Cold 727 slipping. Any ideas?

[Joseph James]

I left for work and had to back up my driveway which is inclined. Transmission slipped some. Got to a steep hill at a stop sign. Called rolled back when I tried to pull out. Hit gas hard and it chirped tires and went on.

Fluid level is good. I have been letting it sit in neutral a few minutes before I leave and that seems to help.

No problems once it’s ran a few miles.

rebuild time?

 

[mopar440]

I was gonna say converter drain back. What happens if you put it in nuetral, rev it to 1200 for 5-10 seconds, does it act up?

 

[Joseph James]

I was gonna say converter drain back. What happens if you put it in nuetral, rev it to 1200 for 5-10 seconds, does it act up?

I haven’t tried that yet. I’ll try it in the morning.

 

[jcslocum]

Probably pump seals. I'm not an expert.

 

[rkrochen]

Sounds like you are losing pressure at slower engine rpm’s. Could be due to several reasons but likely due to the fact that its time to rebuild it. Things that could contribute are pump could be worn, seals getting hard or deteriorating, clutch pacs wearing out and could even be a bad converter.
Recheck the oil when hot and in neutral. Is it full, doesn’t take much below the add line to cause problems. What is the colour like is it dark or burnt smelling. If so it’s likely on its last legs.

 

[JC68vert300]

I had the same problem, until I read here the trans pump does not run in the park position. Once I start it, I place it in neutral while it warms up, it is smooth as silk in reverse every time.

 

[413]

Backing up an incline with a cold 727 is a really bad thing to do. Can you back it down there and drive out on D?



and yes run it in neutral before moving.

 

[Davea Lux]

How long has it been since the transmission was serviced? A partially clogged filter drops the oil pressure to the transmission especially when it is cold and that can cause the symptoms you are describing. Drop the transmission pan and inspect/replace the filter. If the pan is full of debris, you are headed for a rebuild.

Dave

 

[Joseph James]

How long has it been since the transmission was serviced? A partially clogged filter drops the oil pressure to the transmission especially when it is cold and that can cause the symptoms you are describing. Drop the transmission pan and inspect/replace the filter. If the pan is full of debris, you are headed for a rebuild.

Dave

I will check it but it was serviced by a transmission guy in October of 2018 right after I got it. I actually had no 3rd gear and got it to his shop in 2 on the interstate driving about 50 mph. He called and said it had no filter. He replaced and filled. I have refilled it when the cooler lines were leaking and when it had to have a shift selector seal. I should add it leaked fluid from dust cover after sitting 3 weeks last winter when I was replacing suspension parts. I topped it off then, too.

I am putting some money back for a rebuild. Guy says $900 which is what he charged for rebuilding the transmission in the 89 Dodge I had. He says he can drop a newer rooster comb in so I can use a 3 pin NSS allowing me to have reverse lights.

 

[Davea Lux]

I will check it but it was serviced by a transmission guy in October of 2018 right after I got it. I actually had no 3rd gear and got it to his shop in 2 on the interstate driving about 50 mph. He called and said it had no filter. He replaced and filled. I have refilled it when the cooler lines were leaking and when it had to have a shift selector seal. I should add it leaked fluid from dust cover after sitting 3 weeks last winter when I was replacing suspension parts. I topped it off then, too.

I am putting some money back for a rebuild. Guy says $900 which is what he charged for rebuilding the transmission in the 89 Dodge I had. He says he can drop a newer rooster comb in so I can use a 3 pin NSS allowing me to have reverse lights.

While you have the pan off, also check the band adjustment, a lot of transmission shops have forgotten this lost art as most modern transmissions have no adjustment.

Dave

 

[CBODY67]

In the mean time, you might try some "transmission conditioner" to soften the (suspected) hardened-with-age seals a bit. GM had a product, "Automatic Transmission Conditioner", but there are probably other similar products out there. A "seal softener and expander", plus some detergent additives. The Valvoline MaxLife atf already has these things in it, I believe.

If the problem is "only when cold", but not "when at operating temp", it could be a fluid level issue and/or a seal ring (somewhere) that is not working fully when cold. A shot of additive might help in the short term or until you can get it rebuilt. That "front of the trans leak" you described could be a front pump outer edge rubber (band) seal or the front pump lip seal (where the converter slides into the pump).

Seems like there is a "dot" below the "Add" line, which is the "Add" line for 0 degrees F? I know there's one on GM THM350 and THM400 dipsticks, but not sure about one on TF dipsticks.

When you do check the fluid, cold and hot, with your foot on the brake, run the shift level through the full quadrant, pausing in each gear selection position, ending in "N". Apply the parking brake, too!

Just some thoughts,
CBODY67

 

[Joseph James]

While you have the pan off, also check the band adjustment, a lot of transmission shops have forgotten this lost art as most modern transmissions have no adjustment.

