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5.3 on TH350. Starter jamming on flexplate

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Old 08-31-2017, 10:23 PM
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Default 5.3 on TH350. Starter jamming on flexplate

Having issues with turning the engine over. The starter is jamming in the flywheel and is staying engaged. I originally had a mini performance starter and I changed it to a remanufacture starter. Same issue with both starters. I think its the bolst on the flywheel bringing the flywheel closer to the starter and causing it to jam. The flywheel looks too close to the starter and the converter looks too far from the tranny.

I've attached a video link. Not much to see/hear already knowing the starter teeth is getting stuck.

required spacer is on. Not sure what lengths are on. I think they are stock bolt lengths.



























Old 09-03-2017, 10:36 AM
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Really hard to tell, but my guess is the spacer is on the wrong side of the flywheel. Iirc on a dished flexplate like you have the flexplate goes on the crank like stock, then the spacer goes between the flexplate and torque converter.
if not did you get the converter seated to the trans all the way? I believe its 3 clunks, that could make it screwy too

Ive always found its just easier to get a 6.0 4l80e flexplate with the spacer made on. Just my .02
Old 09-03-2017, 04:10 PM
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this is the way it needs to be. Flexplate bolted on with dish toward trans. Thin spacer to catch the torque converter hub. I wanna say looking at the pics u have it the correct way.

Your issue looks to be the starter. I don't think that is the correct starter for a ls engine. That looks like an older small block starter. the ls starter bolt pattern is straight across from each other. Not diagonal like most older small block starters. Check the starter first.
Old 09-03-2017, 08:19 PM
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I know this doesn't help but I have a friend with the same issue. 5.3L with a th350 and th400 both have the starter hanging up on the flywheel during cranking.

I will report back if he ever finds out why. He thinks it is a shimming issue although several attempts to re-shim have not helped.
Old 09-03-2017, 09:27 PM
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Good thing it didn't start, would have been instant death for the transmission pump. And that starter doesn't look like an ls starter. But to keep it from hanging up, shim the starter away from the flywheel. Most any parts store will have starter shims. Really shouldn't need to do that with ls stuff though.
Old 09-04-2017, 07:36 AM
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I have a 5.3 and the TH350. No problems here, using a Hughes Flexplate(Part# HP4004X) and the Hughes spacer when using a Vigilante 9.5" Torque converter, nor, when I switched to the current PTC TC which doesn't need the spacer(has a built in extended hub). On both setups, I had an original starter from either a stock Fbody Ls1 or a truck 5.3/4.8. That starter went bad a few months ago and I bought another from the local Advance Auto. For some reason, where the starter that I'd been using had 'staggered' (ie: two different length) bolts, this starter I purchased had symmetrical bolt lengths. And, when I cranked it, I squalled and stayed engaged for a second after it started. The sound was like a whistle. I knew what that was from old cars I used to own and just tried a few shims till it got the proper clearance. All is well now.
Old 09-04-2017, 08:46 AM
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Originally Posted by brandon6.0
this is the way it needs to be. Flexplate bolted on with dish toward trans. Thin spacer to catch the torque converter hub. I wanna say looking at the pics u have it the correct way.

Your issue looks to be the starter. I don't think that is the correct starter for a ls engine. That looks like an older small block starter. the ls starter bolt pattern is straight across from each other. Not diagonal like most older small block starters. Check the starter first.
Looking at it again brandon is right. My starter isnt staggered like that and the ls starters online arent either. I bet its engaging crooked and hanging it up
Old 09-04-2017, 04:23 PM
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Originally Posted by brandon6.0
this is the way it needs to be. Flexplate bolted on with dish toward trans. Thin spacer to catch the torque converter hub. I wanna say looking at the pics u have it the correct way.

Your issue looks to be the starter. I don't think that is the correct starter for a ls engine. That looks like an older small block starter. the ls starter bolt pattern is straight across from each other. Not diagonal like most older small block starters. Check the starter first.




I told the guy OEM starter I'll look it up....




When you say dish towards the started, you mean the flexplate is on how it should be originally? To be clear the flexplate dishes in towards the engine, its curving in not out. I never took the flexplate off when I got the engine.
Old 09-04-2017, 04:25 PM
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Originally Posted by kingtal0n
I know this doesn't help but I have a friend with the same issue. 5.3L with a th350 and th400 both have the starter hanging up on the flywheel during cranking.

I will report back if he ever finds out why. He thinks it is a shimming issue although several attempts to re-shim have not helped.


See if you can get pictures of his starter bolts lined up.


