Auto trans stumper

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jos51700

jos51700

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Not an A-body, but close enough:
my '93 Dakota (5.2, automatic that's been replaced a billion times, I think it's an A-518 ) started making a brief grinding noise when putting it into gear, either from D to R or vice versa, and occasionally hitting the N in between. It sounds a LOT like bumping the starter with the engine running. From underneath, you can even hear something winding down after the grinding like a pinion gear does.

Initially I thought the shifter mechanism was shorting wiring in the column because it has a slight mechanical resistance when it initiates the grinding. I can't get it to hold the grinding, only bump it.
I checked all the wiring, and it was all good. Had the wife sit in it and shift and followed it under the hood and down to the trans, and eventually disconnected the linkage at the trans. Worked the lever to put it in gear and it still does it. Reconnected the linkage and it only happened once. I tried to put my hand on the starter and then the trans to isolate the noise but it only happened with my hand on the trans pan and it sure felt like it was in the trans, but that could be the same with the starter bumping too.

I'm wondering if a crapped neutral safety switch could cause the starter to bump somehow but I don't think so. But, my knowledge of all things automatics is a little limited (yeah, like hurricanes are "windy"). I'm also wondering if a servo is sluggish causing it to try to hit two gears or reverse and first at the same time or something, but since I don't think the mopar transmissions have any mechanical gears engaging or any of that, I doubt it.

Thoughts? Ideas? Free parts?
Thank you FABO
John
 
I think your on the right track, sometimes that rear servo can get cocked in the bore.

You COULD do a line pressure test with an engine oil gauge at the various taps, see if everything is well..



But, I'd drop the pan and adjust the rear band, while your at it the front one too. Look for crap in the pan.

2 1/2 for the front
4 turns for double wrap rear
2 1/2 if by the off chance it's single wrap rear

Inspecting the servos as you go. The best way to go about that is drop the valve body and fire up the compressor, and start blipping 25PSI at the small adjacent holes for the front and rear servos but that's if you don't see an issue.

autotrans-pressure-testports.jpg
 
Holy crap! You have a lot of faith in me! And assuming I have compressed air :-(

Is there a symptom that would occur in daily driving that would indicate similar issue? I'm assuming that by saying that it cocks in the bore that you mean it is doing this occasionally?

What would happen if I just drove it like this? I was also thinking about trying to start it in neutral and put in D or R from there and see...
 
I spouse you can, but I wouldn't.

There is a troubleshooting matrix in the 42RH ATSG manual, but first things first.

Take it back and throw it at whoever rebuilt it, that's the easiest way.
 
Lol the trans that is in it is a '94, from a Dak. Never rebuilt.
 
I have heard the over-running clutch do things like that. Unfortunately its the first thing that goes into the case..... Mine ran for an awfully long time like that(but I knew what it was).
 
Is this the same overrunning clutch that makes things go boom? That thought did cross my mind when I was under the truck and the wife was shifting it.
 
jos51700 said:
Is this the same overrunning clutch that makes things go boom? That thought did cross my mind when I was under the truck and the wife was shifting it.
Click to expand...

Yes it is, but it requires some pretty fair RPM's to explode.
The sound you are hearing may be the pressure regulator valve "buzzing" and that can be caused by a plugging up filter. (one of the reasons)

You may want to pull the pan as suggested and post a pic of the pan contents.
Then we can assist in the rear band and servo inspection while you are in there.
 
jos51700 said:
Not an A-body, but close enough:
my '93 Dakota (5.2, automatic that's been replaced a billion times, I think it's an A-518 ) started making a brief grinding noise when putting it into gear, either from D to R or vice versa, and occasionally hitting the N in between. It sounds a LOT like bumping the starter with the engine running. From underneath, you can even hear something winding down after the grinding like a pinion gear does.
John
Click to expand...

Sometimes the starter solenoid can stick when that big copper plated washer welds across the contacts. It has an over-running clutch in it too. But Ima thinking thats not your problem, this time.
 
OK, an update on this.

Last time, I got underneath and was having the wife shift it while I listened/felt for the source...and the source stopped.

Until yesterday.

Yesterday, while towing, it had a phase of doing this 15-16 times and since I backing with trailer, it did it (lightly) every time from D to R and back. But, this was at night, and I noticed something; when it happens, the headlights dim briefly.

Manually operating the starter while in neutral matches the sound an light effects perfectly.

I'm 99.9% convinced it is the starter...so why? Last time I pulled the column apart and found no chafed wires and all I can think is the shift linkage chafing a wire, unless maybe the issue is in the neutral safety switch or solenoid/relay circuit somewhere?
 
All the neutral safety switch does is provide a ground to the starter solenoid so there's absolutely no way it could cause the starter to engage. Do this as a test. Next time you start it up pop the hood and the top off the relay block that's right behind the battery and remove the starter relay. Then go put it in gear and see what happens. By removing the starter relay you effectively unhook the starting circuit. If it still makes the noise it's nothing to do with the starting circuit and must be a mechanical problem
 
See if this download works........it seems to be the 42RH ATSG manual!!!!!!!!!!!!!!!

shop.ukrtrans.biz/wp-content/uploads/catalogs/42RH.pdf#page=1&zoom=auto,-91,482

42RE

shop.ukrtrans.biz/wp-content/uploads/catalogs/42RE.pdf

A727 / A904

shop.ukrtrans.biz/wp-content/uploads/catalogs/A727.pdf

D................'uh...........just fiddle around here.........

http://shop.ukrtrans.biz/?page_id=59349
 
fishy68 said:
All the neutral safety switch does is provide a ground to the starter solenoid so there's absolutely no way it could cause the starter to engage. Do this as a test. Next time you start it up pop the hood and the top off the relay block that's right behind the battery and remove the starter relay. Then go put it in gear and see what happens. By removing the starter relay you effectively unhook the starting circuit. If it still makes the noise it's nothing to do with the starting circuit and must be a mechanical problem
Click to expand...

Right. I'm wondering if the relay has a short internally that's completed by the nss...
 
Had a 1982 Ram Charger do this. Replaced the neutral safety switch and it still did it. I unplugged it and it quit. Something in the wiring. I didn't have the truck long. Never figured it out. Try unplugging it, see if it quits.
 
fishy68 said:
If the start relay was shorted the starter would never disengage when you let off the key.
Click to expand...

If the relay doesn't get a ground, it can't start, right? And it grounds through the NSS.

But I see what you're saying. It should try to start any time in P or N.
 
67Dart273 said:
See if this download works........it seems to be the 42RH ATSG manual!!!!!!!!!!!!!!!

shop.ukrtrans.biz/wp-content/uploads/catalogs/42RH.pdf#page=1&zoom=auto,-91,482

42RE

shop.ukrtrans.biz/wp-content/uploads/catalogs/42RE.pdf

A727 / A904

shop.ukrtrans.biz/wp-content/uploads/catalogs/A727.pdf

D................'uh...........just fiddle around here.........

http://shop.ukrtrans.biz/?page_id=59349
Click to expand...

Seeing A904 manuals on a russian website is awesome. Where do you guys find this stuff?
 
Update: since the neutral safety switch is all of ten dollars, and an easy swap, I figured I would stab one in.

Went to plug the plug back on, key off, and the starter bangs! Only briefly, but it hit two or three times when I lined up the plug and started to push it on. I've left it un plugged for the time being.
Also: no reverse lights.

So, shorted wiring in the nss circuit?
 
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