Freak Starter Barbeque.

[Fluxcore]

Hi everyone.

Two days ago, I had a strange experience:

I went out in the morning to start my 1988 F-250 7.3 IDI and after waiting for the glow plug light to go out, I turned the key the rest of the way to start up. After a little cranking, she just wouldn't start.

I know that it's not a good idea to crank the starter over for too long, so after a little while I turned the key back and the starter just kept cranking over by itself! I was totally cought by surprise and had no idea what to do.

I popped the hood and ran out in front of the truck and just watched helplessly as the starter kept right on cranking. Foolishly, I even tried prying the battery leads off of the batteries barehanded. No luck there.

By the time I raced back up to the 3rd floor and grabbed some tools, then raced back down to the truck, the crispy starter was barely turning the motor at all.

Toasted starter smoke is disgusting.



Anyway, it seems like there were two mechanical problems here:

1. The truck didn't start.

2. The starter wouldn't stop cranking.

I figure that either something failed inside the starter itself, or the starter relay solenoid got welded into the "on" position, or the ignition switch got stuck in the "on" position. Any of these problems may account for the starter refusing to stop cranking, but they don't answer the issue of why the engine wouldn't start.

My local Ford Diesel mech told me that on some engines there is some mechanism that senses when the starter bendix gear won't dissengage from the flywheel and it then tells the IP to withold fuel from the injectors. I think the idea was to prevent the engine from firing up and grinding gears off the starter, the bendix, or the flywheel. I have no idea if such a mechanism exists on my old 1988 7.3 IDI engine or not. I'm thinking it would only be found on the newer digitally controlled IPs, not on a purely mechanical IP like my Stanadyne DB2. Does anyone here have any knowledge of whether my old engine actually has this mechanism? It is important to me because if it does have one, then there is only one problem to fix, not two.

There is a second possibility of why the engine wouldn't start. A few days back, I topped up the second half of my fuel tank with 100% biodiesel. This effectively means that for the few days preceeding the problem, my tank was filled with B50. Properly brewed biodiesel is known to not only have excellent lubricity, but also powerful solvent properties. I'm wondering if the engine didn't start because the biodiesel cleaned a bunch of crud out of my fuel tank and fuel lines and dropped it into my filter, effectively starving the engine of fuel? Another biodiesel related explanation of why the engine never started is that perhaps the crud cleaned out of the fuel tank somehow jambed up my fuel solenoid valve. Still yet another biodiesel problem is that maybe the biodiesel ate my IP seals, although I don't think it could happen over only 3-4 days. I don't even know if my old 1988 DB2 IP even has Viton seals, or not?

If anyone has any input or advice on this issue (or issues) please jump in.

[88beast]

another guy idr if it was here or on the 6.9s had this happen receltly

[Bill1013]

My starter stuck running a couple of times, (reman starter) I hit it with a hammer and it released. The solenoid on the starter must have "welded" the contact, it's only like a copper washer. My engine did start. I would say that the biodiesel is your problem, take your filter off and see if it's plugged full of crud. My starter is an Autozone reman. I'm sure someone will chime in with a better one, maybe.

[91diesel]

These trucks dont have that safeguard. I am 90% sure they dont at least. The starter gear will disengage once the flywheel is turning faster than the starter drives maximum speed.

Funny...my starter stuck on once too. I had a 13mm wrench handy and hood was open so i was able to shut it up quickly. I think its my ignition switch down on the column may be different for you. Mine USED to keep running or randomly the in cab lights would stay on for about 5 seconds then shut off once you turned the key back. Totally random though. It has not done it for a long time now...i replaced the lock cylinder. It did it i think once after i replaced that.

My cousin has been running straight vegetable oil for about a year now and has not had any problems with seals. His IP is tired and coughs on diesel but starts right up on vegetable oil. Dont think bio has any effect on seals personally. Truth may be different. Vegetable will polymerize copper and some other metals. including steel. I dont know if bio will do it. i dont think it will. Veggie oil takes more than a week to even start to show the green goo from the process of polymerization. dont ask me how it works [img]/forums/images/%%GRAEMLIN_URL%%/laugh.gif[/img]

Truck not starting could just be a coincidence. or a common problem which i would look at after i got a new starter and fixed the starting system.

anthony

[Kaliburz]

Either the switch had an issue or the fender 'starter relay' didn't let go when the key did (as in fused it's self). A tap on that might have dislodged it, who knows. (Had that happen to me on a 3208 Cat starter in cab over Ford, had to remove batt cable. Issue was not enough juice from starter to get the old gal to spin over... el weldo starter.)

