Engine Starter Gear Chewed Up

Cafors · Jun 1, 2021

Hi all, I've been fixing up a '90 LX 302 and have been having issues with starters. The starter gear is getting chewed up and worn down over time (see picture), is very loud to start, and makes a very loud metal grinding noise when the car starts. I'm on my second starter now, which I bought used from an autowrecker, and the same problem is happening. Flywheel looks fine to my eyes... Any ideas on what my problem might be?
Thanks in advance!

HemiRick · Jun 1, 2021

I had the same problem w reman parts store carquest starters finally the 3rd one worked and has worked fine....I bought a flywheel thinking mine was f'ed up but when I looked it was fine....so just kept replacing starters.

Rdub6 · Jun 1, 2021

The first cheap starter I bought would not even fit right against the alignment plate without me grinding some metal off the starter. It was a Ford plate, so I assumed that was in spec.
Cheap parts are just that....... cheap!

7991LXnSHO · Jun 1, 2021

Chevy starters usually come with shims. That does not mean Fords have perfect gear clearance. The shims are available in the Help (Motormite) section or catalog. What the gear clearance spec is, I have forgotten, but I bet it is your problem.

slow84lx · Jun 1, 2021

Does fixing up mean that this combination was just put together? Or, was someone elses project that you just picked up and started trying to get it to run again?

Does your car have the shim plate in place between the engine & transmission?

Are you certain that it has the correct flywheel? It seems to look like the flywheel tooth count is incorrect and causing a mismatch.

Cafors · Jun 2, 2021

slow84lx said:
Does fixing up mean that this combination was just put together? Or, was someone elses project that you just picked up and started trying to get it to run again?

Does your car have the shim plate in place between the engine & transmission?

Are you certain that it has the correct flywheel? It seems to look like the flywheel tooth count is incorrect and causing a mismatch.

This is a family car that has been sitting for the last 5 years, and I've been trying to get it back into shape
It does have the shim plate installed, I did the clutch on it before I started driving it, (starter still had this problem before I replaced the clutch)
The flywheel should be the correct one... It was surfaced on the last clutch install (before mine) and looked fine to my eyes and wasn't warped the best I could tell.
Thanks for your reply!

Cafors · Jun 2, 2021

7991LXnSHO said:
Chevy starters usually come with shims. That does not mean Fords have perfect gear clearance. The shims are available in the Help (Motormite) section or catalog. What the gear clearance spec is, I have forgotten, but I bet it is your problem.

Thank you! I'll look into gear clearance and shimming it, that sounds like it might be the problem. I read a passing post on a forum that said that the starter gears for vans and trucks were longer at the time, and the first starter I had on there was from an '89 Bronco and then this one I got from an auto wrecker was off of "a van" quote them....

Cafors · Jun 2, 2021

HemiRick said:
I had the same problem w reman parts store carquest starters finally the 3rd one worked and has worked fine....I bought a flywheel thinking mine was f'ed up but when I looked it was fine....so just kept replacing starters.

I hope it doesn't come to this hahah... Starters are expensive and I'll probably need a new one as it is!

HemiRick · Jun 2, 2021

lifetime warranty so even though it took 3 only had to pay for one....

7991LXnSHO · Jun 2, 2021

If the starter and flywheel are for different number of teeth, will they even engage? I figure the flywheel is a different diameter with the different tooth count, although I never measured both.

Mustang5L5 · Jun 2, 2021

Electronics can also play a role here. The when you send power to the starter it's doing two things. Spinning the motor, and engaging the pinion. A weak connection can cause both to not be as efficient as possible. I would double check your connections and wire quality leading back up the starter relay.

slow84lx · Jun 2, 2021

Cafors said:
Thank you! I'll look into gear clearance and shimming it, that sounds like it might be the problem. I read a passing post on a forum that said that the starter gears for vans and trucks were longer at the time, and the first starter I had on there was from an '89 Bronco and then this one I got from an auto wrecker was off of "a van" quote them....

And there may be the whole problem. Mustangs use a different size / tooth count flywheel than a truck/van and the starters are specific to the flywheel. Make sure that you get a starter that is made to fit into a Mustang. I'm not sure what other cars will work for the application but avoid a starter from any truck/van.

Don't shim your starter. Get the right one first. Yes, a Ford starter can be shimmed but very few will require it.

Cafors · Jun 3, 2021

I went ahead and shimmed the starter this afternoon just to see how it would be before running out and spending $100 on a remanufactured one, and it sounds MUCH better already. I also called a few Ford dealerships looking for the part number for the specific starter for the car, and none of them could give it to me. I'll pick up a starter from rockauto soon, but in the meantime shimming seems to have worked great. I'll keep you guys posted! Thanks everyone for the help!

dcm0123 · Jun 5, 2021

I had better luck with OEM junk yard starters and alternators. If you go to the junk yard, you want to make sure you get an OEM original, not rebuilt by a 3'rd party or aftermarket.

