1996 Explorer XLT: Big transmission leak

[jazzkeys]

Howdy, y'all,

My Significant Other (hereinafter S.O.) owns an Explorer with the 4.0l V6, RWD, and the 4R55E transmission. In the last several years, maintenance has been sporadic at best. I've taken over, and the Explorer has been pretty reliable.

Toward the end of a freeway trip from near Pasadena yesterday, a very hot day (the thermo inside the truck read 96F), I noticed the odor of smoke. The S.O. was driving, and I asked her to pull over. Almost immediately, I noticed Dexron leaking under the truck. With the engine idling, I inspected the transmission dipstick. No fluid visible. OK; this is bad.

We were close to home so managed to coast the rest of the way. I raised the truck with my jack, secured the jackstands, and crawled underneath for an inspection. Dexron everywhere underneath, and it appeared to be dripping from the bell housing. Argh; I had hoped that it would be simply a leaking pan.

I visited the local Irish parts retailer and bought a filter kit and two gals. of Dexron. Haven't installed the filter kit, but topped up the transmission through the dipstick tube, and it took a whole gallon. Took a short test drive, and transmission seems to be shifting correctly. With the engine running, transmission in D, but brake on, I inspected the bell housing area again, and did not see any more leaking.

However, I found an article that suggests that the transmission may have overheated because the valve body thermostat may have been stuck, which pushes fluid past the front pump seal. Would a simple fluid and filter replacement prevent this from happening again? I looked at the S.O.'s maintenance receipts and didn't see any indication that the fluid and filter had ever been replaced, though the "Normal Service" maintenance schedule specifies every 30K miles.

Also discovered from the maintenance receipts that the transmission is a rebuild, installed by Aamco in 2003 for >$2400.00.

Bottom line: What's the cheapest way to make the transmission reliable again? The S.O. doesn't have much $ to spend on this.

Thanks kindly.

 

[PopRichie77]

First off the trans is filled with Mercon V and not Dextron. It's not very likely that the valve body thermostat valve stuck. If it failed the trans will over heat on any hot day on an upgrade when the torque converter is unlocked. When you replace the filter get MERCON V (5) to refill it and do a complete change. Instructions are here.
http://www.partshp.com/FluidChange.htm

 

[jazzkeys]

Thanks for your note, Richie. I miswrote: I did put a gallon of Mercon (as stamped on the dipstick) into the tranny.

Do you think that the fluid-and-filter replacement will be adequate? I haven't taken the Explorer to any shops yet, but I have visions of being told that the transmission must be replaced with a rebuild, for which the cheapest $ I've found so far is $1100, exclusive of labor.

Thanks much.

 

[PopRichie77]

Did the OD light flash when the fluid came out? If not I would try the filter and fluid, and see if it leaks again. Usually the fluid comes out the dip stick tube in these trans s when overheated not out the front seal. If it leaks right away the front seal is probably bad.

 

[jazzkeys]

Howdy again, Pop,

I had the Explorer transmission briefly inspected today by removing the starter. Lotsa fluid in the bellhousing, so the tech thinks that the pump seal is leaking. Otherwise, no visible wear or other damage. And the engine side of the flywheel is dry. He'll drop the transmission tomorrow and inspect the torque converter and fluid pump. The pan gasket isn't leaking, but I'll have the filter replaced, 'cause it probably has never been done. Tech estimates 4-5 hours of labor, and maybe replacement of the torque converter.

Thanks for your responses, and I'll keep y'all posted.

 

[kosakoskim]

Did replacing the front seal solve the problem?

 

[imp]

Really big leaks happen where 2 things are present: high pressure, and a constant supply of oil to the leak area: Front seal, cracked housing there, maybe, ......

Low oil pressure, sporadically present supply of oil: rear output shaft seal.

Even smaller leak: pan gasket, loose fill tube,.....

Pretty big leak, transmission cooler lines to front of vehicle: fairly low pressure, but constant supply of oil, while engine running.

imp

 

[jazzkeys]

Fixed; please see photos

Many thanks for your posts in reply.

Yeah; the input shaft seal had failed, so, after dropping the transmission, it was straightforward to replace it. At the same time, the tranny filter was replaced, as was the rear main crank seal. There was a trace of engine oil visible on the back of the block around the crank flange after the flywheel was removed.

I replaced the radiator several months ago, but reused the lower hose. I noticed that there was a slight leak where the hose was a bit deformed at the outlet, so the lower hose was replaced.

The invoice was $450, which was reasonable considering the time required to finish everything.

My only complaint was that the transmission was grossly overfilled by the tech. I checked the level with the engine idling when I returned to collect the truck, so had them vacuum out the excess Mercon.

Now, on to the next tasks: inop A/C, and those ugly old balljoints.

 

[jazzkeys]

H-m-m; about those pix. The "Insert Image" button only shows a URL field. Am I missing something?