I have installed (some have been put on by others) 6 starters on this truck (highboy w dump bed, 4wd manual) since purchasing it about 3 years ago. Have really only gotten about 6 months of good use out of it because the starters all seem to get the bendix gear 'chewed up' and the top half (the leading end going into the flywheel) becomes ground away into a Christmas tree type shape.

VIN says this truck came with a 400. When purchased, the prior owner (didn't know any history on the truck) said it has a 351m. Both motors take the same starter, which are all grinding up to useless in (at best) about 20 - 50 starts. I've checked the flywheel (180 teeth) as well as had it checked by a professional garage, which installed starter number 5, and we both agree flywheel is not warped nor the ring gear damaged to be causing the problem. Carquest (parts store) even tried to see if starter for 300/6 cyl or the 302 would be suitable (that's why the tooth count) but those starters won't bolt up, and the gear on bendix is identical to the 400 starter. Orig shim on bell housing is still intact, and I have also tried with 1 shim on top of this. This last starter w/1 shim ground up before I could get the truck off the drive. Unfortunately, when I traded out the first starter (which died a natural death after the first year) I used it as a core and don't have it to compare to subsequent starters. What's going on? What now? Otherwise, a wonderful truck. Thanks for your help. (Compression when turning motor by hand seems about normal - I'm able to turn w one hand while counting flywheel teeth with the other - not a job I care to repeat in 30 degree weather (smiles)).

 

This is what you need to do.
I believe you have the older poleshoe type starter.
There is a way to get the drive to engage the flywheel, but not crank the engine, I just don't remember how we did it.
Any way, with the starter mounted , manually turn the drive (bendix) to engage the flywheel and be prepared to place something in between the drive and housing to keep the drive from retracting back to it's normal position.
Now you can check the fit and maximum travel of the drive into the flywheel. You should be able to see what , if anything, is wrong with the travel and the fit of the drive gear and the flywheel.
I'm sorry to say , but the junk that we are getting from outside the country that the rebuilders are using to make a buck is causing so much grief these days. If you haven't tried a rebuilt starter from a Ford dealer, then it may be time to do that.
Also, check and make sure you have none of the spark plug wires in the firing order running parallel to one another. For example, if the firing order was 1,5,4,2,6,3,7,8 you would want to keep wires 7 & 8 from running next to one another. That is to prevent an induction crossfire.
I also believe that there is a difference with the nose end of the starter .
An automatic trans starter is different from a manual trans starter. If you do the above checks you should be able to find the problem then know what you need to do to correct it Let us know if any of this was helpful.

 

Hello Hanky - I'll give this a try and thanks for the quick response.

Also, after reading some more overnight around the internet, I have seen some issues where the starter wire (through age/manhandling) has weakened or the starter solenoid is not allowing enough power through to fully engage the bendix gear. What do you think of that? If I volt test past each of these items, how much voltage needs to make it through to fully extend the typical starter?

Also, to try your test, how would I get into the point where the flywheel/starter gear connect? I understand what you're saying but unsure how to proceed.

And I definitely understand about the foreign reconditioned starters. I have tried starters from different auto parts stores, but still have not tried a Ford rebuilt one yet.

Thanks, Susan.

 

Before you attempt this , REMOVE THE NEGATIVE BATTERY CABLE ! When the key is turned to the start position the strong magnetic field pulls the large hunk of iron down and that moves the fork that moves the drive gear into the flywheel.
You can do the same thing manually by sticking a large screwdriver behind the drive roller housing and index the drive gear with the flywheel. TO DO THIS, you MUST remove the negative battery cable or you might engage the starter motor.
I have no desire to poo poo our local generator / alternator shops because they usually do a good rebuilding job. If they can't obtain quality parts to work with they know you will be back and that doesn't help their business. When ever possible I either had a local rebuilder rebuild the starter or purchased a rebuilt one from a dealership. Not all mass rebuilders are questionable , just most of them. I have seen where a local rebuilder will replace every part that wears. Some of the mass rebuilders will reuse a part because it doesn't look that bad. That's how they save.

 

I'm still fighting this starter alignment issue.