The drive a one way clutch (See attachment). You should be able to rotate the gear one way without spinning the shaft and the other way it will spin the shaft. If it does not rotate free one way, when the engine catches, the flywheel will spin the starter faster which is why there is a noise after you let up on the key. The drives are easy to replace and inexpensive but I would only use Motorcraft brand drives.

On GM engines you add shims to add clearance between the gear and flywheel. The shims control the gap between the two gears when the drive is fully engaged. This is because the shim goes between the engine block and starter.

On my Ford the shim would go between the starter and transmission which will only control the how far the starter gears overlaps the flywheel, not the gap between the gears. If the starter gear is engaging to far you may see scratch marks on the one way clutch hub on the shaft next to the gear and there may be addional noise. If you are missing the plate between the engine and transmission you may need to add a spacer to control the depth.

More Information for STANDARD MOTOR PRODUCTS SDN3A

Cafors · Jun 14, 2021

Hi all, thought I'd write an update as I sat here under the car fighting the starter.
I ordered a new starter and it worked like a charm for about the first 3 starts. After that, back to the grinding noise that I get when the engine starts. I decided to try shimming it back to see if that would make a difference, and sadly it does not. I thought I'd paint the starter gear to see where it comes in contact with the flywheel, just to see what happens when I shim it back, and it looks like it's barely grabbing any of the flywheel teeth (as expected). All of the electrical looks good to my eyes. Does anyone have any ideas of what it could be? Or is it time to order a new flywheel? If anyone knows the size of tranny plug I'll need that would be great as well.

HemiRick · Jun 15, 2021

It took me 2 or 3 Cardone rebuilds before I got one that worked right.

Boostedpimp · Jun 15, 2021

how does the teeth on the flywheel look?

dcm0123 · Jun 15, 2021

Looking at Summit Racing they make 157 and 164 tooth flywheels which fit the small block Ford Windsor 5.0 engines.
Looking at the SBF racing bell housings many are dedicated to 157 or 164 tooth flywheels.
With the 164 tooth larger diameter flywheel the starter gear has to be positioned further away from the crank shaft to engage the flywheel properly.

A stock 90 Mustang takes a 157 tooth flywheel. Do you have a stock engine and transmission set up?

As noted in the previous post, look at the teeth on the flywheel. They maybe damaged or missing.

If flywheel is OK count the teeth on your flywheel next and confirm what your bell housing is designed for.

dcm0123 · Jun 15, 2021

Looking at the tooth pattern on your new starter you are not getting enough engagement. The pattern on the original starter looked good. Did you insert a spacer between the starter and the bell housing? If not, I would return the starter. I doubt this is causing your grinding problem but it is not good for the life of the starter or flywheel.

Cafors · Jun 15, 2021

dcm0123 said:
Looking at the tooth pattern on your new starter you are not getting enough engagement. The pattern on the original starter looked good. Did you insert a spacer between the starter and the bell housing? If not, I would return the starter. I doubt this is causing your grinding problem but it is not good for the life of the starter or flywheel.

Yes, the paint marking was with the starter shimmed out, it should be getting more engagement
The flywheel teeth don't look the best, and its chewed up in some places, so I'll be ordering one and putting it on regardless, would be nice to stop the rear main seal leak while I'm in there anyway...
The engine, tranny, and flywheel have not been replaced so they are all stock.
Thank you all, I will update once I get the new flywheel on!

Engine Starter Gear Chewed Up

Cafors

New Member

HemiRick

I'd be looking at jacking under the house

Rdub6

So while I wait to figure out my rear end issues

7991LXnSHO

wanna catch the space herp

slow84lx

clean it good before insertion

Cafors

New Member

Cafors

New Member

Cafors

New Member

HemiRick

I'd be looking at jacking under the house

7991LXnSHO

wanna catch the space herp

Mustang5L5

That is…until I whipped out my Bissell

slow84lx

clean it good before insertion

Cafors

New Member

dcm0123

Cafors

New Member

Attachments

HemiRick

I'd be looking at jacking under the house

Boostedpimp

dcm0123

dcm0123

Cafors

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Engine Starter Gear Chewed Up

New Member

I'd be looking at jacking under the house

So while I wait to figure out my rear end issues

wanna catch the space herp

clean it good before insertion

New Member

New Member

New Member

I'd be looking at jacking under the house

wanna catch the space herp

That is…until I whipped out my Bissell

clean it good before insertion

New Member

New Member

Attachments

I'd be looking at jacking under the house

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