# Starter engaging while in reverse?



## Kevin123! (Oct 27, 2020)

Hello all, I've been searching around for the fix to this problem for a bit. But haven't seem to find an answer that works for me yet. Quick overview of vehicle. Customer that I painted car for died and a friend of mine bought it. The original owner had motor build up pretty well. (Built 6 years ago and never came with proper build sheet as engine builder is now retired and sold business.) Has mild cam and a lot of comp products in engine. So sad to say not a whole lot of information about engine and trans other than I know it's a true 400 engine and turbo 400 transmission with his and her shifter.
Starts and idles fine. Revs great and hot starts fine also.
So problem is when I have engine idling I can shift it into reverse every now and then cleanly with no noise. But other times (50/50) it makes this horrid squeal/metallic noise. Sometimes it's for a quick second other times I need to get out of gear immediately. Hasn't done it in any other gear. I have taken inspection cover off and the teeth on flexplate do look like they have made contact with starter. And not in a good way. Is it possible there something with the wiring where the starter would pop in and out spuratically? Also wants to stall out when put into reverse or drive. It has tripower and I'm at the point we're only the primary carb is hooked up and all my vac lines are attached. Double checked and re checked trans fluid. Has power brakes also. And customer wants to drive it tomorrow.......... Any help would be appreciated! Thanks!


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## PontiacJim (Dec 29, 2012)

Kevin123! said:


> Hello all, I've been searching around for the fix to this problem for a bit. But haven't seem to find an answer that works for me yet. Quick overview of vehicle. Customer that I painted car for died and a friend of mine bought it. The original owner had motor build up pretty well. (Built 6 years ago and never came with proper build sheet as engine builder is now retired and sold business.) Has mild cam and a lot of comp products in engine. So sad to say not a whole lot of information about engine and trans other than I know it's a true 400 engine and turbo 400 transmission with his and her shifter.
> Starts and idles fine. Revs great and hot starts fine also.
> So problem is when I have engine idling I can shift it into reverse every now and then cleanly with no noise. But other times (50/50) it makes this horrid squeal/metallic noise. Sometimes it's for a quick second other times I need to get out of gear immediately. Hasn't done it in any other gear. I have taken inspection cover off and the teeth on flexplate do look like they have made contact with starter. And not in a good way. Is it possible there something with the wiring where the starter would pop in and out spuratically? Also wants to stall out when put into reverse or drive. It has tripower and I'm at the point we're only the primary carb is hooked up and all my vac lines are attached. Double checked and re checked trans fluid. Has power brakes also. And customer wants to drive it tomorrow.......... Any help would be appreciated! Thanks!



Year?????

Has to be a wiring issue if you know for a fact it is the starter engaging. You should only have the "Purple" wire going to the starter solenoid which activates the starter when you turn the key. You may have the wires touching down at the solenoid or somehow the battery cable from the battery is making contact on the solenoid. Could be a bad solenoid, could be a bad starter - but never had or heard of this issue. Check wiring first as it sounds like when you go from Drive to Reverse, the engine is probably shifting/torquing over and might be causing the electrical contact somewhere.

If stalling out, what is the idle RPM in gear? May be too low.

What is the engine vacuum reading at idle?

Make sure the check valve and rubber grommet on the brake diaphragm is good and working. This can be a vacuum issue.

Check the vacuum line/hose going down to the TH-400 modulator. Make sure no leaks.

Could be a timing issue. What is your Initial timing at the balancer with vacuum advance disconnected? What is the balancer timing when you connect the vacuum advance?


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## Kevin123! (Oct 27, 2020)

1967. I don't know for a fact it's wiring. It's the only thing I could think of seeing that the teeth look like they are hitting something metal. All wiring is new harnesses from m&h wiring. The engine has a noticeable torque/shift side to side when shift into gear. Idle rpm is 900-1,100. Engine vacuum is at 15. Initial it about +10 degrees and vac advance connected at 2500 rpm is about +34. I've thought about bringing idle up. But nervous of how hard it will shift into gear. Tonight I removed brake booster and plugged line and had same issue. If I didn't think it was starter issue. Any advice on what might be making the noise? I'm a bit baffled. The only thing I haven't done is drop the transmission pan. Also is it normal to be able to flex trans mount brace by hand. There is a lot of give in it. All new mounts.