[cdnsarguy]

How fast was the starter turning the engine at first start.......must be over 200rpm..... did the GPs cycle as normal..

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">By the time I raced back up to the 3rd floor </div></div>

And this is why I carry a small adjustable and 5/8" wrench in my consol.......

My first choice would be to check the ignition switch operation at the fender starter relay.... this can be done by using a test light at the power wire to operate the starter solenoid.....small single wire usually with a 90* connector. Do this proceedure several times.

If there is correct operation of the ign switch, I would replace the relay.... as preventative maintenance.. cheap fix. The starter mounted solenoid could be have been the problem also, but you will be getting a new starter anyway.

[Fluxcore]

One more thought here:

I met a lady mech the other day who told me that Fords have notoriously weak starters. She said they MUST have at least 11 volts AT THE STARTER, or else they eventually get fried. Eventuall, in this context, means sooner, rather than later

She told me that the surest fix for this is to rewire the starter circuit with "OO" wire (welding cable), rather than the smaller "O" wiring that the factory uses.

Apparently, you can get "OO" connector at auto houses and yank out your original puny starter wiring and just lay out the old wire on the floor, then lay out the new heavy wire right over the old stuff and cut it exactly to length. Peel back the ends, install the connectors, reinstall the heavier starter wire and your starter will be the better fror it.

Can anyone verify this info?

[Discbrks]

there may be a "little" truth to that, but the OEM battery cables are fairly big... I know they're bigger in diameter than the batt. cables on my '99 Ranger.

[arthurgoboom]

Nobody discussed the outside temperature at the time. I know it's super cold here. Biodiesel has a much higher cloud point than petroleum diesel fuel, so your B100 may have been gelled up when you tried to start the truck. Also, if it's below about 40 degrees you probably needed to double cycle the glow plugs. Personally, mine starts better with 2 cycles of GP no matter what, even when it's 80 degrees outside. IH says these engines should start unassisted (i.e. without using block heater) down to 20 degrees F. Don't be afraid to use 2 or even 3 cycles to get started (I like to wait about 5 seconds between cycles to let the heat bleed off into the prechamber, so as to not overheat the glowplugs).

How long did you continue cranking before you let go of the key? If you held it too long w/o starting you may have indeed welded the solenoid contacts together.

[asauer]

Yes, it has definitely been COLD here the last few days- and I hear it's only to get worse.
I have NEVER had to cycle my glowplugs twice, no matter the temps...not even when I forgot to plug my truck in when it was 0 out a few years ago. I always plug it in, however, because it's so much easier on everything.

[Kaliburz]

When the local JD parts man use to make HD batt cables, nearly EVERYTHING I touched ended up getting '00' (Friends F150 w/ 4.9L got a '00' ground cable made and installed- he was in the big city and I mailed it to him- big city shop mechanic's eyes went BIG when he saw it). I can't believe how much cheaper things were then (1990's) vs now. Dealer closed, but a local batt shop makes custom cables. Man, EXPENSIVE.


I think EVERY starter needs the correct voltage or issues will crop up. It's prob. more the issue that folks will tend to try to crank the engine over 'longer' in hopes it starts. This extra time, no matter how short, allows the contacts to get warm- and weld if you are not careful.

[Fluxcore]

As an update, today I towed the truck over to the starter place that had just installed the new starter about a month ago. They installed a new one and when the battery leads were reattached, the starter never started cranking. That was a good sign as it indicated that the starter relay solenoid was okay, after all. The mech tried to say that after the leads were removed a few days back, then the solenoid could have become unstuck again. I started the truck and shut it off again a few times with no problem.

They honoured the warrantee as there was no proof that the relay solenoid caused the previous starter to fry. At least I never had to pay for a new starter, but tomorrow I'll replace the old relay as a preventative measure.



