I thought that I have an oil leak from tranny, because when I was under the car I saw pink droplets everywhere on and around transmission oil pan, and even on the cat.

However, whenever I pull the tranny'a oil dipstick, it always shows as more than way more than full. (Even after wiping the dipstick and reinserting/repulling.

Is it possible that PO (or PPO) overfilledthe transmission with oil?

 

Yes, test it hot and it should not be above the HOT mark on the dipstick. The easiest way to remove fluid, unless you have an aftermarket pan with a drain plug, is to remove the modulator and let any excess fluid out of it's hole.
You could also have leaks afterwards though, if the gasket is failing.

 

If the gearbox was losing fluid could you say <always more than half way full> ? , so I would not be sure it's the gearbox .
I would be looking at the PA steering fluid.
If it is this , look at the return pipe , this will only dump fluid after 'use' so it can go undetected for months.
This pipe is totally inaccessable , under the left hand (B bank) side of the engine.

 

Without meaning to be snide or disparaging, you do have the engine running when you check the tranny fluid?

The torque converter can drain and give a false overfill reading if the engine is not running.

 

I think this is somewhere out there, but just in case.

Checking the transmission fluid in a TH400 in a Jaguar XJS.pdf

I also agree with the steer fluid via the return hose, and/or the cooler fiasco, being the culprit.

The RHD is a snap to replace, ha.

 

Duhhh! I was checking it with engine not running! (It works for the engine oil, so it did not cross my mind about false readings on transmission oil if engine is not running!)

So, I read the instructions from Grant and checked again.

Now it shows that I am running low on transmission oil! The reading is well below L on the Hot side. (This actually makes more sense, because as I mentioned already I suspect that transmission oil is leaking slowly. I see pink droplets of tranny oil underneath.)

I assume I can top it off through the same tube (where the dipstick is)? Or is there a more convenient location for adding transmission oil?

 

Well done.

You need a drink, SERIOUSLY.

YES, topping up via that same dipstick tube, and I failed to mention that in the write up, as I assumed that was a given, oops, so that write up is now corrected, thanks.

Convenient, hell yes, you want to do this on my S Types, all from under with a thermometer, and LOTS of strange words uttered.

 

I added ATF oil, and it looks like I might have overfilled it. Given how low the oil mark was, I thought that it is about 2qts short, give or take. So, I added 1.75 qts to begin with. Looks like it was too much

 

So what.

The TH400 is NOT fussy with oil or its level. You need to be about 3ltrs++ overfull before things get messy inside.

Drive it, you have leaks, it will settle. Mine ran 1/2ltr overfull for 10 years, and never had issues. The other one is about 1/2ltr under, it leaks if I fill it to the mark, and is happy, as am I. It will get fixed one day, maybe.

 

Thanks, Grant! I am not too worried. Given the thing is leaking slowly anyway, the overfill will likely take care of itself over time.

I was (secretly) hoping to see some change in behavior, which so far did not materialize

Sometimes my transmission shifts kind of rough. With a jolt. That's why I was looking underneath and checking the oil level in the first place. But looks like running low on oil was not the reason for rough shifting -- during a drive after filling her up, it still shifted roughly, with an occasional jolt

 

Nice try.

The TH400 has a vac modulator on teh RH side, forward corner of teh trans, jsut above the pan gasket line.

They jam, leak, get hissy. The plunger behind that modulator also jams in the valve body.

Remove that modulator, exhaust is in the way, but you will figure that one out, and then reach inside to withdraw the plunger, and ensure it slides smoothly in its hole.

Replace the modulator with the newer "compact" unit that is adjustable.

The vac hose may also be a tad suspect, so replace it.

Next is the transmission regulator, accessed via a tin cover on the RH side rear extension housing. They also jam, and stick.

 

I tried to take some pics while I was under. (It was quite tight, so pics are not very good.)

Here is a picture of RH side of the transmission. Where would that modulator be located?

 

Vrok
That is the rear of the tranny. The modulator is at the front, on the vertical RHS face. In these pics, in the one taken from below, it is the gold coloured thingy at the top right of the photo.
In the one taken from the front, it is on the LHS of the photo.
Notice my beautiful Moroso sump pan!!!

 

Greg, thanks for the pictures!

I must admit, morose oil pan is beautiful!

 

Good on ya Greg.

Taht is embarrassingly CLEAN, surely it has grubbied up by now?????, or are you secrectly cleaning under the beast, HA.

Still looks sweet to me also.

 

Clean no longer, those snaps were taken when I fitted it.