420a Swap - Auto tranny won't sync, Help!

[RomeoV]

Hi guys,

I'm racking my brain over this problem and my car has been in the shop for 2 weeks now stuck with this issue, I'm so hoping someone can help.

Long story short, I recently swapped my 420a out with a much more powerful total rebuild stage II racing block from Slowboy (who I seem to get vast opinions on from good to bad in forums... latest consensus seems used to be bad but now good) Anyways, I got it secondhand, brand new cheap, and my mechanic got it swapped in with no real issues (minus a sensor harness that needed to be upgraded/switched).

Here's the problem. Although it bolts up to my auto trans.. it will not start, nor spin freely by hand. We are now convinced some part needs to be swapped out, but we don't know what or why.

My eclipse is a 96 GS, and we don't know exactly what donor car the new 420a block came from, but there has got to be a change in parts somewhere along the line. I know there are lots of syncro changes in 2g years, but I am not enough of a gear head to even know if that applies in this case. My mechanic seems to think it might be a neon 420a hence the problem, but I have been told all 420a blocks are essentially identical.

Does anyone know what the problem could be? Or what changes were put in place between 96-99 that would not make the tranny work with a newer 420a right out of the box? Flywheel? torque converter? I don't mind getting the parts, we just have no idea which to get. Thanks

P.S. my tranny worked perfectly fine up to the second we pulled the engine, so I know at least it's functional.

 

[2qik4u]

did you make sure the motor itself spun freely when you got it????

 

[bullettdsm]

Here's the problem. Although it bolts up to my auto trans.. it will not start, nor spin freely by hand. We are now convinced some part needs to be swapped out, but we don't know what or why.

I got a kick out of this one. How did you determine that some random part (that you don't know what it is) needs to be switched out, ?

Anyway, did you remove the torque converter? Or did it fall away from the tranny? There should be 3 clicks that tell you the torque converter is on. If you do not have it all the way on, it may lock up your motor.

You are trying all this in neutral, right, ?

And the previous posters question is quite valid, you did check to see if she spun before you put her in right?

There should be no difference in blocks bolting up between Neon or Mitsubishi.

All things being equal and correct, I would bet on the torque converter not being all the way on.

MB

 

[2qik4u]

i totally agree!! they pretty much all swap out no problem!! the torque converter is what i was kind of leaning towards but want to know if the motor spins at all?? didnt want you to try anything with the torque converter if the motor itself doesnt spin. i know slowboy racing and know that when a friend of mine bought a full motor from them they said it had a forged crank in it but it was a bullshit cast crank and he had to get a lawyer involved to have the situation righted!! they are pretty shady people and i wouldnt be suprised if you got a motor from them that didnt spin to start with!!! so check that the motor spins and then check that the torque converter is installed correctly!! after that if you still have problems post more and we will try to help you best we can.

 

[RomeoV]

Hi guys, thanks for your help this far.

Well, I was finally able to get over to the shop today and talk to my mechanic.

1. Yes, the motor spins completely freely on it's own
2. yes, the torque converter is all the way on, they even totally dropped the whole tranny and tried it all again, it clicked three times and bolted up perfectly.

I wish I knew more about this stuff as I sound like a total n00b saying this, but best I can describe what he said was that everything spins freely on both ends literally until it's fully clamped together. As in, he can spin everything fine, until it clicks on and at that point , nothing moves.

yes, this is all in neutral.

He seems to think it's now a problem with the transmission itself, or perhaps something with the electronics. Which we both agree seems pretty far fetched as it has never had a problem ever and drive to the garage on it's own, shifting just fine.

Did the flywheels change at all during the 95-99 years? Did anything change between years that might be causing this problem? I'm sure the block isn't exactly a 96 as my tranny is.

We're taking it to a trans specialist this weekend so we'll see. Thanks for your continued help, I know it's funny when I have no clue what I'm talking about half the time heh.

 

[bullettdsm]

Hmm flexplate on backwards ?

MB

 

[2qik4u]

im voting wrong flexplate or wrong torque converter but it is just a guess. dont buy anything till you know for sure what you need.

 

[96_killer]

Hmm flexplate on backwards ?

MB

I half to say that this is most likly, beacuse i was a dum nut once and maybe still am. But I did this and nothing moved...
it bind up the torque converter to the tranny!!!!

 

[2qik4u]

did you get the problem fixed yet??? let us know if you made any progress!!!!!

 

[RomeoV]

Hi guys,

Well, it's been like over a month and the problem has finally been solved. I don't know all of the technical details, but the end result was spot on with 2qik4u, and 96_killer's responses. We took the trans to a specialist and the torque converter was indeed completely binded up to the tranny. Now I don't know exactly what caused it, but we know that it was not installed correctly and when the motor was first started up, that's when it binded. I believe the converter wasn't completely clicked in.. but maybe the flex plate was on backwards who knows? Thankfully, it was repairable, my mechanic covered the cost, and I had some "batwings" put on in the meantime to keep my pin from slipping out and slicing a hole in the case which happens a lot on these Chrysler transmission I hear.

The trans has now been successfully installed and lined up in the car and we go for first start on the new motor this week, thanks again for all the help and suggestions!