Dave

Could band be why I have never had kickdown? The linkage I did per FSM. I usually shift it to 2 myself when getting on interstate or helping my manual brakes out.

 

[Joseph James]

In the mean time, you might try some "transmission conditioner" to soften the (suspected) hardened-with-age seals a bit. GM had a product, "Automatic Transmission Conditioner", but there are probably other similar products out there. A "seal softener and expander", plus some detergent additives. The Valvoline MaxLife atf already has these things in it, I believe.

If the problem is "only when cold", but not "when at operating temp", it could be a fluid level issue and/or a seal ring (somewhere) that is not working fully when cold. A shot of additive might help in the short term or until you can get it rebuilt. That "front of the trans leak" you described could be a front pump outer edge rubber (band) seal or the front pump lip seal (where the converter slides into the pump).

Seems like there is a "dot" below the "Add" line, which is the "Add" line for 0 degrees F? I know there's one on GM THM350 and THM400 dipsticks, but not sure about one on TF dipsticks.

When you do check the fluid, cold and hot, with your foot on the brake, run the shift level through the full quadrant, pausing in each gear selection position, ending in "N". Apply the parking brake, too!

Just some thoughts,
CBODY67

I will look for that product and see if it helps. Thanks for that info.

Front pump seal better not be leaking. I replaced it when I swapped the engine and I didn’t buy a cheap one.

I’ll try shifting through. No parking brake, though. Someone cut it off long ago and it is on my list of things to repair.

 

[Davea Lux]

Could band be why I have never had kickdown? The linkage I did per FSM. I usually shift it to 2 myself when getting on interstate or helping my manual brakes out.

Those older transmissions (pre-71) did not have a true kick down like the later ones did. The transmission should still shift down when the governor and hydraulic pressures are correct for it to do so. The band adjustment if it is way out might make the downshift erratic, more likely you have low oil pressure from an internal leak, worn pump or clogged filter. If you decide to rebuild the transmission, invest in the later valve body for improved down shift and better overall performance along with the late style rooster comb for the 3 pin switch.

Dave

 

[Big_John]

Just a quick question... You did check the level with the car idling in neutral... Correct?

Just making sure... It's tripped up a few with the same symptoms.

 

[Joseph James]

Just a quick question... You did check the level with the car idling in neutral... Correct?

Just making sure... It's tripped up a few with the same symptoms.

Yes, I did. I have a level driveway right in front of the house. I usually put a stone behind the back wheel since I have no parking brake.

 

[rags]

Front pump seal

pump seal is the big rubber band that goes around the perimeter of the pump. seals the pump to the case. will leak while sitting.

 

[CBODY67]

The '71+ valve body will get you "Part-Throttle Downshifts", in addition to the WOT-only downshifts like you already have. Rather than "lugging" things along in high gear, right up to the WOT area in the throttle/kickdown linkage, it'll downshift automatically and then upshift at an appropriate speed for the throttle input. Very similar to what the GM transmissions do with their vacuum modulator set-up (i.e., THM350 and THM400).

Rather than "a rock", you might head to Harbor Freight (or similar) to purchase a "wheel chock" which will more positively index with the tire and ground, consistently. Might also find something in the RV section of other stores.

Keep us posted, please,
CBODY67

 

[mopar440]

Rebuild yourself if possible, that price seems a little high. I watched vids and bought the book. Bought the rings/clutches/seals for like $80. Checked all tolerances, and they were good. It really is easy. Once you get it apart, you'll be surprised

 

[Big_John]

I will check it but it was serviced by a transmission guy in October of 2018 right after I got it. I actually had no 3rd gear and got it to his shop in 2 on the interstate driving about 50 mph. He called and said it had no filter. He replaced and filled. I have refilled it when the cooler lines were leaking and when it had to have a shift selector seal. I should add it leaked fluid from dust cover after sitting 3 weeks last winter when I was replacing suspension parts. I topped it off then, too.

I am putting some money back for a rebuild. Guy says $900 which is what he charged for rebuilding the transmission in the 89 Dodge I had. He says he can drop a newer rooster comb in so I can use a 3 pin NSS allowing me to have reverse lights.

OK, there's your answer...

Transmissions can be nursed back to health temporarily. They'll act OK, usually long enough for the "For Sale" sign to do its job but you can always expect some sort of issue somewhere down the road.

A 727 is one of the easier transmissions to rebuild and I'll suggest doing the part throttle downshift upgrade too. You don't need the entire valve body though. Get in touch with this guy for the pieces. T'Flite Patty's Shop Mart | eBay Stores Better sooner than later though, he keeps threatening to retire.

$900 is reasonable if they are removing and reinstalling the trans.