Starter continues to crank W/Key OFF

redytrk

Veteran Expediter
Charter Member
Road service was getting me going after a Fuel line Gell-up. He asked me to crank the engine while he checked to see if the fuel was pumping. To my and his horror the starter continued to crank with the key off. We frantically disconnected the batteries,but by then the starter was TOAST.

Has this ever happened to you? Dealer says this is fairly common,and the only way to prevent it is to install a Quick disconnect switch.$100.00 parts plus $200.00 labor. The Engine is Mercedes Benz MBE 900.It seems the starter is not receiving enough voltage to tell it to shut off.

Your thoughts please!
 

bryan

Veteran Expediter
Hi

Yep I've had it happen.The bendix gets stuck.Usually tapping the front of the starter with a hammer will make it spring back.I didn't know it could be caused by low voltage though.Just always considered it a warning that the starter is going bad.
 

terryandrene

Veteran Expediter
Safety & Compliance
US Coast Guard
Sounds to me like the dealer has no clue as to how to fix a problem so he is jury-rigging it so you have a temporary solution to a continuing malfunction. Kind of like a little novacain on a broken leg...feels good for a while. If Mercedes had wanted a cut-off switch on the starter, they'd have offered it as an option
 

greg334

Veteran Expediter
This actually sounds like the solenoid was stuck or contacts welded together by the surge of current the starter needed when the engine is cold. I have had this happen a few times.

If you could have the dealer take apart or you take the solenoid apart, you may find that the contacts are fried. Voltage level has little to do with this.

The dealer installing a switch for $200 labor sounds excessive; this should be an hour’s worth of labor on the outside unless you want the thing somewhere that makes it difficult to place. I know that Volvo and FL both have options of complete power cut off for the truck.

Oh thinking about it, make sure that the switch is rated for the load of the starter. With three batteries (I have three) and a capacity of 2000 plus amps with the combined battery pack, I would think that some cheap switches I have seen would eventually fry out and catch on fire.
 

redytrk

Veteran Expediter
Charter Member
My information comes from 3 separate source's all say that all makes of Diesel engines can do this.

Source #1 Stoops FL Ft. Wayne In
#2 Koesters Ft. Wayne
#3 Blaine Miller Road Service

Don Bentz of Bentz Transportation products at first said such a thing could not happen.When informed of the 3 sources he said they were to be believed.

No one has suggested any fix, either in specking a new truck or after market other than installing a Kill switch.
 

DocRushing

Expert Expediter
On each of our two Volvo tractors, then again on our present Columbia D truck, when I wrote the specs, I included a master isolation switch (a factory option) for the batteries (four heavy-duty batteries).
I've conditioned myself -- trained myself -- much like one of Pavlov's dogs -- in such a way that, if an electric problem -- a real problem -- as, for example, a sudden unexplained odor of hot or burning insulation -- or if the starter motor ever continues running when it should not -- then I'll flip the isolation switch ASAP -- then investigate later.
The switch on the present truck is on the deck on the outboard side of the driver's chair.
That switch is also a neat way to make it slightly harder for a potential thief -- especially an amateur -- to steal the truck -- as, for example, while the truck is parked long-term while at home.
Best wishes to all,
Doc.
 

greg334

Veteran Expediter
redytrk
let me ask you this; was the truck running when the starter would not shut off? Or to phrase it better, was the truck cranking when this happened?

If the people tell you that this is a common thing, it really isn't. I find watching some of the maintainance that goes on with these trucks, I am surprised that they run at all. I know that people don't think about the starter soleniod being something that should be changed periodically, but I would say it should be at least removed and disasembled to be checked with the started every 200K or so.

The circumstances (and this will give you an idea how to prevent it) from your statement and what I gathered is that the truck was stone cold and you were cranking it. With that assumption, the starter will draw massive amount of current to turn a cold engine over, hence the problem with the arcing of the contacts and possibly welding them together in the soleniod. One reason for heaters and an APU that shares the coolant with the engine.

