[AllanC]

I decided to drain the fluid and replace the filter on the 40TE automatic transaxle on my 2003 Neon. Problem is after careful draining ( I let the transmission drain for 28 hours) I installed a new filter. I cleaned the flange of the transmission pan, applied a rubber gasket to the pan with RTV sealant on both sides of the gasket. I let the RTV set up for about 10 minutes and then installed the pan. I torqued the pan bolts to about 100 inch lbs. Service manual suggest 165 inch lbs but I did not want to over torque.

Installed appropriate amount of fluid and after driving to get transmission thoroughly warm, I have a leak a the lowest point of the transmission pan flange and between 2 center bolts. Leak is in the gasket to flange area and not around the bolt heads. I always have trouble of getting a good, leak free seal with any automatic transmission pan on a Chrysler vehicle.

The problem is that I think you could let this vehicle sit 10 years with the transmission pan off and it would still slowly drip fluid from the lowest area of the pan. Dripping oil gets on the pan flange and sealant and prevents a good bond to the transmission case from forming.

The fransmission pan flange edge is straight and the bolt openings are not deformed. Is there a better type of sealant to use other than RTV?

 

[dana44]

RTV is the best stuff to use, but cleanliness and flatness is always top priorities. Not sure if you have a steel or aluminum pan on your Neon, but checking for straightness is always a plus. Any time I have a pan and a gasket surface, I always check it with a crosshatch of sandpaper to ensure it is in fact flat and no high spots (which happens mostly with metal pans), and at the same time, will dimple all the holes outward to prevent leaks, works every single time. At the same time, aluminum and metal bolts can easily, if the fluid has been changed a time or two, pull threads outward a little bit, enough to make you think the bolts are tightened properly but really aren't. First thing I would try in your case is tighten the bolts to what the book says, 100 inch pounds is less than 7 lb foot torque, which may be just a little bit on the light side, 165 inch pounds is a little more than 10 lb foot torque, and you could actually safely go up to 12-13 lb foot torque safely.

 

[Oklahoma Wolf]

I've always gone to 165 inch pounds on these bolts - it's never been a problem, unless the threads were already stripped out.

 

[fnkychkn]

use RTV specially formulated for ATF. ensure all mating surfaces are clean and dry. toss the gasket and torque to spec.

 

[ImperialCrown]

Agree.

 

[AllanC]

use RTV specially formulated for ATF. ensure all mating surfaces are clean and dry. toss the gasket and torque to spec.

I would assume that the specially formulated RTV is aerobic which means it needs air to cure. I am definitely sure the problem is that lingering drips of fluid from the internal parts of the transmission cover the RTV on the mating surfaces and prevents curing. How does one overcome this problem? Any repair facility that removes pans and drains fluid cannot wait days / years for all the dripping to stop.

 

[Rickorino]

I assume that you checked the pan with a straight edge. I would never use RTV on a gasket. Maybe permatex. That rubber gasket is all you need. Transmission shops never use anything on a pan gasket. The RTV probably never bonded and could be causing the leak.

 

[AllanC]

The RTV probably never bonded and could be causing the leak.

I agree that in the leak area at the lowest section of the pan, the RTV never bonded / cured and this is the source of the leak. Along the sides it cured and there was no leak. When ever I have tried to use a rubber pan gasket alone to seal the pan, it will leak despite all the hammering and pounding on the pan flange.

I would never use RTV on a gasket. Maybe permatex.

Permatex is a particular brand name of RTV so it is the same thing???

 

[John Wood]

I assume that you checked the pan with a straight edge. I would never use RTV on a gasket. Maybe permatex. That rubber gasket is all you need. Transmission shops never use anything on a pan gasket. The RTV probably never bonded and could be causing the leak.

I never use RTV either because it is a great lubricant when it is wet. If you use it on a rubber gasket, the gasket will slip a little when you torque the bolts and then you may have a gap, followed by a leak. Some gaskets are just made to go on dry (i.e. all Felpro Perm-A-Dry) often the instructions say to use no sealant. For transmission pan gaskets, I clean the pan and rails with Scotch Brite and brake cleaner and just use the rubber gaskets dry. I don't have a problem with leaks and it sure makes it very simple to R&R the filter, fluid, and gasket the next time.

As a side note, you can loosen the valve body holding bolts and dump a lot more fluid. That will help slow the fluid dripping, but probably won't completely stop it.

 

[AllanC]

I finally was successful in installing the transmisison pan and it does not leak. I had to jump through a lot of hoops but this is the procedure that worked for me.

I purchased Permatex sealant form-a-gasket for automatic transmission pans. It is supposed to be formulated to withstand the additives in automatic transmission fluid. Item # 81180.

I then raised the right front wheel about 4 inches higher than the left front wheel. I got more fluid to drain from the transmission. I then lowered the right front wheel to a position about 4 inches lower than the left front wheel. I got more fluid to drain from the hidden cavities of the transmission. I then returned the vehicle to a horizontal, level attitude. That stopped the persistent drip that was running onto the flange mating surface of the case.

With all mating surfaces cleaned I applied the Permatex sealant to the transmission pan and installed a gasket. I placed all bolts through the holes and gasket to insure proper alignment. I let the pan sit for several hours to allow the gasket, sealant and pan to bond well.

I then applied sealant to the opposite surface of the gasket, installed the gasketed pan to the transmission and torqued the bolts to 100 inch pounds. This is less than the 165 inch pounds torque indicated in the service manual but I did not want to risk stripping the threads in the aluminum case. The extra thickness of the gasket means that not as many of the threads on each bolt would be engaged with threads in the case and I was paranoid about stripping bolt holes in the soft aluminum.

I then let the pan sit for 4 hours so the sealant would have a chance to cure and bond the aluminum case to the pan gasket. I then added fluid and no leaks. Vehicle was driven 100 miles today and there is no leak at the pan.

The real break through for me in solving this leak was getting sufficient fluid drained from the hidden cavities in the transmission so the sealant could cure and bond over a few hours time and no fluid would leak onto the sealant and stop the curing process. Also bonding the gasket to the pan first prevented the gasket from squeezing and moving when it was mated and torqued to the transmission case.

 

[dak4x4]

Some people try to pry off the pan after all the bolts are out. This could bend the sheet metal. A better way to loosen the pan is to hit it sideways with a block of wood driven by a hammer.