I cannot figure out how to visually check the alignment of the starter bendix w the flywheel - cannot take off bell housing because the starter body mounts to the housing. Nowhere to visually see the whole works (starter/flywheel) engaged.

I found elsewhere on internet how to extend bendix gear without 'running' starter - they suggested using jump wire to go around solenoid directly to starter - this would throw out bendix, but not run the motor or spin the gear. Haven't tried that yet - no purpose to if I cannot see what the result is.

I took starter apart - aligned the gear teeth with the flywheel - I am now certain that I have correct starter (9 tooth for the 180 tooth flywheel) - they mesh beautifully when I hold the teeth together and run around the flywheel.

It appears I have an alignment problem.

My issue at the beginning of this thread was that the starter gear didn't appear to engage fully because of the grinding noise and this was wearing down the starter teeth at the 'nose end' of the gear into a christmas tree type shape.

I am shimming (blindly) on different attempts and am either hearing a 'whirring' noise with nothing touching or a horrible grinding noise as if I'm going too much the other way. However, it appears now that the 'wear' from the grinding noise is occurring dead center on the teeth of the gears, (as opposed to on the 'nose end' as previously posted), so I'm making some progress.

I'm taking a break now to recharge battery (and self) but my next shimming attempt will be on the 'inside' (right) edge of the starter trying to tilt the bendix gear slightly back into the flywheel teeth. Hopefully I'm close, but would much rather be able to align things visually once and for all instead of all of this trial and error work. Any help is appreciated.

 

Same problem on a '81 Bronco 351W. Replaced flywheel but problem started again within a few months. Have tried an 1/8" spacer shim from NAPA and starting is very smooth and quiet for a few starts but gets noisy again quickly and end of bendix gets chewed up (7 starters in 3 years). Impossible to see alignment because factory aluminum locator/mounting plate blocks view. It is puckered in so using the Napa shim provides an accurate (hopefully) locator hole. Last starter only lasted one month. Has anyone solved this problem? Guess I'll try a Ford factory starter before selling the truck.

 

I know this is a 2 month old post but decided to reply to this very common problem that people don't understand. Almost all starter Motor cables are undersized from the factory since they don't size them for the in-rush current required to crank your engine, to most this is a waste of time. But in the end it shortens the life of your starter motor, causes it to run hot when it cranks. Usually doesn't prevent full engagement of bendix to flywheel but suppose it could. In my experience I usually just see starters burn up early due to the fact that they are running hot.

Voltage drop for DC circuits: CM= K x I x L / E

Cm= Circular mill area of cable
K = 10.75 (constant Resistance of copper)
I = Load current in Amps
L = Length of conductor from power source (battery) and back in FEET.
E = maximum voltage drop at load in volts (eg: 3% voltage drop on 12 volt circuit is 0.03 x 12 = 0.36) 3% is what I use for starter motors 10% drop is common for lights and other non essential components)

( K )is constant
( I ) must be found either from a spec book on the starter stating its normal load amp draw or by putting an amp meter on motor when u crank it under normal condition ( meaning its trying to start your car/truck) make sure your connections are good and clean if your cable is undersized your amp reading will be high but it doesn't matter because then you will just oversize your cable which is never bad
( L ) Length of conductor is most common mistake you have to determine not just the distance of positive cable from battery to starter but the distance of the ground circuit to get amps back to battery don't forget formula is in feet not inches. (easiest thing to do is double the length of the positive cable and use that as your length number. I actually put a ground cable same size as positive cable from one of the mounting bolts on starter back to ground on battery. that way all those amps aren't trying to go through the engine block, frame, crappy rusted ground cable etc..
( E ) can either be 0.36 for 3% drop or 1.2 for 10% drop (use 3% for starters)

After all this crap you will then conclude the required CM area of your cable. At which point you will then have to go and find a Cm chart. Ill include a couple numbers common to starters for you here that you can use.
4AWG = 41,740 CM
2AWG = 66,360 CM
1AWG = 83,690 CM
0AWG (refered to as one "aught") = 105,600
00AWG ( Two "aught") = 133,100
000AWG = 167,800
0000AWG = 211,600

This was a common problem on starter motors from the 90's specially ford truck engines with 351 V-8s everyone will tell you "I have to put a new starter in that truck every year" or as I did with mine put the right cables in it once. 4 years later same starter motor was still working.