But with all that said, let me tell you about two of my experiences with Stoops Ft. Wayne. I had asked them to do an ECM dump on my soon to be truck. I got the service manager who told me that that can't be done because that is a factory only thing. So I went to Stoops in Indy and had it done.

The second thing is I had three keys made there and I did not have the orginal key when I did this. You would think that the keys would be all the same and they would check them against each other, NO. Two were the same and the third was cut slightly different, but not one of them fit my truck. I have no clue how they cut them but they supposedly did it from the VIN. I later returned to the place early saturday morning and got the right keys. Between the two things, I just don't trust them.

The other places I don't know about.
 

redytrk

Veteran Expediter
Charter Member
< redytrk
<let me ask you this; was the truck running when the starter would not <shut off? Or to phrase it better, was the truck cranking when this <happened?

Truck was off. Road service tech had line disconnected from inlet to filter. He asked me to crank the engine to see if the fuel would pump through the line. When he asked me to turn the key off,I did so but the starter continued to crank with the key IN OFF POSITION. Block heater had been plugged in, so the engine should crank as easy as possible.
 

Deville

Not a Member
That happened to me once, it ran for aout 20 minutes drawing huge amounts of power from the batterys and Alt was working over time to keep the truck from stalling, after it stoped finally i figured the starter was gone, but it was apparently a bad ground wire.The starter itself was fine. So strange. I did try to beat the starter with a hammer to make it stop it did not work. the starter lasted another year b4 it gave out for good in November.
 

redytrk

Veteran Expediter
Charter Member
well I just got the truck back.

The Starter was fried. The Good news, Covered under Warranty, part was 7 mo. old.

The Batteries were fried. The Good Hews, 100% Warranty covered. They were new.

I had the emergency cut-off switch installed.Every one seems to agree that this is the only thing that can be done when the runaway starter thing happens. (IE: Starter continues to crank even when key is turned OFF.)

The cut off switch can be installed as as factory option,and I would recommend it to any body specking a new M2.
 

greg334

Veteran Expediter
The really dumb question of the day is did you find out what really caused the problem or did the mechanics just become parts replacers?
 

Mudflap

Expert Expediter
Sometimes the contacts of the starter relay arc so much they weld themselves together, causing this condition. Most class 8 tractor based trucks have a main power switch to the left of the drivers seat- this should be required in all class 6 and above trucks as far as I am concerned, it's a definite safety plus. Mudflap
 

redytrk

Veteran Expediter
Charter Member
>The really dumb question of the day is did you find out what
>really caused the problem or did the mechanics just become
>parts replacers?

#1 -6 degree temp.
#2 Cranking engine 5 or 6 seconds for Road Service Tech to determine if fuel was pumping.(he had line from tank disconnected)As I have said before,the starter continued to crank even when the key was turned off.Enough time elapsed before we could disconnect the batteries that it Burned out the starter and one of the batteries.
#3 Power Service Fuel Supplement did not do its job. A call to PS in Houston determined I had been sold old formula by Tractor Supply in Oct 2006. This stuff even gelled right in the jug at that temperature.
#3 The new ULSD fuel mandated by our government has a gel point higher than the previous formulas.

I must add that hundreds of trucks went down in this area,about half of which claim they were using the recommended supplement. About 200 School Buses left the kiddies stranded.
 

greg334

Veteran Expediter
Sorry Rdytrk,
Let me rephrase the question;

Did the mechanics just replace the starter without invesigating what happened, either a stuck soleniod or a low voltage problem or just assume that the list you gave was the problem?

The cut off switch being used for a runaway starter is not a solution, it is a safety mechinism. Knowing what happened may help you in the future.
 

redytrk

Veteran Expediter
Charter Member
Greg...I was told they tested starter and batteries. The low voltage was blamed on cold weather and weak batteries.

I don`t come close to being able to determine if the Tech did his work correctly.
 
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