1994 T&C minivan, 3.8L, 2WD, automatic transaxle.
Family vehicle, maintained by dad (me), but dad doesn't drive it.

A few months ago I replaced the Trans fluid/filter/gasket and cooler hoses due to various trans fluid leaks. When I replaced the pan the first time Iused the black RTV butit refused to seal properly and after 3 tries I began looking harder at the manufacturer's tech bulletins: inthe end I found out that the manufacturer now reccomends a special (reuseable) rubber/metal gasket. Afterinstalling the gasketeverything looked tight and dry. A few days ago it was still nice and dry, then yesterday Inoticed that I've been leaking trans fluid again. The rear of the pan is all wet with fluid and about three drip 'sags'. (My term -a sagis a drip that has not dropped). The bottom of the pan looks scratched.
How possible is it, that the driver ran over something that inadvertently compressed the gasket to the point where it now has to be replaced. I can't torque the pan bolts any tighter because they are at the maximum torque setting now.

My current plan is to replace the gasket again, - If I do should I replace the pan too?

Is there any other trans leakproblems I should look into first before replacing the gasket?Any suggestions or recommendations? It looks kind of straight forward, but I don't want to overlook anything.

Thanks.

 

Tranny pan bolts are tempermental about torque. I always recommendyou torque the bolts to spec working from one corner of the pan to the next. Torque is usually 10-12 ft*lbs. (check manual)I'll torque them all to 8 and then final torque to spec. Also, if the pan bolt holes are dimpled, take a ball-peen hammer to them and bump them out flat. Most repetitive leaks are repetitive becuase the dimples that are created each time the bolts are tightened are not flattened when the gasket is replaced.

Keep in mind also that the pan is usually steel while the trans housing is aluminum. This means they will expand and contract at different rates. I always use RTV on one side of the gasket ( usually the pan since, if I have to redo it, I can scrape it off while standing at my bench instead of on the floor of the garage on my back ;-)). this ensures that as the metals expand and contract, it does not slowly push the gasket out of the space it is supposed to occupy.

good luck

 

Thanks for your reply JeepAndAVan I appreciate your input.

I've torqued the bolts in a criss-cross pattern using a gradual 3 step torquing method to 165 inch pounds as per spec.The OEM gasket costs about $30 and is made of silicone andhas flat metal o-rings for the bolt holes . I've never usedRTV with the silicone gasket because the Tech Bulletin (#21-05-99 Rev A) installation notes say to apply a thin coat of transmisson fluid to the oil pan and transmission case pan rails before installing. (and if the RTV sticks to the silicone gasket you couldn't reuse the gasket.)

Do you have anyguess as to why the trans fluidleak has ocurred so suddenly especially when the gasket has been holding up just fine for the past two months?( I have been under the vehicle numerous times for other repairs and I've inspected the pan often and have observed no leaks at all, it was always bone dry.)
If the leak is coming from another part of the transmission and running back to the lowest point it could seem like a pan gasket leak. ...besides the cooling hoses and dip stick where else could it be leaking from?

I hope I'm not overlooking something obvious.

 

Ithink there is a vent on the top of the transmission and I have seen leaks develop where the solenoid pack bolts to the front of the transmission. overfilling can casue the fluid to leak out of the vent. obviously, any leak will run down and drip off the lowest point which is that back edge of the pan. I woud suggest power-washing the engine/transmission at a car wash and then climbing under it when you get home to see if you can see the source.

FWIW, I never used the gasket and have not had any issues. guess I am lucky in that regard!

 

Thanks again JeepAndAVan,

I'll clean the trans and try and verify where the leak is coming from.

As far as RTV goes, I think it requires experience rather than luck in order to do it properly.

I've read different methods for using the black RTV...some say you should what a full 24 hours before torquing the pan down in order for the RTV to cure. I've cleaned the mating areas and immediately joined them together, I've waited an hourbefore joining them together... I don't know what the problem is with me and RTV. Whenever I torque the pan to spec, all the RTV squeezes out and it leaks or if I wait too long and the RTV sets up it splits when torqued. Some people say they don't torque it to spec but instead tighten the pan bolts a certain number of rotations, or one turn past finger tight. Also, with the front of the vanon jack stands the trans is not level and the remaining fluid never stops dripping downonto the back lip of mounting railand the RTV won't seal properly if the rail gets wet. After four failed attempts I gave up on RTV.

Although my present pan gasket is reusable, IF it turns out to be the gasket I will have to assume it got damaged somehow and willhave to decide if I want to try RTV once more (it would be cheaper)or buy another ga$ket. <never a dull moment for dad>

Thanks for the advice.

 

Just thought I'd post an update. After wiping down the tranny as best I could, I detected some fluid on the bottom side of a clamp for one of the cooling lines. On further examination (using a bright lantern) I saw a puddle of fluid on top of the trans in a body cavity. It was very difficult to spot even with a light; but it led me to the conclusion that one of the hose clamps had loosened up. After tightening the clamps the leak seems to have stopped.

If there is no more leakage I will consider this problem solved and I will not post on this topic again.

My thanks to JeepAndAVan for his advice and expertise.