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Hey guys, i need to bench test the starter in a 1981 F100, auto , 302.
As you know, the solenoid is on the fender well. There is one post on the starter. Do I use jumper cables from the solenoid posts to the starter to test?
There is only one post on the starter which is negative from solenoid.
I believe the issue is the teeth appear to be ground down. Which is not allowing the truck to start.
I dont knnow what you are looking for by "bench testing" as the starter is not under a load and should spin if not totally junk.
That looks to be a high TQ because the power lug is on the end of the starter.
But here goes.
Hook 1 lead of jumper cables to that lug at the rear of the starter and the other end to the battery POS +
The other cable get hooked to the starter body, like where the bolts are as that is the ground for the starter, other end goes to the battery NEG -
Now as soon as you have all the cables connected the starter will kick and flop all over the place.
I would make the connections at the starter, hook the POS at the battery, then stand on the starter and then hook the last cable to the NEG of the battery and the starter should kick and spin.
Dave ----
Take your finger and try to turn the little gear on the starter. Turn it one way and then the other. It should spin free one way, but not the other. There is a one way clutch in there that can go bad.
That looks to be a high TQ because the power lug is on the end of the starter.
Dave,
I'm pretty sure that is a standard Ford "Positive Engagement" starter. Note the angled cover on the side of the main body. At this link, the first two pics show the difference:
Here's another image of the stock starter with the angled cover and a single electrical connection on the end of the main body. The image is blatantly stolen from RockAuto. Note how it looks similar to his:
For reference, a high torque starter. Note the smaller cylindrical solenoid parallel to the main body. Electrical connections are on the solenoid, not the main body:
I believe the issue is the teeth appear to be ground down. Which is not allowing the truck to start.
Hi Jeff,
I've seen teeth a lot worse than that and the starter still works just fine. What happens exactly when you say the truck won't start? Does the starter just spin and maybe grind, without actually turning the crankshaft? For a starter to work properly, it needs to snap up to speed very quickly to kick out the gear to engage the ring gear on the flywheel. Lots of different faults in the system can cause slow/poor spinup of the starter, but the poor starter itself unfairly gets the brunt of the blame.
I'm no fan of the bench test. Unless the starter is totally dead, it will pass. The whole process doesn't hurt anything, but it can be a waste of time and can give you a false positive that a marginal starter is good. You can read my over-inflated opinion here, post #17, including details of a VERY effective bench test apparatus already sitting in your driveway or garage:
Thank you guys! I always appreciate the quick intelligent replies. I did think of taking it to the auto store as suggested. I wanted to give it a try first.
the real issue sounded like grinding almost like teeth of starter were not aligned with flywheel ring gear.
I'm wondering how your solenoid, battery and cables are? Not having proper voltage and current can make the starter a bit timid about responding to your command, creating a weak meshing of starter to flywheel. When you hear the starter gear grinding and not meshing with the flywheel teeth it's loud and distinct. Owie! Let go a dat key right now! The starter motor itself can growl pretty loud when not being fed the proper diet of electrons. Karl, AKA Voltage Drop Man, will be round shortly with a link to his testing procedure.
Voltage Drop Man, will be round shortly with a link to his testing procedure...
Everybody's favorite superhero has been waiting in the wings since post #5 above, after asking for more details about exactly what happens when the engine "won't start". Still waiting, hint, hint...
If the starter is not spinning up rapidly as designed, here's the link anyway:
Thank you guys! I always appreciate the quick intelligent replies. I did think of taking it to the auto store as suggested. I wanted to give it a try first.
the real issue sounded like grinding almost like teeth of starter were not aligned with flywheel ring gear.
thanks, Jeff
That clutch in the bendix going bad sounds the same. If you wanted to throw a part at it, you could buy a new bendix (gear assembly). If you can even get them anymore? I did a search and it seems they sell them for oddball stuff like 8N tractors and Model T's, but you might have to buy another starter to get one for a modern vehicle.
Hey Dave, I followed your advice to test if the starter is working. The starter does kick out and spin. However, one of the other replies (don’t recall his name) said the starter gear should spin one way but not the other. This one spins both ways just by fingers.
what, if anything , does this suggest?
Thanks,
Jeff
Originally Posted by FuzzFace2
I dont knnow what you are looking for by "bench testing" as the starter is not under a load and should spin if not totally junk.
That looks to be a high TQ because the power lug is on the end of the starter.
But here goes.
Hook 1 lead of jumper cables to that lug at the rear of the starter and the other end to the battery POS +
The other cable get hooked to the starter body, like where the bolts are as that is the ground for the starter, other end goes to the battery NEG -
Now as soon as you have all the cables connected the starter will kick and flop all over the place.
I would make the connections at the starter, hook the POS at the battery, then stand on the starter and then hook the last cable to the NEG of the battery and the starter should kick and spin.
Dave ----
Hey Dave, I followed your advice to test if the starter is working. The starter does kick out and spin. However, one of the other replies (don’t recall his name) said the starter gear should spin one way but not the other. This one spins both ways just by fingers.
what, if anything , does this suggest?
Thanks,
Jeff
If the gear spins both ways, the starter motor can't turn the engine. So there is your problem, the starter gear or what's commonly known as the bendix. If you have a automotive electric shop in your town that rebuilds starters and alternators, they can probably get you the bendix. They could also install it for you and go over the complete starter. Or you can take the starter to the auto parts store and buy a reman one. Be prepared to go back several times. It's very difficult to get a reman starter that actually works.
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