Starter Questions

[dcpppf]

For starters (pun intended) some background is that i recently did a transmission swap on my 2.9L from auto to manual. In doing the swap I installed the 4.0 clutch FW and starter.

I threw in an old 4.0 starter that was free and upon starting it would sound like it was grinding really bad AFTER the engine started. for just a couple of seconds then whisper quiet. I finally got around to buying a new starter to see if that would fix the issue, and last night I got it put in. It is about 95% more quiet (can barely hear it) but there is still that sound for just a couple of seconds. I think it is just the engine/FW turning the bendix and the sound is just a ratcheting sound (not necessarily a grind like i originally thought).

So for some reason I just think the bendix isn't retracting quickly and is being held out for some reason. The only reason I can think of is because the 4.0 starter has the starter solenoid integrated in to the starter. And to avoid re-running wire I just "daisy chained" the two solenoids. See doodle below. So basically i just have the batt + and starter signal at the 4.0 starter jumpered together. Thoughts on if this could be causing the solenoid to stay energized an extra couple of seconds after the key is put back in the run position?

The other question I have is in regards to a slow crank. The truck starts fine/quick while cold. But after restarting it with a hot engine it has to crank 5-10 seconds before it'll catch and start. Seems to be dependent on temp or humidity. The longest it ever cranked was a night when it was raining. It always starts... just has to crank an abnormally long amount of time sometimes.

 

[RonD]

Warm cables have higher resistance, as does warm starter motor
So when starting warm engine there will be a bigger voltage drop and maybe slower cranking speed

You may want to use larger gauge(or just new) cable from battery positive to starter relay and then from starter relay to starter motor
This will lessen the voltage drop, less resistance, which by default increases the Spark Voltage


You can run the "low current lead" down to the 4.0l Starter motors "S" post(remove jumper), by-passing the fender mounted starter relay
Then move the starter motor's "fat cable" at starter relay over to same post as Battery positive cable

So fender mounted starter relay is just the 12v power distribution post, not used for starter motor

You can buy later model Battery positive cable that has the longer "fat cable" that runs directly to starter motor and then another larger but not "fat cable" that runs to fender mounted starter relay post, its still the 12volt distribution point
You would need to hook "low current" wire directly to starter motor's "S" post with this conversion


As for the slow release of starter gear, not to sure on that one
I think the Block Plate on the 2.9l and 4.0l were the same on manual trans, but auto may have been different
Block plate is there to align starter motor with ring gear
The bolts and bolt holes in starter motor have too much play to "just be aligned" by tightening

You may be able to shim, thin washer on one bolt between starter and bellhousing, to off set starter enough so gear doesn't hang up
just guessing here

 

[dcpppf]

Hmm thanks for the reminder on the higher resistance possibly coming from a warmer cable. I guess that would just surprise me to be the cause since it was fine with the 2.9L starter. BUT... it is a much beefier starter so could be pickier.

I actually have a new jumper from the batt + to the fender solenoid on the way. Will have to get under there and see if that low voltage signal wire can stretch down to the starter or not but I'm going to be it doesn't. Either way maybe pulling one of those two solenoids out of the circuit will do the trick... I may also just try to move the one wire on the starter motor over to the other post so it doesn't "pass thru" the 2nd solenoid.

Either way appreciate the thought there. Makes it easier for me to keep driven to looking in to it lol.

 

[RonD]

Have to remove "jumper" on starter motor to if you give starter motor direct connection to Battery Positive
And so you would also have to run low current wire to starter motor "S" post at that time