Just got a 1973 240Z w/automatic... trying to replace all the fluids, so I thought I would drain the differential and refill this afternoon. Had no problem draining (once I got the plug unsiezed), but the filling is a problem. Is that stubby plastic fill plug on the top of the "diff" really the inlet for the new oil? If so, how does one overcome the narrow clearance and gravity to refill??? The access is so limited, I'm not sure if I can even get a tube in there to pump it in...

No the plastic thing is a vent. The fill plug you will find behind the moustache bar. Sorry. You might be able to pump oil in with a little pump used to fill the out/drive on a out board on a boat set up . They are cheep . That is if you can remove the fill plug . I changed mine before I installed the diff. Gary :knockedou

The fill plug is right above the drain plug. The white plastic plug on top of the diff is the vent.

Hi Mike:

Sorry you are having this problem... but it's just another learning opportunity now - how lucky can a guy be?..

.... and so we learn that we should always remove the Fill Plug FIRST.... only after that, should we ever remove the Drain Plug..... rear end or transmission...

Absolute worst case (and I've been there a couple of times) - you have to remove the mustache bar and then remove the rear cover... So you'll need a new cover gasket most likely...

Once you have the rear cover off - you can clamp it in a vise, then you can heat the area around the Fill Plug with Propane Torch (both inside and outside surfaces) ... and break the Fill Plug loose.

Make sure you put a little anti-seize on both steel plugs before you reinstall them in the aluminum cover...

good luck

Carl B.

Thanks guys... and Carl, what is the "best case"...??? The "worst case" sounds like a pita to me. I can't believe there's not an accessible fill plug. I though my MGB was bad...

Thanks Vince. I see it now. Wow, that's about impossible to get to... looks like the plug takes a 17mm wrench...

Thanks guys! I was finally able to get the fill plug out. A well-fitting 17mm wrench and a b.f.h. finally persuaded it to turn... really siezed. Filled it with Castrol Hyploy C using a little $5 pump I picked up at O'Reily's... worked great! So, next, on to the transmission fluid. Guess I'll find the refill inlet BEFORE draining this time... right Carl???

Thanks again.

automatic tranny fluid is filled where you check it. Unless you go to a transmission shop have have the transmission flushed of all the old fluid.

Thanks Darrel. That's what I thought, but the differential fill plug experience has me a little gun shy...

Hi Mike:

Sounds like you found the best case - that being that the fill plug is still square enough to get a tight fitting wrench on, and then break loose with the application of sufficient dynamic torque. (I'm a big proponent of using a large brass hammer when necessary;-).

Actually, I can't remember the last time I found a fill plug that wasn't all but completely rounded off. I now keep a few new ones on hand.

As many here will attest - the use of Kroil Oil and Time - will also work wonders on any threaded or slip fittings that have frozen themselves in place. Kroil Pentrating Oil isn't real easy to get - as you have to order it on-line and wait for it to arrive at your door. It isn't cheap either, but it's worth it's weight in gold when you need it. Look for Kano Labs on line... Given the shipping costs I now order at least three aero-cans at a time. This year I ordered a case and give some as Christmas Presents to a few guys. I know they won't really appreciate it, until they put it on that first rusty bolt or screw they are trying to remove...

I will mention also that these plugs when new, with the square external heads are in effect Pipe Plugs. As such, when they get too rounded off to hold a standard size wrench, your next best tool is a thin Pipe Wrench, aka a Monkey Wrench (thin is a relative term here)..It will tighten down on the plug as forced is applied (if you put it on the plug in the right direction:-) .

Enjoy that 240-Z ..... there are really very few things on that car that the average guy/gal can't fix themselves.

FWIW,

Carl B.