I have a 1987 XJ-S V12 with the 5.3L engine and the TH400 transmission. Of late the transmission has been misbehaving...won't shift when it should at times, and at other times it's OK. Investigating, I see that it has too much transmission fluid.

So, how to get some of it out to see if that helps.

My first thought is to run a small flexible tube down the measurement tube and siphon some of it out. I suspect the tube will need to be a bit on the stiff side to get it to go around the various bends.

I don't have the equipment to get the car up far enough to deal with the transmission mount and, this one having the stock pan there is no drain port.

Does this seem like a practical idea?

Thanks,
John
1987 XJ-S V12
70,000 miles on the odometer (if it hasn't been rolled back)

 

John,

First of all, are you measuring correctly when the gearbox is fully warmed up, engine running, cycle through all gear positions and then immediately check level?

Excess fluid is unusual. Have you or someone else topped up the fluid? When was it last changed?

If you don't know that it hasn't definitely been changed in the last 2 years / 5k miles, I would change all the fluid anyway, not just syphon a bit out. These boxes need good clean fluid.

And yes, you will be able to syphon a reasonable amount via the dipstick. Although ideally, I'd change the sump filter also. But even just changing the fluid is a good start.

Cheers

Paul

 

Excess fluid won't cause the trans to act up, but it will overflow out the overflow tube when exercising the car, like climbing a long hill at speed.

This is usually noticed by lots of white smoke billowing out behind your car as the fluid hits the exhuast pipe.

Doug

 

been there!! Freaked me out. Was like a smoke screen on pass side. I thought it was coming from exhaust.

 

I agree, a tad (a ltr or more ) over the full mark will do no internal harm.

Shifting issues is usually the Vac Modulator, OR, the Vac hoses to it, especially the 90deg elbow that is right near (too close) to the A Bank exhaust pipe. More common N issue than many admit.

Stale fluid, mentioned, will KILL any auto trans quickly. If no other way, syringe out what you can via the fill tube (done it too many times) and refill with fresh. Repeat after about 100miles, and keep going until what you syringe out is the same colour as what is going in.

The suction tube, filter to pump, inside the trans, has an o/ring at the pump, they crack and split, so the pump sucks air instead of fluid, OOPS. Quite common, and overfilling the trans by about 2ltrs is the simple yes/no test.

 

OK, well, guess I'll be using a syringe as suggested.

I'll have to do this with the car on a slight grade. So I can get as much fluid out as possible I'll want to park it with the fill tube on the downhill side. Does the fill tube go to the front, rear or middle of the transmission pan?

As far as measuring, the dipstick indicated well above full with the transmission cold. Since I can't easily get under it, I have the oil and filter changed by a mechanic (not a "quick lube" sort of place). My theory is that while doing the oil change somone decided to top off the tranny, went too far, and decided to keep that bit of information to themselves. Good help is hard to find :-)

Thanks,

John
1987 XJ-S V12

 

John,

Just put a thin tube down the dipstick as far as it will go whilst on the level and syphon out, BUT....

You must check the level first when fully hot and gearbox cycled. Checking it when cold is completely misleading and is not giving you an accurate position as to whether you are overfilled or not.

Good luck

Paul

 

Paul is right.

We were taught, big stick in those days, ALWAYS drive an Auto trans car at least 15kms, with as many gear changes as possible.

Return to the shop, level ground, leave it running in P, pull the dipstick, wipe it off, insert and remove in one fluid motion, read the scale, SIMPLE.

EXACT was not required, its not a science thing, its a level, and a mm or so either side was/is deemed OK.

Our teacher was worse than the Drill Sergeant in the Forces, and he was tough.

That fill tube enters the trans at the RHF corner, on teh top face of the casting that has the pan below, just forward of the Modulator.

 

Good stuff to know! Makes me wonder why they even put a "COLD" index on the stick.

I'll report back, and thanks to all for the responses.

John
1987 XJ-S V12

 

Including the "Cold" reading has always been a mystery to me. 'Tis nothing but a snare and delusion.

There are other Jaguar mysteries that make us wonder...or worse. Long, long ago I stopped trying to understand them. I just accept them as "interesting design features".

Cheers
DD

 

OK...I've used a syringe to suck out all the transmission fluid I can reach.

So, the question becomes...since the "COLD" index mark is unreliable...how much new fluid do I add?

Thanks,
John
1987 XJ-S V12

 

Most oil charts quote service refill qty.

I pour in 4ltrs (trans fluid down here comes in 4ltr containers), and then do the run up to basic temp in the driveway.
Run the engine, foot on brake, go to R, wait, go to N, wait, go to D, wait, then back to P and dip the thing.
Wait = about 15 seconds, I dont count, its just imbedded.
Somewhere between C and H is a guide.
Go for a drive, as mentioned, then check on the return. Top off about 1/2ltr at a time.

As Doug has hinted at, the marks are a guide, not a science.
When you look inside a Trans, you would need to be at least 5ltrs overfull before any rotating things get dunked.

 

Goo advice from Greg.

The transmission circuit holds about 9 litres in total but that includes torque converter, oil cooler and oil cooler lines.

In my experience on the 4 litre box you can drain a max of between 2.75 & 3.75 litres without removing the sump. Also fluid continues to drip down for many days after the initial drain, so try another syphon just before you do the fill.

Greg's advice of 4 litres initially is a good start point.

Cheers

Paul

 

Paul,

You been drinking again HAHA.

Could NOT resist that typo mate.

Old age, fair Mongrel.

 

Grant,

Apols! That's the problem typing it on my phone! I then couldn't see the previous comments but remembered it was definitely one of the "G's"! But obviously guessed at the wrong one!!

..Must try harder!

Paul

 

Maaaaate.

All good.

Fairly hard to tell us apart.

Good looking.
Drink whatever is open
The ONLY TRUE Jag is a V12, the rest are Wannabies.

But I digress, and GGG will get upset if we continue in here.

Life's too short mate, never worry about us.

 

We all know better than to worry about the Aussies!
If y'all guys is having trouble then the rest of us are DOOMED!!

 

I want to formally protest about point (1) above. This is terrible lie my friend Grant is putting about aided and abetted by Paul!
I am MILES better looking than he is.

Point 2 is true, but he is only relatively goodlooking while I am TERRIFICALLY so.

Points 3 and 4 is of course an agreed common factor between Grant and my handsome self.

 

OK if you say so (who am I to argue such a point, as I only have a ((shudder)) V8 Converted ((Mongrelized/Defiled)) Xj6?), but I will happily Drive the Wheels off my "Wannabe," smiling at admirers who give me 2 thumbs up until they pry my keys from my cold dead hand and cut my stiff corpse from the driver seat.

 

Well, I've added new fluid, checked the level when hot per suggestions above. Things are still strange.

The first shift point has moved up to 3200 RPM(?). Not a big deal if I just drove on the highway, but the engine spinning at nearly 3000 rpm down a city street gets a lot of attention (as if the car is broke).

When I manually shift into second gear, nothing happens, it just stays in 1st gear.

It still jumps around from gear to gear in an unpredictable manner.

The local transmission ships won't touch anything older than 20 years.

John's Cars has a kit to replace the TH400 with a used TH700, has anyone done this? Not sure I could do it anyway. I don't have the means to lift the car high enough.

Thoughts?

Thanks,

John
1987 XJ-S V12
about 70,000 miles