Can headers passing too close to a tranny pan cause a tranny leak (heat damage to gasket)?

[coach2ma]

Hi, folks.

Does it sound possible that headers that pass extremely close to a tranny pan could possibly ruin the gasket and cause leaks via heat damage? There is little clearance (perhaps an 1/8th of an inch at best) between the header and the front left corner of my tranny pan (front left if you are facing the car) and that is exactly where my tranny fluid is leaking out of my pan. The car drove fine with no tranny leaks for about the first 3 weeks of short usage after install of the headers (an hour or two of light driving each time in Northeast spring temps). But after one long cruise that lasted all day and was more than 100 miles of driving, the next time I went to the car after parking it that day there was a puddle of ATF4 under it. Since then, it pushes out better than half of what I re-add during each drive (about 3 short drives since). I checked the tightness of the pan bolts, and while they did need a little tightening, they weren't particularly loose. After tightening, I re-added fluid, but it made little difference and the leak appeared in the same spot on the pan, almost immediately. I assume the gasket must be compromised (though it was not old)....could it be the heat proximity? Change the gasket and get some (really thin) heat shielding to try and wrap the header in that area, perhaps?

 

[1970cat]

could be someone pried on that corner of the pan, bending it while changing the fluid.

 

[coach2ma]

could be someone pried on that corner of the pan, bending it while changing the fluid.

Nah, fluid had never been changed yet.....the tranny and headers had only recently been installed new and driven only a few times before the leak appeared.

 

[saforwardlook]

If the puddle is in the vicinity of the left front of the trans pan, it is most likely the selector shaft seal that is leaking. It is a quick fix that David can do without taking the pan off again.

 

[Big_John]

If the puddle is in the vicinity of the left front of the trans pan, it is most likely the selector shaft seal that is leaking.

^This^

I don't know if the headers would get it hot enough to ruin the gasket... But that close isn't good either. It might be worth at least wrapping the header with something to insulate it at that point.

 

[CBODY67]

What brand of header is designed to fit that close to any part of the automatic transmission?

I believe the OP stated the "lh frt corner of the pan, standing in front of the car", which would mean "passenger side"?

At this point in time, only speculation of a crispy-crittered corner of the transmission pan gasket. Once fluid starts to wick through the gasket, it will not stop. Only a new, fresh quality gasket will stop the seep.

As to the header issue, two possible fixes. The easiest one would be a ThermoTec wrap of the header area. Using a thin metal "shield" on the header will only get hot with the header and radiate heat. The heat insulation wrap of that area will contain the heat and not radiate it to the same degree.

A more-labor intensive situation would be to get some bolts to replace the existing pan bolts on that side of the pan, but bolts with studs on top of them. Some flat washers, too, for the new pan bolts. Then a roll of 3-4" wide roof flashing metal.

With the new studded bolts and flat washers replacing the existing pan bolts, then measure and cut a length of the flashing appropriately. Put a 90 degree bend on the bottom section, then drill holes for the studs to fit through. Then install the flashing onto the studs (using more flat washers between the nuts for the studs and the flashing/shield).

IF you really are industrious, you can get enough of the heat wrap and wrap each runner on the headers from the flange to the end of the collector. I saw several sets of that at Mopar Nats years ago. It looks neater than cooked header paint and it's less expensive than ceramic coating, but takes time to do it right so it stays put. and looks good.

Just some thoughts,
CBODY67

 

[thethee]

Might want to check out the dipstick tube o-ring also

 

[coach2ma]

Thanks all.

My brand of header is TTI (fit for C body), tranny is standard A727 (year-matching 66, but fully rebuilt, with upgraded spline).

My first plan of attack was intended to be what CBODY67 says above: heat wrap, plus new gasket.
(With also a check of possible other culprits like seals, etc).

If plan A doesn't work, then I will get more involved.

 

[LocuMob]

Thanks all.

My brand of header is TTI (fit for C body), tranny is standard A727 (year-matching 66, but fully rebuilt, with upgraded spline).

My first plan of attack was intended to be what CBODY67 says above: heat wrap, plus new gasket.
(With also a check of possible other culprits like seals, etc).

If plan A doesn't work, then I will get more involved.

I have tti headers and have no leaks on my transmission pan. I agree it's probably the selector shaft seal.