This Start Problem....

Tbaumer

Well-known member
Might be a dumb question, but do starters have a thermal cut out? Get too hot & a safety opens a circuit until it cools down? Most AC motors do & the safety switch can get weak & "nuisance trip".
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
I’m contacting RD for one of his high speed units. Maybe I’ll get lucky. Evidentially, even new Bearmach or whatever just don’t last more than a year or so.

I’m going to attempt one last time to check the starter itself today. I’m thinking I will go in and not just check the wires at the starter, but actually pull them apart and reset.

I have a lot to learn still, but unless one of you has a better idea now, I keep coming back to it must be the starter. (Secretly I’m glad I got a new battery anyway!)
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
A little progress.

This has been an intermittent problem that seems to come and go at random, or to get progressively worse, then stop all together. So this morning when the truck wouldn't start, I decided this is my chance to dig into the issue while the problem is actually happening. This is the first time I've been able to test while the problem was occurring, and as such, I think I found something.

I pulled the ignition wire from the relay off the solenoid and tested for voltage, and I got 12v when I turned the key to start. So then I put it back onto the solenoid and began looking to the other connections at the starter. So I touched the base of the spade connector with the meter probe, and this time I got no voltage. So I tried again with better lighting and at a better angle. No voltage. Then I pulled the wire off and unwrapped it to check for damage. Nothing seems out of place, but just a few minutes after I got that first positive result, I'm not getting any voltage at that ignition wire no matter what.

The relay behind the fuse panel does click on and off as expected, but is it possible that the relay is still bad, even if it is physically actuating? If so, is this a special relay, or could I open that panel and simply replace it with a matching type from NAPA?
 

DefendersNW

Well-known member
OK, but if I turn the key, then the relay clicks, and then the starter solenoid clicks, and the fuel pump runs and the instruments come on....?
Ignition switch (if Diesel) would have three or four positions -

4-pos for early diesels (NA & TD)
pos1 (off), pos2 (run), pos3 (glow), pos4 (start)

3-pos for late diesels (Tdi/td5)
pos1 (off), pos2 (run), pos3 (start)

SO if positions 1,2,3 work, it doesn't mean that position 4 will - and the intermittent or heat related inconsistency points at something that is a moving part...
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Figured it out!

OK, as I said, since the problem was actually happening, I was able to do trouble shooting. I found that the starter does work. There seems to be no problem with it. The relay does work. Battery is new, but I still got nothing at the wire end. This was baffling, and disconcerting, since that meant I was down to some bad/melted/broken wire deep in the harness....

Turns out, the V8 ignition wire was too short for the 300Tdi hook up. It was just a pig-tail hanging out of the harness. So two years ago, when I hooked that up, I had made an extension that was actually a few inches deep in the harness, right against the firewall, and it was all properly shielded and taped up--but it had come loose. That's it. Now I go and put everything back together....
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Ah, I see what you are saying about the ignition. I have what I think is a Td5 type of ignition switch. However, I was getting power to, and through the relay when in the start position, so that's when I ruled out the switch.

Anyway, it ended up being a waste of time since I had forgotten about the hidden spade connection, but I'm glad the mystery is solved. Especially since I'm going to Bend for a bit of a trail run on Monday!
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Not so!

I thought I had this sorted, but it popped up again! The other day, it seemed to pause again, before turning. I thought it was just in my mind, but now it won't start. So I went back to the same spot to check that ignition wire to the starter solenoid.

When I pull the wire off the solenoid, and test it, it shows a solid 12.6 volts when the key is turned to start.
When the wire is connected to the solenoid, I only get 7.2 volts at that terminal! And the solenoid DOES click!

Maybe I don't know enough about elektrickcity to know why the voltage drop is there when it is connected. If that is a normal thing to see, this is telling me that my starter is bad. But if that difference in voltage is not normal, I have no clue what is going on.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
How can I tell if it is shorting? (I would think that I'd be getting some spark or smoke from the location of the short when I'm holding the key in start. Also, why would it show solid 12v when not connected to the solenoid?)
How can I tell if the solenoid is bad, since it does actuate with voltage?
 
