I have a 2004 f250 6lt diesel. Ran great, went to my son's house to move some junk, parked it. Then started it to back into his garage, started fine. Shut it off, 5 mins later went to start it, turned over as normal about two times, then the starter slowed right down, turning over the engine at a crawl. Did not start. I've since cleaned all contacts, including grounds to vehicle - no effect. Charged batteries, no change. I then figured it was starter, so I replaced it, turned over a little faster but not fast enough to start truck. I replaced one battery with new, no change. I have two batteries in truck, so in case one was bad, I tried to start with both new and each, then with jumper cables, all three. Also used a boost from another vehicle. Still turns too slow. The fuel seems to be being supplied, though I don't have a pressure gauge - full iin the secondary filter, plus I drained at the water separator, turned key, then opened plug and water separator was full of full again. Any suggestions?

 

What about the battery cables ? If corroded internally , will never allow current required for starting to pass through.

 

ok, I will have a look into that.Can I run a jumper right from battery to starter post, can't remember if the main lead is always hot, ie will I still need to turn key to energize the first stage?

 

If the positive cable from the battery goes to a solenoid and the solenoid passes the current to the starter,then you can connect the positive jumper wire to the same terminal that the battery positive connects to.
If you connect the jumper cable directly to the starter hot terminal the starter will operate.
Some starters have the solenoid attached right on the starter itself. It is pretty difficult yo try to connect a jumper to the battery cable connection down there.
If you can , however, manage to get the jumper connected to the terminal on the starter solenoid that comes from the battery positive terminal, you will have by-passed the cable and if it operates properly that would confirm a battery cable problem. It is much easier to do a voltage drop test on the cables and connections while attempting to start the engine. You have to load the cables to do the voltage drop test correctly.

 

ok, I follow you. I'd love to run out and do it right now, damn thing is 50 miles from here! I'll give it a try tomorrow, let you know how it makes out, hope you're right, I could use a break, already replaced oil pan, egr cooler, and differential cover this year, not to mention the battery and starter.

 

A quick visual you can try would be to put the headlights on and attempt to start the truck. If the headlights go dim there is an electrical supply problem .
If the lights stay bright and the engine is slow turning over would indicate a problem in the supply to the starter, or the starter itself .

 

Well I by-passed the cable to the starter from the battery, no change. The lights do go dim on each revolution, and the voltage drop was down to about 9.5 - 10 volts. I also hooked up a ground from battery to frame, just in case it was a bad cable to ground.

I wouldn't think its the starter, as I replaced the old one, and with the new one, it did turn over a little quicker - but just not enough.

I was wondering, if something had seized, for instance, anything connected to the drive belt, could that cause enough resistance?

Any other suggestions would be, and are, appreciated.

 

hello again, you had proided me with advice on my original problem, turns out that the a/c compressor had seized, and the starter couldn't turn over the engine fast enough to start it up. I removed the drive belt and it started up right away.

I have the tech manual covering my 2004 f250 6.0l, but its not very clear on removing the cooling fan - so I thought perhaps you may know, is the fan on but reverse threading? And does one need the special tool to remove the fan or is their another option? Any advice would be appreciated.

 

Fan nut is RH thread, it does require a specialized wrench but you could probably improvise.

If the compressor failed internally and loaded the system with debris/trash it will need to be flushed and a core orifice and new accumulator.. If you want to have a go at the compressor replacement I can send you a few docs for the repair..

 

thanks, and yes, pls send me material on compressor replacement, much appreciated