And now if you don't want to do all that math and figuring just get a 0AWG ("one aught") cable for the positive and one for the negative, (which you will bolt from the mounting bolt on starter to the negative terminal on battery) you cant buy these cables so you usually have to make them. I almost guarantee if you go to an auto parts store every battery cable there will be 4awg in my opinion to small for almost any engine, (but you can double up smaller cables to gain the CM you need for your application reason its not recommended is because its harder to get 2 terminals on same bolt) but a 0AWG cable is plenty for any starter motor on a ford truck. only time i've had to go with more is when i'm cranking over a big cat 3160 diesel or some other monster engine, with a 60lb starter motor.

Reading all this may be a headache but you can apply that same formula to any DC circuit that your working on to figure out which size cable you should be running.

 

Good info tjc.
Don't forget about the primary relay on the firewall / sheet metal. A good place to check voltage drop too!

 

Thanks for your info - questions -

My calculation is coming up 229k which would require 0000awg cable size. Obviously I am doing something wrong - Your cable connector length - is it in empirical inches? or metric cms, which would make my answer even greater -

Amp draw - my starter no-load draw is 80 amps, but the book of specs says that 'lock test' should draw 670amps.

Starter cable length from solenoid is 48" *2 = 96"

Lastly, should your 3% read .036 instead of .36 (30%)?


I switched my cable to a #2 awg as a regular update - Would like to get to the bottom of understanding your formula because I can use it in other areas as well as on this vehicle. Additionally, I will probably add return wire to battery as you are suggesting to improve the circuit.

Re my specific starter issue as originally mentioned, I have at least temporarily solved my issue by putting a bushing in the bottom starter hole before inserting the mounting bolt to keep the starter engaged with the flywheel when it is powered up. My original issue was that the lower bolt hole was too big allowing the flywheel to push the starter back instead of the starter sticking in the correct line to turn over the engine. I've had about 120 perfect starts to date. More than I've had on the previous 5 starters, that's for sure.

Thanks to you and Hanky for your help - I hope to hear your explanation of the formula specifics.

 

Yes red-head that was my fault I forgot a very important piece of information, the length is in FEET. I have gone back and edited my original post to show that.

Also The 80 amp number is as it says "no-load" so you wont want to use that for calculation, you also don't need to use "lock test" what that is referring to is how many amps the starter will pull if you jam something in it so it wont turn, then give it voltage. reason for this number is usually to give electrical techs or engineers the info they need to design an electrical system so nothing catches on fire.

Normal load test I would bet your starter pulls 200-300 amps when cranking. Depends on viscosity of Oil, weather its cold or warm, compression in cylinders, weather its automatic tranny or manual. All those things affect how easily or hard your engine turns over, the harder it turns the more amps the starter will draw.

If you do a CM calculation with no load amps you get something around a 6AWG wire so manufactures up that to a 4AWG wire and call it good, ya when all the battery terminals are brand new the engine oil is warm new and clean, the frame has no rust anywhere so the "common" ground through the engine block, bolts, little wires here and there are all good conductors at this point, soon as things start to rust, "common" ground not so good anymore, its -30F in February oil is thick cold doesn't flow well, you start pulling a lot more amps


You do the calculation for your vehicle with 200-300 amps you come up with either a 1AWG or 2AWG wire thats why I stated if people don't want to figure the math just use OAWG

Your 2AWG wire that you put in is probably the right wire using the info you gave me assuming average amp draw of 200amp and using 9' (I added a foot to your info since you said "from the solenoid" solenoid is just a switch, the amps come from battery, if its a fender mounted ford solenoid its about 6-12" from battery) you get 53,750CM. Looking at my chart that makes 4awg to small, 2awg just right. but if you push those numbers a bit to say 300amp draw you end up at 1AWG.

Hope this helps and feel free to ask any more questions, hopefully i didn't miss something this time