Kaliburz, thanks for the tip on not cranking for too long. I knew it was bad to do that, but I never knew exactly why.

[Phillipmc1268]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fluxcore</div><div class="ubbcode-body">Kaliburz, thanks for the tip on not cranking for too long. I knew it was bad to do that, but I never knew exactly why. </div></div> Just to add to Kaliburz, starters are not continuous duty electric motors. An electric motor with 100% duty cycle (duty cycle=% of 10 minutes an electrical component can operate under load) to match the torque output would be heavy, huge, and expensive. It's theoretical anyway because the batteries would drain pretty quickly.

Two related principles cause starters to heat up and fry. When the starter heats up from being used, it's internal electrical resistance rises as well. This requires more amps from the battery to spin at the same rate. More amps generates more heat and the cycle of doom continues, but there is one other thing to consider and that is battery voltage. As the batteries drain the voltage goes down, this also requires more amps to make the starter spin adding to the cycle of doom.

The larger battery cables help by reducing the resistance of the circuit, resulting in higher voltage at the starter.

The starter was not at fault here. The relay on the fender had to be engaged for the starter to spin. It stayed engaged in one of two ways: A faulty ignition switch or the fender mounted relay is was stuck closed. My bet it was the relay. I know you said you were going to change it anyway, but to make sure you go ahead and get it done, there is a chance that if it was stuck then broke free that the contacts inside are probably burnt, increasing resistance at the relay. Hate to see you trash another starter.

[asauer]

Sign_Man- a higher resistance in the starter would lead to LESS current draw, not more.

Ohm's law is the good 'ol standby that solves this problem...

Voltage= Current x Resistance

For our case, let's say our voltage is 12, the resistance (of the starter) is .1ohm, and we don't know how much current is required.
Solving the equation finds our current draw for the starter to be 120 amps.

Now, let's say your batteries are becoming weak and only supplying 10 volts. For arbitrary purposes, we'll assume the starter has not been heated up at all, and resistance is the same at .1ohm. Plugging these new values into the equation gets a result of 100 amps.

Therefore, starter current draw does NOT go up as the battery voltage drops.

Copper has a positive temperature coefficient, in which resistance increases with temperature. I would have to look up the values for copper, which is what the motor windings should consist of, but I'm sure it's pretty much negligible. Either way, you're drawing less current than a cooler start motor.
The problem is NOT drawing too much current through the starter motor windings which causes them to burn up, it's running the starter for longer than you should. Even though the starter technically draws less current when it heats up, it is this very principle which does the motor in. Since the coefficient is not that high of a value, the resistance does not increase enough when the motor starts getting hot. If the resistance would increase high in proportion to temperature, the motor would be 'self regulating' and prevent overtemperature, much in how a thermal fuse works.

Sorry for the babbling, but I wanted to set this straight once and for all. I hope this clears everything up.

[suv7734]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sign_man</div><div class="ubbcode-body">[quote=Fluxcore]

The starter was not at fault here. The relay on the fender had to be engaged for the starter to spin. It stayed engaged in one of two ways: A faulty ignition switch or the fender mounted relay is was stuck closed. My bet it was the relay. I know you said you were going to change it anyway, but to make sure you go ahead and get it done, there is a chance that if it was stuck then broke free that the contacts inside are probably burnt, increasing resistance at the relay. Hate to see you trash another starter. </div></div>

The glow plug/starter relay on the fender was not the cause of the failure here. Once the starter mounted solenoid 'welds' together the starter will crank as long as the battery is connected. If it was the the relay the new starter would have dispayed the same symptoms as the old one. The common failure on these starters, when this happens, is the solenoid mounted on the top of the starter because that is where the most current is running and the heat is generated. If you take the old starter and connect it to a battery I will bet it cranks over without the solenoid being triggered.
The amount of current running through the fender mounted relay to the solenoid on the starter is minimal because it only powers/triggers the solenoid hence the small wire running down to the starter. Depending on the condition of the batteries the amount of current being passed through the starter mounted solenoid can go from lots to OMG in a big hurry, meaning a lot of heat.
I'm not saying it's not a good idea to replace the relay as a P/M measure, just don't expect the starter to stop turning if you disconnect the wire from the relay if it ever 'locks' again.