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## Mine'sa66 (Oct 30, 2019)

None of the engine/trans moving around is going to effect the relationship between the flexplate and the starter.
That's a tricky one, Jim might be onto something in that perhaps a wire touches in reverse.
Perhaps the bendix in the starter is bad and going to reverse causes the gear to slide into the flexplate?


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## Kevin123! (Oct 27, 2020)

Quick update. I inspected the wires best I could without pulling starter. Which with how buried they are I guess that doesn't say much. But I found that although the nuts were tight there was slop in the u joint that connects end of driveshaft to rear end. After fixing that. I started it up and it seemed to fix the noise and idle issue. I backed it out of the driveway and 30 seconds later when I went into reverse same noise occured. And the stumble to stall happens also. I only have the primary carb on. And blocking off where the secondaries go. I double checked float and adjusted the float drop better. Same issue. Now that the exhaust is nice and got it's a perfect time to drop the starter and check that. One more thing. When I look at the starter nose. The shaft that the starting gear rides on. Should that be flush with the nose? The shaft on this starter seems to be recessed. A bit too much? The engine seems to have a lot of load on it when put into gear.


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## Kevin123! (Oct 27, 2020)

so the wires seem right and not touching anything. I noticed some hash marks in the starter housing. Used a Dremel to open it up a bit. But it looks like the flex plate has hit it before. But no shiny metal to indicate it happened recently. Also trans and engine were connected before I got the car. Is the bevel on the teeth suppose to face engine or away? I rotated flexplate but have not seen any normal "engine side" writing. I'm wondering if buying a new starter would be one way to cancel that scenario out. Thanks to anyone who has opinions that may help.


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## Mine'sa66 (Oct 30, 2019)

Kevin123! said:


> View attachment 145858
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> View attachment 145859
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> ...


Can you stick your finger/screwdriver in there and easily move the starter gear out? It should not.
The flexplate shouldn't have beveled teeth at all.
At the end of the day, if you find nothing else, I'd change out the starter. Cheap and easy.


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## Kevin123! (Oct 27, 2020)

Mine'sa66 said:


> Can you stick your finger/screwdriver in there and easily move the starter gear out? It should not.
> The flexplate shouldn't have beveled teeth at all.
> At the end of the day, if you find nothing else, I'd change out the starter. Cheap and easy.


I can have a new starter by tomorrow afternoon. Which I think is worth it to eliminate that scenario. I can move the starter gear out with a screw driver. With a little pressure. It's not sloppy. And retracts immediately. I'm going to drop the pan and see if there are any little metal gifts in the bottom of the pan for me. Just a thought here. Would a bad ignition switch spuratically engage starter?


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## Mine'sa66 (Oct 30, 2019)

Kevin123! said:


> I can have a new starter by tomorrow afternoon. Which I think is worth it to eliminate that scenario. I can move the starter gear out with a screw driver. With a little pressure. It's not sloppy. And retracts immediately. I'm going to drop the pan and see if there are any little metal gifts in the bottom of the pan for me. Just a thought here. Would a bad ignition switch spuratically engage starter?


It could. Pretty unusual, but possible. Same with the solenoid. 
Filings from the starter/flexplate are not going to make it into the oil pan.


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## Kevin123! (Oct 27, 2020)

I was thinking of dropping the pan to see if maybe this is an internal issue with transmission. I think I'll order starter and ignition switch and see how it goes from there. Thanks for the response!


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## Mine'sa66 (Oct 30, 2019)

Kevin123! said:


> I was thinking of dropping the pan to see if maybe this is an internal issue with transmission. I think I'll order starter and ignition switch and see how it goes from there. Thanks for the response!