Last edited:

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
I'm thinking now that it has to be a bad solenoid.

I didn't think to do this earlier, because I could clearly hear the solenoid clicking. But when I put the meter onto the downstream side of the solenoid, and the starter fails to turn, there is no voltage at that spot. In other words, somehow the solenoid is clicking as if it is actuating, but it is not closing the bridge to let the voltage from the battery through.

All other points seem to be getting the voltage they need, when they are supposed to have it.

I tried to take the solenoid off of the starter I have in the garage, but I wasn't able to do it. So now I'm trying to remember why I even removed that old starter in the first place, because it does work when I jump it on a bench.
 

Napalm00

Well-known member
Wait starter or injection pump solenoid? My post was about the injection pump solenoid . Your cranking buy not starting right?

Or not cranking ?
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Not cranking. The starter solenoid does click, but I'm not getting any voltage on the other side of the solenoid when that happens. That is, the top stud has the main battery (and other) cables to it with 12v, the solenoid should close that gate, and the other stud should then also get 12v, thus firing the starter motor -- correct? Although the solenoid does make a click, when it does not fire off the starter, I can also see that there is not any voltage on that downstream stud.

The thing that is odd is that the starter I have in my garage is what I replaced with this current one. When I replaced it, I posted here about the problem, and my description seems to be the same...............
 

Napalm00

Well-known member
disregard my post then. I thought you were talking about the fuel stop solenoid. you may be inbetween teeth on the starter , put her in 5th or revers and push it a few inches. try again
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
That doesn't seem to make a difference. I've done the knock on, and I've done the rock, and it will still just start when it wants to start.

When I do this test, I ground one end of the multimeter, then pull the fuel solenoid wire, then turn the key to start:
  • If it spins the starter as normal, it will show about 8v on the downstream stud while spinning the motor.
  • If it does its thing, and doesn't start, then I get a click, but I get no voltage on the downstream stud.
  • Sometimes it will pause for 2-3 seconds, then suddenly I'll see voltage, and it will spin the starter like it should.
When I test on the upstream stud, there is always 12v, and all lines are in good condition.

When I test on the ignition wire to the solenoid, I get a consistent 12v when it is not hooked up, or about 7.4 volts when it is hooked up to the solenoid.

I think it must be a bad solenoid, and that when I fooled with the wire last time, I simply had the bad luck of knocking it loose, which resulted in me being fooled into thinking that the wire was my actual problem. The only other thing I can figure is that by having the start wire plugged into the solenoid, there is a problem that is causing low voltage to come through. However, since that low voltage has proven enough to spin the starter, and since I'm doing this with the battery connected to a charger, I still come back to the most probable scenario being a bad solenoid.
 

Napalm00

Well-known member
I don't even know if they sell that thing separate? Maybe buy the 3.1kw starter that Robert sells , I have one it's legit
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Right. It was just a thought, considering that I have a working one in the garage.

I’ll order a new starter, but I’m going to try one last thing tomorrow to make sure I’m not barking up the wrong tree again. I want one of his high speed starters, just would rather not spend the money if I don’t need to.

I’d appreciate any more thoughts from people based on what I’ve described.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
I ordered another starter from RD.

But 1/2 hour after doing so, I realized that it wasn't my starter all along. In fact, the starter I had in it two years ago wasn't the problem either.

After doing another round of tests, but doing it with an independent circuit -- one that does not go through the ignition -- I find that the starter/solenoid is working 100% of the time, and that it is turning the engine at least 2x as fast as when I use the key.

Boys and girls, I'm stupid.

I just realized that I dropped a total of $500 on a problem that wasn't the problem.

Anyway, now I have no clue what to do. Evidently the ignition wire is getting some kind of resistance. This means I need to tear down the bulk of the main wiring harness, and most of everything on the inside of the firewall. Which is something I don't have the time to do.
 

Napalm00

Well-known member
you only have to trace one wire, NBD. it goes from the engine harness to the multiplug near the fuel filer to the dash harness then to the ignition switch. its prob just the switch, they fail really often.
 
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