I've tried two starters, both had the same lineup.
Old 09-04-2017, 04:28 PM
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Originally Posted by Game ova
Good thing it didn't start, would have been instant death for the transmission pump. And that starter doesn't look like an ls starter. But to keep it from hanging up, shim the starter away from the flywheel. Most any parts store will have starter shims. Really shouldn't need to do that with ls stuff though.



I hope the pump isn't damaged. The engine was turning over but never started. I'll be unbolting the converter from the flexplate tonight to make sure its locked into the trans. I don't remember it coming out when I started bolting the converter to the flexplate. It looks like a lot of space in between there (converter and trans).
Old 09-04-2017, 04:35 PM
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Originally Posted by moe4541
I hope the pump isn't damaged. The engine was turning over but never started. I'll be unbolting the converter from the flexplate tonight to make sure its locked into the trans. I don't remember it coming out when I started bolting the converter to the flexplate. It looks like a lot of space in between there (converter and trans).
Good call. Just looking at the pic showing the distance between the converter and pump, there's no way the converter is locked into the pumps gear tangs.
Old 09-04-2017, 04:43 PM
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I looked up several ls starters they all look the same when it comes to the same size bolts.
Old 09-04-2017, 04:44 PM
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Originally Posted by Game ova
Good call. Just looking at the pic showing the distance between the converter and pump, there's no way the converter is locked into the pumps gear tangs.


If its not locked in, I'll probably have to spend that extra cash to have a trans shop open it up to look. I don't mess with transmissions at all!
Old 09-04-2017, 05:25 PM
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when I say dish I mean the flexplate should curve out toward the transmission side. I wanna say the flexplate will not bolt up to engine the other way around. IF u left the flexplate on the engine the way it was factory it is installed be the correct way. THIN the spacer goes on after the flexplate to engage the converter hub.

If u would have used a 4l80e flat flexplate u would install it with the spacer first thin the flexplate. They are installed completely different from each other.

Did u hog out the original converter holes in the flexplate for the converter to bolt up? are u certain that that converter is the correct one for that trans? converter should install close enough to the front pump that u cant fit your fingers behind it. Or should u barely be able to see the hub or front pump seal. Looking at the pics u have a lot of room between there. What brand converter?

But as far as your starter problems just go to the junk yard and grab a used starter and install it and be done. The aftermarket parts store starters are junk these days. The original used ls starters are really tough and rarely go out.
Old 09-04-2017, 05:33 PM
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Originally Posted by moe4541
If its not locked in, I'll probably have to spend that extra cash to have a trans shop open it up to look. I don't mess with transmissions at all!
The pump is easily serviced/changed by even a complete novice, should you even need to. Even if you TRIED to screw up changing the pump....i don't think you would succeed.
Old 09-05-2017, 09:57 AM
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Update.....I removed the converter from the flexplate. There's a good amount of space in between the two once the bolts were taken off. I was able to push the converter into the trans, one click so I guess it was pulled out when it was bolted to the flexplate.

I'm not sure if there's damage to the pump with just turning the engine over while it was a click out.

I tried turning the engine while the converter wasn't connected......the starter still jammed up.










Old 09-05-2017, 03:29 PM
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ok yea that is not the correct starter. Change it before u break the mounting flange on the block or trans.

take and add some washers between the flexplate and converter. A lot of aftermarket converters need shimming to be installed correctly. I wanna say u need 1/4" gap. IF its anything more than that add washers to get the correct gap. I usually use a drill bit to measure with.
Old 09-05-2017, 07:58 PM
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Originally Posted by brandon6.0
ok yea that is not the correct starter. Change it before u break the mounting flange on the block or trans.

take and add some washers between the flexplate and converter. A lot of aftermarket converters need shimming to be installed correctly. I wanna say u need 1/4" gap. IF its anything more than that add washers to get the correct gap. I usually use a drill bit to measure with.
Ok thanks! I'll go to a salvage yard in the morning for a starter.
Old 09-05-2017, 08:02 PM
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Here's my build. First time working with a LS and turbos. This site encouraged me to try it! Hopefully I'll have it running in the next day or so.



83 Shortbed dropped 5/7



2002 5.3, LS1 instake, lots of upgraded parts, twin 68/70s

Old 09-07-2017, 09:57 AM
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Ok after three starters and shimming all of them, the start still jams. Even the OEM. Only thing I can think of is the flexplate is bad. I did have one guy tell at local shop say the flexplate was backwards. I don't see how that's possible, the dish is going towards the engine, going in. Unless I'm wrong. I never removed the flexplate from engine when I got it.

The teeth on the flexplate are good.

Last edited by moe4541; 09-07-2017 at 01:25 PM.


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