I think I'd just begin with the starter and worry about the ignition switch later. That would be a real longshot. Possible, but really unlikely.
May the automotive gods smile upon your project!


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## RMTZ67 (Mar 12, 2011)

Are you able to get it on a lift and listen to it?


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## Kevin123! (Oct 27, 2020)

Sadly I'm not able to. And I'm a 1 man shop so it's hard to be at 2 places at once.


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## Kevin123! (Oct 27, 2020)

Well! For all those of you on the edge of your seat to see what the problem was. I've diagnosed it is the starter engaging when I put pressure on the reverse gear.


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## PontiacJim (Dec 29, 2012)

Kevin123! said:


> Well! For all those of you on the edge of your seat to see what the problem was. I've diagnosed it is the starter engaging when I put pressure on the reverse gear.


Still sounds like a wire issue. In reverse, reverse lights should be activated. Check for that.

Suggest you get a wiring diagram from M&H and do some tracing. Something is not connected correctly. See how many wires on the solenoid seeing it is not factory. There has to be power being transferred over to the wire on the solenoid that is causing it to kick in.

You may have to test wires with a test light one wire at a time.


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## Kevin123! (Oct 27, 2020)

2 purple wires on neutral safety switch seemed to be culprit. Switched then around and so far things seem normal.


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## 71 Lemans Convert (Jul 17, 2013)

I had a similar problem and found out that the battery needed replacement.


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## 2005firstgoat (Jul 2, 2021)

Sounds like your crankshaft thrust bearing is wiped out allowing the crank to move forward and aft in the block.
Raise the car on a lift and drop the f/w inspection cover and pry the converter forward then backward and measure the movement. My guess is the movement will be visual not requiring any measurement.


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## PontiacJim (Dec 29, 2012)

Kevin123! said:


> 2 purple wires on neutral safety switch seemed to be culprit. Switched then around and so far things seem normal.


That will do it, figured it had to be a wiring issue.


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## joet2442 (Nov 3, 2021)

Neutral safety switch


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## PontiacJim (Dec 29, 2012)

joet2442 said:


> Neutral safety switch



The problem was found and fixed by *Kevin123!*. Post #16 above:

"2 purple wires on neutral safety switch seemed to be culprit. Switched then around and so far things seem normal."


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## joet2442 (Nov 3, 2021)

Glad you got it fixed


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## Noangelbuddy (Dec 6, 2017)

PontiacJim said:


> The problem was found and fixed by *Kevin123!*. Post #16 above:
> 
> "2 purple wires on neutral safety switch seemed to be culprit. Switched then around and so far things seem normal."


When I read the posts, my money was on the starter. There was no mention of shimming.

I have to admit I was surprised to read switching the neutral safety switch wires solved the problem. Unless the problem is intermittent in nature and comes back? Hope not. Intermittent problems are a royal pain.

Live and learn.


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## BLK69JUDGE (Jun 10, 2010)

I thought the nuetral safety switch took power from one of the purple wires that is hot when the ignition is turned to start position ..full right ...
and powers the other tab and purple wire on the switch in park or nuetral to activate the starter solenoid ,.,,, and start the car

the switch works as a power interupter .... 

I dont think swapping the purple wires in the plug should have any effect on the issue being discussed.... as in starter being activated in reverse,,,


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## PontiacJim (Dec 29, 2012)

Well, I was surprised at the fix myself as I can't think how a starter would go backwards in the first place? Maybe the PO was looking at the distributor rotor which goes CCW and was used to a Chebby that goes CW?

May have been pulling our legs just to see our reactions/answers?


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## 03Marauderman (Dec 29, 2018)

Not my GTO but my 03 Marauder....I kept hearing what I thought was a tin noise like those metal tabs that are welded on cat converters....Nope, however while driving the noise would come & go....turned out to be the bendix gear floating back & forth hitting the ring gear....Rebuilt the started...problem solved.........


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