1972 Fury 727 Trans Pan Recs/Comments

[1970FuryConv]

My 1972 Fury has a pesky trans pan leak at the left front corner of the pan of the 727 small block transmission. The previous owner tried a cork gasket without success. I tried a rubber gasket as part of a Napa filter kit, also without success. At least in my case, the bolts were torqued to factory spec. I cleaned the pan thoroughly. I didn't see any warpage in the transmission pan as it lay flat on a table. However, I admit that the transmission oil pan is probably 46 years old, and I can't be sure what it does when it heats up.

Installed

So I was thinking of buying a fancy new deep well transmission oil pan for added stiffness at the mounting surface and hopefully better leak prevention. I found the following options on eBay. If you have any opinions about whether it's worth the money or what's causing the original pan to leak, I'd be glad to have them. They all come with new mounting bolts, gasket, and spacer to move filter deeper into pan. They all cost in the $150-$170 range.

 

[Davea Lux]

An OEM Chrysler one is a lot less expensive. You could also try putting a small bead of the red or black Permatex form a gasket on either side of the pan gasket, let it sit over night to set up. A small bead, you do not want any of it getting into the transmission pan. The only real advantage to the deep sump pans pictured is increased oil capacity with a drain plug on some models.

Dave

 

[CBODY67]

Is the "leak" a drippin' leak or an oily "seep"? Any oil, especially the thinner viscosity oils, will wick through a rubberized cork gasket, over time, no matter how much torque is on the hold-down fasteners. Rather than a "small bead" of the sealer Dave mentions, I personally like smearing a thin coat of high-heat black silicone sealer on ALL sides of the gasket. After it cures, then assemble. Cover the edges, too! This seals the gasket from the wicking action and might also give you the additional cushion to make up for any apparent non-flatness of the corner of the pan.

The deep pans do have their place, but are waaayyy overkill on a stock vehicle. That they are cast rather than stamped might be a plus, though. You can add a drain plug to the steel pan, if desired. B&M used to have those kits.

Whether you use Dave's orientation or my "trick", doesn't matter as long as the escape of atf is stopped.

CBODY67

 

[Davea Lux]

If the oil is seeping thru the gasket material, it will usually leak more when the car is warmed up and usually will not be leaking large quantities of oil. You certainly won't hurt anything by doing all 4 sides of the gasket as Willis suggested. If the car is leaving a puddle when parked, most likely there is a problem with the pan or some defect in the transmission case close to the sealing surface. You might want to check the case on the corner where it is leaking to be sure some stray gasket material has not found its way into one or more of the bolt holes preventing them from full seating .

Dave

 

[CBODY67]

Wondering if it really might be a shift shaft seal or the neutral safety switch that might be seeping enough to drip off of that particular pan corner?

CBODY67

 

[mrfury68]

Wondering if it really might be a shift shaft seal or the neutral safety switch that might be seeping enough to drip off of that particular pan corner?

That is a good possibility. I remember changing quite a few of those seals back in the day. I know of a few guys who went to the rubber encased steel gasket with very good results.

 

[Ross Wooldridge]

Over the years the bolt holes take an inward set from the bolt head's pressure, and then the pan rail deflects and leaks.

Here's an old grey-beard trick-

Take a ball peen hammer and tap the bolt holes on the INSIDE so that they sit proud of the outside surface a little.

This distributes the bolt head pressure along the pan rail surface a bit more.

 

[68 4spd Fury]

Is the "leak" a drippin' leak or an oily "seep"? Any oil, especially the thinner viscosity oils, will wick through a rubberized cork gasket, over time, no matter how much torque is on the hold-down fasteners. Rather than a "small bead" of the sealer Dave mentions, I personally like smearing a thin coat of high-heat black silicone sealer on ALL sides of the gasket. After it cures, then assemble. Cover the edges, too! This seals the gasket from the wicking action and might also give you the additional cushion to make up for any apparent non-flatness of the corner of the pan.

The deep pans do have their place, but are waaayyy overkill on a stock vehicle. That they are cast rather than stamped might be a plus, though. You can add a drain plug to the steel pan, if desired. B&M used to have those kits.

