Trans Won't Engage After Sitting Overnight

[money pit]

I have a 727 that was rebuilt in March 2019. I had the trans rebuilt but I installed it. It's a floor mount shifter. When the car sits overnight or on a slight incline, overnight, I have to run it through Neutral, Drive, Neutral, reverse a couple of times until the trans engages. I did change the dip stick because the old one was broken (the handle). I changed the dip stick only, not the outer tube. I compared the new to the old, they looked the same length and the markings were the same.. When the engine is hot, it shows full. I'm checking it in neutral (per the Trans builder). The trans seems to shift properly. Could the dip stick be off? It has 8 quarts of ATF (the converter was empty). Do I need to add a little more ATF? Thanks

 

[oldkimmer]

The builder should have changed the manual valve so it circulates in park. Also the converter hub may be on the small side which makes the problem worse. What u have is called morning sickness. The converter drains back into the pan then needs to refill on the next cold start. Putting it in neutral for a couple of minutes works wonders. Kim

 

[toolmanmike]

Yep, converter drainback. There is a fix for that. Make sure you check the fluid level correctly. Warm, level, and in neutral. Block the wheels for safety.

 

[moparleo]

Common on very Mopar I have ever owned over the last 40 years More so on the ones that don't get driven everyday. Since they need to warm up before the choke opens ( most people are spoiled with fuel injection and electronic transmissions and may not have much/any experience with pre 80's cars) I just put it in neutral during warmup. Problem solved. Not a problem really unless you have external leaking. It is also best to run it about 1 pint low. It is better to run it slightly low on fluid as opposed to higher than normal levels. Which can cause problems.


(by Bill Watson)

Automatic transmission fluid is added, through a funnel, to the dipstick tube on the passenger side of the vehicle. Many car parts stores sell a funnel with an attached hose, which fits perfectly into the tube. [For emergencies you may want to carry a disposable funnel.]

The transmission should be at its normal temperature before checking, and the car should be on truly level ground. Apply the parking brake firmly with the engine at idle, then shift into each gear, momentarily ending in Neutral — not Park.

The fluid level should be at the full mark on the transmission dipstick, or slightly below it — definitely not above Full. If it is below the “add one pint” mark, add fluid and check the level again as per above to ensure the level is between "ADD" and "FULL".

 

[money pit]

The builder should have changed the manual valve so it circulates in park. Also the converter hub may be on the small side which makes the problem worse. What u have is called morning sickness. The converter drains back into the pan then needs to refill on the next cold start. Putting it in neutral for a couple of minutes works wonders. Kim

Thanks for the info. The trans has a one year warranty from the time I installed it. I installed it in Oct. since I had hand surgery.

 

[money pit]

Common on very Mopar I have ever owned over the last 40 years More so on the ones that don't get driven everyday. Since they need to warm up before the choke opens ( most people are spoiled with fuel injection and electronic transmissions and may not have much/any experience with pre 80's cars) I just put it in neutral during warmup. Problem solved. Not a problem really unless you have external leaking. It is also best to run it about 1 pint low.

I do have a leak. I just changed the O ring on the speedo gear housing. I also changed the cable (second time). The cable seems to leak at the crimp. Why do you recommend running the trans a pint low? Thanks

 

[money pit]

Yep, converter drainback. There is a fix for that. Make sure you check the fluid level correctly. Warm, level, and in neutral. Block the wheels for safety.

Thanks. The color of the new dipstick is dark grey so it's a little hard to read. It's a little over filled. May be a quarter of a pint.

 

[toolmanmike]

Thanks. The color of the new dipstick is dark grey so it's a little hard to read. It's a little over filled. May be a quarter of a pint.

That's not enough to worry about.

 

[Mastertech]

The 727 has an anti-drain back valve in the valve body to prevent the converter from draining down overnight. Sometimes after an overhaul they can stick. I had the same problem. Big pain in the you know what.

 

[money pit]

The 727 has an anti-drain back valve in the valve body to prevent the converter from draining down overnight. Sometimes after an overhaul they can stick. I had the same problem. Big pain in the you know what.

Thanks. I'll get it checked out.

 

[Big G]

I do have a leak. I just changed the O ring on the speedo gear housing. I also changed the cable (second time). The cable seems to leak at the crimp. Why do you recommend running the trans a pint low? Thanks

If the cable is leaking the cup seal on the shaft is bad, on mine the shaft was worn, 98000 miles, so changed the whole speedo unit. Make sure it is indexed to the correct number.