Good day,

Gave my transmission a new pan, sleeve, lgf6 fluid.

Did it per spec getting to 40*C and filling till dripping out.

I noticed the fill plug is leaking some coolant overnight. I tightened it up some more, checked back the next morning, still the leak. Anyone every experience this?

Was considering putting the plumbers tape on it to snug up the threads. I really don't want to go through the refill procedure again. Figured I could jack car up on passenger side so fluid in trans is away from fill plug and give it a go.

Thoughts?

Thanks!

 

I don't recall if there is an o-ring behind that plug or not. If there is a seal, I would agree with jacking up passenger side while car is cold and swapping the plug. I would not use teflon tape or anything else on the threads (that might get into the trans).

 

I would replace the plug with new and ensure it is tightened to spec.

 

I just did a trans service on an X350 but can't recall whether there is an O-ring on the fill plug. The parts diagram does not show one. The part number for the plug is C2C38962.

If your exhaust pipe runs as close to the transmission as the ones on all the X350s I've serviced, you don't have room for a torque wrench, so I just use my cut-down 8mm Allen wrench to make the plug as tight as I can by hand. The torque spec is 35 Nm / 26 ft. lbs. +/- 10%, so if you're using an Allen wrench about 6 inches long, you can put 50 pounds of tension on the end of it, which is all many of us can manage while lying on our backs under a Jaguar.

If you're sure the plug is really tight but still leaking, your idea of jacking up the passenger side so the fluid will flow away from the fill plug should work. If the plug does have an O-ring, you may be able to find a suitable replacement at an auto parts store (it will be metric in both cross-section and inside diameter (I.D.)). If there is no O-ring, clean the area around the fill hole and clean the plug to be sure no grit is preventing the plug from seating properly.

If the plug just won't seal, while I can't argue with abonano's recommendation that you get a new plug, you may be able to resolve the issue by cleaning the threads on the plug and in the fill hole and applying a small amount of a suitable sealant to the threads. There is almost no fluid pressure at the fill plug, so any good pliable oil- and temperature-resistant sealant should work, such as Permatex Thread Sealant (either the High Temperature or High Performance version), Permatex Ultra Black RTV silicone sealant, etc. All are available at most auto parts stores. I would avoid thread lockers (Loctite) or rigid sealants like Permatex Ultra Grey, which could make future removal of the fill plug even more difficult than it usually is. Use a very small amount of sealant all the way around the last few threads near the head of the plug, but none near the threads at the leading end. You want to avoid the possibility of any sealant squeezing off the end of the drain plug into the transmission, where it could harden into a glob, break off into the transmission and work its way into the valve body where it could cause a serious malfunction.

To clean the fill plug, use any zero-residue solvent like brake cleaner, electronic cleaner, MAFS cleaner, acetone, lacquer thinner, etc. and allow to dry. To clean the threads in the fill hole, apply solvent to Q-tip swabs/cotton buds and carefully clean the threads repeatedly, then follow up with dry swabs/buds until they come away clean. Take care to leave no fibers behind.

Cheers,

Don

 

 

To my best recollection there is no o ring or washer that accompanies the plug. I would be cautious putting any sealant on the plug as it's not in the original design.

From my understanding the plug should be changed out.

Be sure to keep an eye on it with that o ring.

 

 

the green o ring crushes once it is used once. the directions for changing transmission fluid say to use a new fill plug. i looked at my old one and the new one, and it was clear that the thin green o ring squishes down once it is used. maybe someone can use a thicker o ring? the fill plugs are only $7-8 from the dealer, or $4 ish from zf (fcp euro, ctsc, etc) so maybe thats worthwhile doing rather than a thicker o ring?

with the car off, i think lifting the passenger side by itself, probably won't be enough because its 1-1.5 quarts in the transmission over the fill plug when the car is level. you probably will need to lift the passenger side, get your fill plug ready and tools set up, then have someone else turn on the car and right away change the fill plug (so the exhaust doesnt get too hot and burn you). if you do it within 1-2 minutes of the car being on, it shouldnt get too hot.

 

I don't understand the concern people have for burning themselves on the exhaust, I found it very easy to get under that with the car on ramps and do the fluid/change fill. I guess I am skinnier than most haha

 

Maybe your exhaust is routed a little farther from the fill plug than on some cars. On the 2005 XJ8 I recently serviced, the exhaust was only about 2 inches or so from the transmission fill plug. I use an 8mm Allen wrench that shortened specifically for this purpose, and I have learned how to deal with the narrow clearance, but for many first timers it's awkward and easy to be burned by the exhaust when you're opening the fill plug with the fluid at 40 degrees C and the exhaust much hotter than that.

Cheers,

Don