I replaced the radiator and transmission cooler lines a couple weeks ago and I'm having problems with the transmission not wanting to go into gear when it is cold but when the transmission is warmed up it will go into gear like it should. Any ideas on what could be happening?

 

Welcome to the 2nd Gen Neon forum.
I see you don't have any replies yet so I'll see if I can get things started.
Is the tranny fluid level correct when cold?
Make sure all electrical connections are securely fastened.
Have you scanned the tranny computer for trouble code clues? If so, post All code Numbers, as they can help focus a trouble shoot.

 

The fluid level when it is cold should be between the two holes on the dipstick correct? If so then I put too much tranny fluid in there because it is over the second hole. I will recheck the connections. I have not scanned the computer for codes, can that be done at a local auto parts store?

 

The engine must be at operating temperature with the transmission in neutral to properly check the transmission fluid level.

http://www.dummies.com/home-garden/c...mission-fluid/

Auto parts store will check for stored codes for you. Or you can buy a scanner at walmart for like $20.

 

The reason I suggested checking the fluid level cold is the Owner Manual describes how to interpret the dipstick Warm & Hot level indicators. If the transaxle is over filled & the fluid is cold, it can become aerated from contacting rotating parts its not supposed to touch. Being cold, the fluid would be able to hold onto the bubbles longer/they won't pop as quickly as hot fluid will.
SO, cold aerated fluid can cause low line pressure problems, as the tranny pump cant pressurize aerated fluid. Think of the aerated fluid as being springy. Fully warmed fluid air bubbles can pop easier, so maybe not cause it to be unable to shift into gear. Anyway, refer to your year/model Owner Manual for the proper fluid level depending on temperature, adjust as necessary.

If its over filled, you can remove the tranny dipstick & slip a piece of tubing thats Longer than the dipstick, down the tranny fill tube (longer so if comes disconnected it wont drop into the tranny pan, causing you to have to drop the pan to retrieve it) & connect the tubing to a marine lower unit hand pump syphon tube, to pump excess fluid out, to get the correct level.
Even a trigger spray bottle pump, or syringe can be used if you don't have a lower unit gear oil pump, it just takes longer to pump a larger volume out.

Anyway get the cold fluid level right, see if that fixes it not wanting to go into gear cold. If it does, Fully warm the fluid as described in the Owner Manual & recheck the level Hot as jkeaton has suggested..

If still no joy, try scanning the computer for trouble code clues & post All code Numbers. We can enable the vehicle computer to put up trouble code clues on te dash display, by turning the ignition key from Off to On three times (Don't crank the engine), stopping at On the Third time. But I don't know if it'll output stored tranny controller codes, or if it just outputs engine trouble codes???? Maybe a member that knows will chime in & enlighten us if it'll output Any/All pending, or set system trouble codes.
Most auto parts store code readers will only read engine trouble codes, so may not be of much help.

The inexpensive ELM. scan tool, running a good diagnostic software on our choice of viewing device, can access All of the vehicle computer controllers.
I use the ELM running FORScan that's tweaked for Fords & it'll access the engine, tranny, ABS, anti-theft, & body computer controllers on my Fords, so it's been really helpful trouble shooting other than engine problems & has paid for itself on its first use trouble shooting a ABS problem. It also found some body codes I didn't know I had for a power window problem I'd just developed, that helped me fix the power windows at no cost. SO, if you like trouble shooting & turning your own wrenches, consider one, they're inexpensive, so can be a good investment & addition to our electronic tool box.
More thoughts for consideration, let us know how it goes.

 

Sorry, I thought he was asking if you check it when it’s cold. Lol

 

No problem, it is best we check it Hot, as outlined in our great unread document called "Owner Manual". Since it seems the problem came about just after the repairs & he topped off the tranny & its reading Above the second notch on the dipstick cold.
The unknowns are was it checked with the engine Off??? Or was it checked with the engine at idle for several minutes, on level ground & after having just been shifted into All gears, to make sure the torque converter, valve body, radiator cooler & lines were full, so he was getting an accurate cold/warm fill indication. If it was still indicating above the second notch cold, it sounds like he over filled it after the repairs top off.

SO, marksneon, let us know how you've been checking the tranny fluid level & if it was indeed over filled & how its doing after adjusting the fill level.