my radiator fluid was boiling like crazy... but it's not that hot here and i hadn't driven for that long at all... I popped the hood and it was such a strange noise... almost as if the engine was still running, but it wasn't?... I think I saw that one of the glow plug posts or wires was starting to glow red-hot... I couldn't figure all this out and had to get back in to work, so I quicklly disconnected the battery... sound stopped.

I was hoping that after cooling down for a while the problem would go away, but after work, every time I tried reconnecting the battery I would get the same sound. I narrowed it down such that I'm almost certain that it's my starter motor spinning very fast and making a disturbing racket...

I had to leave the car at work... and I was hoping that some awesome benz-nerd here in this great forum could help me out with this perplexing problem?

What do you all think of this one? Should I try hammering on the starter from below perhaps... checking a relay... what could be causing this circuit to be still engaged with the key turned to off or not even in the ignition?

Thanks all... hopefully I can go rescue my car tonight and not leave it out in the sketch area where my company is...

Try giving the solenoid (the large round bump on top the starter and below the manifolds) a whack. It may be hung up- but when it is engergized and pulls the contact down to power the starter it also thrusts the gear into the ring gear on the flywheel. The solenoid is not hard to change - it's held in by a couple of screws. Are you certain the starter is running? They source a fair amount of current even without a load on them so you should have had a substantial arc when you disconnected the battery. If you decide to hook the battery back up put your hand on the starter to see if you can feel it rotating. They are not designed to run continuosly so it should produce a noticeable amount of heat within 20 to 40 seconds of running.

__________________
1982 300SD 180K, rebuilt engine
1973 450SLC Megasquirt
1990 Volvo 780 - 273k
1993 Volvo 240 Wagon - Scrap yard slumber

http://www.fuelly.com/sig-us/44619.png

Yes, I think it was generating significant heat.

I am not near the vehicle now, as I had to leave it at work. Whacking on the solenoid is one thing I could try, but this does not seem to indicate why the starter/solenoid would even be activated or not when the key is turned all the way to off?...

What it seems like to me is that the starter motor is now permanently activated, but the solenoid is not active so it is not forcing the gear to engage it's flywheel teach on the engine to turn the engine?

I also do think that there was/is quite a bit of arc/reaction at the batter lead when I was doing this. I wish I was near the car to confirm this all once again. The noise it makes is quite disturbing however, so I don't like to reconnect it much at all...

Turning my key seems to produce almost no reacting or engagement now.

Are there not some relays or other things I could try to narrow down this problem?

Shoot... thought there might be more interest in this problem...?

I don't believe there is a relay between the ignition and the solenoid, the solenoid in itself is a relay. My thoughts are the contact portion internally is jammed or welded itself together. I think (but may be wrong) the metal plunger within the solenoid (the part that engages the gear) acts on the contactor portion. If you suspect the solenoid is recieving power you can break its feed. If you look on the "frame" you will see a black box with a few wires running to it. Pop the covet and look for the two blue wires that are joined on the terminal strip. These are the wires that energize the starter solenoid. Take the screw out of the strip and seperate the wires. If the starter stays energized you need a new solenoid.

Good luck

Nick

__________________
1982 300SD 180K, rebuilt engine
1973 450SLC Megasquirt
1990 Volvo 780 - 273k
1993 Volvo 240 Wagon - Scrap yard slumber

http://www.fuelly.com/sig-us/44619.png

Thanks... are you speaking of the fuse-strip that's above and over the engine on the firewall? It's like a big peice of metal wtih some wires going into each side of it?

I looked at that and noticed that it seemd to be a little bent, as if there had been some serious current almost melting it... it has a little black flip-up housing/box that covers it.

So if it does turn out to be the starter solenoid, am I pretty much stuck until I can get it replaced?

I can't imagine there is any way to rig up a trick to get it started again and moving, aside from a push start? Seems like a push start might be near immpossible in a deisel, unless it happns to be aimed down a hill and you can get current to the glow plug system?

It will push/drag without glowing.

What I would do:
Disconnect the fat wire to the starter, or the battery
Turn the key to on
Get up to 25 mph in neutral, shift to "s" or "l" per your owners manual. Once the car appears to be running shift to neutral, stop, and disconnect the tow hardware. or if theres a suitable hill tow it to the top then coast down to start.
Drive to your shop of choice without shutting down on a hill.

__________________
James Marriott
2003 Buick Regal
1983 300D (228k, frau Auto)
1996 Suburban K2500 (192k, 6.5 turbo diesel/4WD towmaster 10,000)
www.engineeringworks.biz
1987 300SDL junker 170k
1982 300SD junker, 265k

Im wondering if the ignition switch is the culprit here. Since it is also powering the glow plugs relay too.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

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Thanks for tow-start instructions... I may have to use them.

Is it difficult to accomplish a solenoid replacement with the side jacked up and crawling under there? I'm hoping to save as much money as possible and do anything/everything I can myself if you catch my drift...?

The terminal strip I speak of is on the "frame" by your alternator on the same side as the starter.



Edit: The solenoid power is in the top position on the strip as viewed from the front of the car. There is a somewhat thick white wire with a fiberglass jacket and two purple wires. The bkue are part of the alternator circuit to excite the field. (just upgraded my alternator to a 100 amp so had the blue wires on my mind )

__________________
1982 300SD 180K, rebuilt engine
1973 450SLC Megasquirt
1990 Volvo 780 - 273k
1993 Volvo 240 Wagon - Scrap yard slumber

http://www.fuelly.com/sig-us/44619.png

The cylinder on the top of the starter is the solenoid just so you can see where it sits.

Attached Thumbnails

 

__________________
1982 300SD 180K, rebuilt engine
1973 450SLC Megasquirt
1990 Volvo 780 - 273k
1993 Volvo 240 Wagon - Scrap yard slumber

http://www.fuelly.com/sig-us/44619.png

So... I went back to the car this evening and tried some fiddling with things. I jiggled the key in the ignition some, and also rapped on the solenoid from above some.

One of those things I did enabled me to connect the battery back up without the crazy spinning of the starter motor. I wasn't able to re-start the car though... it did the whole glow-plug warm up, but wouldn't even make a sound on that last key-turn.

I suspected that the battery has been drawn down quite a bit, so I pulled it out for recharge overnight. I'm hoping that the battery was so low that it just didn't have the oomph to make that first engagment of the motor and spinning of the engine.

Anyway... seems like my solenoid may need to be replaced...are these expensive, and is it possible to install from above or below by a home mechanic with moderate skills?