Whether you use Dave's orientation or my "trick", doesn't matter as long as the escape of atf is stopped.

CBODY67

To that I'd add put a dab of RTV on the bolts, the threads in case may be a little oversize or the tap broke through.

 

[Lefty71]

Deep pans are good for a little more cooling. Deep ribbed aluminum pans are supposed to add some stiffness as well. Im sure its overkill for stock, but whats a couple bucks for your baby?? Ive used the b&m one for years on one of mine that goes on the street and track, and its been together forever with no seepage. Like others have said, you are gonna have to investigate other areas to be positive. You can buy minor seal kits to catch all these problem areas as well. HTH, Lefty71

 

[65sporty]

This subject has been covered here, a lot of the guy's recommend this one.
Mopar Performance 02464324AC: A-727/A-518/46RE Oil Pan Gasket Molded Rubber - Re-Usable | JEGS
With some searching you can find it cheaper than Jeg's

 

[1970FuryConv]

If the oil is seeping thru the gasket material, it will usually leak more when the car is warmed up and usually will not be leaking large quantities of oil. You certainly won't hurt anything by doing all 4 sides of the gasket as Willis suggested. If the car is leaving a puddle when parked, most likely there is a problem with the pan or some defect in the transmission case close to the sealing surface. You might want to check the case on the corner where it is leaking to be sure some stray gasket material has not found its way into one or more of the bolt holes preventing them from full seating .
Dave

Thanks for all the answers. The pan does not leak while the car is running/warm. It has to sit parked for a while, then the drip starts, and a puddle forms below the left front corner. I cleaned the mounting surface completely. I don't think there's a chance of old gasket material being the problem. I should have checked the pan and mounting surface with a straight edge and also checked for and repaired dimpled bolt holes. I'll do that when I put the car back up in the air

On the shifter seal above the pan, I took the trans down and cleaned it thoroughly, when I had to replace leaking core plugs at the rear of the engine. While down, I replaced a bent fitting at the front trans cooling line. No leak at torque converter seal. I can look again, but the shifter seal above doesn't look like it's leaking since reinstall. With that side of the trans clean, I get a good view. Still, I'll check again when I get it up in the air.

BTW, sorry about not answering more quickly. We have had internet problems since Michael came thru. Again, appreciate all the answers and help. Thanks! Ben

 

[CBODY67]

If it tends to appear after the car has sat a while, consider that when the torque converter stops spinning and the pump ceases to pump, the fluid "inside" of the trans will return to the pan area. Some through the trans filter draining back and such. There is supposed to be a "drain-back" valve for the torque converter to keep it full with the engine stopped, but if it did, then you could fire the engine and immediately put it "D" or "R" and it would move immediately, more like a GM THM350 or similar. In other words, atf level would be above the pan gasket rail and closer to the shift shaft seal and the neutral safety switch. The torque converter nose/front pump lip seal, when it leaks, will "spin" to the edge of the converter if it doesn't drip straight down, by observation.

Just wanted to mention the dynamics of why it might not leak when running.

CBODY67

 

[70bigblockdodge]

Left side leaks are also from shaft seal or lines.
I have always had good luck with glueing the gasket to the pan with the yellow snot 3M weather strip adhesive, this is tough to get the residue off in the future. Glue it on lay it gasket side down on a flat cardboard covered surface. Place a heavy weight on it and let it sit overnight. A thin bead of rtv on trans to gasket side and snug it down.

 

[Lefty71]

It looks clean and therefore EZ to diagnose. If it only leaks after sitting a while, just wait for it to get started, then get under there with a flashlight and some brake cleaner and a rag and look for it. I don't mean to sound so abrupt, but sometimes that's all it takes. In your case, you may need to drive it a bit to warm it up, then bring it home and put it up on 4 blocks/stands so it'll be still level and easy to slide under there and start hunting a few days later. Good Luck, Lefty71

 

[1970FuryConv]

This subject has been covered here, a lot of the guy's recommend this one.
Mopar Performance 02464324AC: A-727/A-518/46RE Oil Pan Gasket Molded Rubber - Re-Usable | JEGS
With some searching you can find it cheaper than Jeg's

How much longer would my mounting bolts need to be? 1/8"?