Transmission Seal Replacement


Introduction
Even though the complete procedure for overhauling the transmission is included in the official Classic Range Rover shop manual, I normally shy away from any problems with transmissions as being far too complicated for the home mechanic to deal with. However Todd Pfortmiller wrote in with his experience in solving (with help from his mechanic) a problem caused by failure of the transmission seals, and kindly supplied the following details for others to benefit from.

 (Photo at right: Todd's helpers on the transmission job)

Symptoms:
"Upon startup, the vehicle drives fine for a little while. Then as the transmission fluid warms up, after a complete stop Drive will not drive. It feels like a little lunge, but that disappears immediately. A quick manual down shift into 1 to engage the mechanical linkage (as I understand it), gets the beast going again. Up shifting 'manually' works fine, and even a severe kick down at highway speeds to climb an 8% grade is not a problem. This is what I reported to my Land Rover Master Technician, Rob. Luckily he's my good friend and he agreed to drive it one evening. He suspected the three governor seal rings RTC4660. These are not commonly stocked parts so a seal kit for the transmission is obtainable from some transmission shops, or if a helpful BMW shop exists, they use the same transmission in some applications.

Solution:
(This is intended as a general overview, so get a workshop manual before you attempt the procedure yourself).

"Not being positive that this is the problem, making this a bit of a research expedition Rob pulled both the transmission and the transfer case at the same time. Time pulling one or both being about equal, my benefit was that if this was not the problem after splitting the transmission and the transfer box on the bench, the way was already clear for a new transmission. This also allowed me to have the rear main seal on the engine replaced for about the price of the part. I was already in for a complete redo visit anyway (hoses, belts, etc.).

"With the transmission and the transfer case on the bench, Rob split the two by removing 8 bolts, and then removed the stub shaft via the bolt through the center of it. There are some other parts to remove with simple unbolting and the governor comes off. The three seals are now visible in machined grooves. One of my seals was in 3 pieces, another in 2 pieces, and the third was complete. This allowed the fluid to bypass the seals and the transmission could not convert enough line pressure into governor pressure to make the vehicle move from a stop when maximum pressure was needed. I suppose that if more of the seals had gone there would be trouble all around driving except when mechanically selecting 1.

"Since having all the new seals on the back end of the engine and transmission, the Range Rover no longer marks his turf in every parking spot. I have been on some challenging trail runs since and have had no further problems! Good luck and I hope you too can avoid replacing an entire transmission."

Parts Needed
Gasket, Seal and Overhaul Kits
Todd found the seal kit cost $150. FOr the adventurous, I found a complete Range Rover transmission overhaul kit is available from ExpressAutoparts.com for only $38, containing  Gaskets; Seals; O'Rings; & Sealing Rings. A Master Repair Kit for $72 contains these items plus Friction and Steel Clutch Plates, Oil Filter, Vacuum Modulator, Front Pump Bushing, and External Housing Bushing. For a job of this importance you might want to go with a Rover parts specialist; Atlantic British has a range of gasket and seal kits for this transmission starting at $119.

Complete Transmissions
If your problem cannot be solved this simply, do not despair as complete rebuilt transmissions are becoming more affordable. For example, Atlantic British has them for $3795.