Jaguar XJS Automatic Transmission Start-up (after long sleep)

Jaguar XJS Automatic Transmission Start-Up

(after long sleep)

Welcome back! so you know everything about Starting up your Jaguar AJ6 engine already (or any other engine in the car having a century-long nap). Now it’s time to describe the same process for inseparable part of your engine – automatic transmission. This procedure is applicable to most cars with REAR WHEEL DRIVE from 70s to 90s, including infamous Jaguar XJS v12 – shot in the dash by Elvis Presley on many occasions.  

You won’t find any information about manual gearbox as the only long-stay issue with manual can be related to elements of clutch seized by rust (use wd40 via bell housing vents, lubricate master/slave cylinders).

You can always start your granny-tranny in regular way with consequences to follow in the future and spread over time. If you choose to follow my guide – you will probably save 50-100k miles on this first “innocent” turn of the ignition key of your “barn find” It is recommended to perform what’s below - between step 15 and 16 of Jaguar XJS 3.6 AJ6 Engine Resurrection Guide.

I would like to dismiss all the claims of “skilled workshop mechanics” related to described start-up process – being completely useless or not required. With single blast - to summarise their expertise with two polite sentences below:

You ninny wankers, you haven’t seen real auto gearbox inside over your entire careers starting from your apprenticeships, ending at Kwik-Fit. You may know how to replace it but you have no clue how it looks and what to expect after few years in storage - you are useless outside of you box.

Returning to the subject - as you probably heard in technical literature – automatic transmission is a complicated mechanism, consisting of more than one part and covered with enclosure made of alloy containing Aluminium and Kryptonite to prevent even a Superman fiddling with it. What’s even worst – most of the parts inside are rotating! There’s more bad news, it’s no good when those parts are NOT rotating for a long time. Hence the guide below.


Chapter 1: Jaguar XJS Automatic Transmission - Design

To maximize efficiency of my time and to simplify assimilation of knowledge – for the purpose of this guide - let’s treat automatic transmission as solid element with prop shaft sticking out, dipstick pipe and drain plug. The main principles of operation are reflected by a number of four thesis below:



  • Thesis 1: automatic transmission is connected with the engine of your Jaguar XJs.
  • Thesis 2: magic is happening inside of your Jaguar XJS automatic transmission.
  • Thesis 3: magic from Thesis 2 is happening when the engine of your XJS spins, even if the car is parked/ doesn’t move. Even when the engine of your XJS doesn’t move and rear wheels are turning.
  • Thesis 4: magic from Thesis 3 needs magic potion to be executed. Magic potion is also known as “ATF oil”


Chapter 2: Jaguar XJS Automatic Transmission – Starting up after long time not in use

Time to start up your Automatic Transmission after long sleep. Usually required for the cars being in storage longer than 3 years, however environmental conditions can easily split that time in a half (the fact that engine was fired-up once per month – doesn’t count). Corrosion will attack ferrous and non-ferrous metal causing oxidation on the gearbox elements not dipped in ATF oil, Oxidation will cause high friction, scratches or even fusion in various assemblies. To avoid that you will need:

 

-       cheapest ATF oil: 15 litres (recommended cheapest semi-synthetic type, even if slightly more expensive)

-       whiskey: 0.25litre, shot glass and small funnel

-       large garden tray (min 40cm x 50cm, recommended 40cm x 100 cm)

-       rubber balloon and adhesive tape

The Process is pretty straight forward, hence worth doing. Don’t try to start or tow the car, just leave it as it is:

 

1.     Raise the rear of your Jaguar XJS to tilt the car forward 20-30 degrees. Use car ramps, axle stands, old sofa etc.

2.     Remove auto tranny’s dipstick and install small funnel.

3.     Place the garden tray under the gearbox, longer side aligned with the prop shaft axis. Make sure the tray is covering entire space under the gearbox – from the output shaft to bell housing

4.     Undo the tranny’s sump plug and drain old ATF oil.

5.     Pour fresh ATF oil through the dipstick’s pipe into the tranny - until it won’t take more.  Repeat until it won’t take more.

6.     Look under the car (with rear still lifted) – you should notice oil dripping from overfill pipe, in the place where prop shaft connects with transmission (and flooding the whole bell housing). If no sign of oil – repeat step 5.

7.     Grab bottle of whiskey and shot glass. Discard shot glass if you’re originating from Central/Eastern Europe

8.     Drink approx. 250ml of whiskey. Try to drink it as fast as possible (preferably no longer than 15 minutes) and proceed to step 9 immediately.

9.     Blow the balloon full and twist the neck several times approx. 1 inch from the inlet hole. Do not use any knots

10.  Slide neck of balloon over the dipstick pipe, secure with adhesive/duct tape and untwist it allowing he balloon to release the pressure. The air from the balloon should force the ATF oil down the dipstick’s tube. Top up with fresh ATF oil. Alcohol from whiskey, mixed with air in the will decrease the viscosity of the oil by approx. 0.0002% (per balloon) allowing hypothetical better penetration between the internal components…

11.  If you are abstinent or you are having serious health condition – skip steps 7, 8, 9, 10. It’s purely experimental.

12.  Leave the car with drip pan in place – overnight.

13.  Wake up, engage inertia switch, and run your engine on starter motor for 6-7 seconds. Repeat 3 times and go eat your breakfast.

14.  With both rear wheels up and free to spin (use jack stands, NOT two standard screw operated Jaguar jacks) make sure you have some space left in the dip tray positioned under tranny and the floor around your dip tray covered (spatter from running prop shaft), chock one of the front wheels in both directions.

15.  Start up your banger – if you’re starting the engine from long sleep – jump to Step 18 of Jaguar XJS 3.6 AJ6 Engine Resurrection guide before doing anything else and complete engine resurrection guide first.

16.  Let your XJS idle for MINIMUM 30minutes with tranny in Parked position. Do not change the gears. You should see nice, red waterfall under the car, in the area between prop shaft and rear end of the transmission. Waterfall will disappear after ATF oil will catch full temperature and expand – draining the excess from gearbox through the vent.

17.   

18.  Now it’s time to hold the brake pedal and engage the R on your gearbox selector. Keep your brake pedal pressed and release it after minimum 1 minute. You may hear odd strange noises and the waterfall will probably return for few seconds. Let it spin the rear wheels for a while the press the brake pedal again. If your wheels are not moving it simply means your rear brake callipers are seized (if so – there is no point of going any further. Simply press the accelerator pedal as see if you can force the rear wheels to spin under higher RPMs to confirm rear brake issue)

19.  Press the brake and switch to Drive, let it run/spin on idle for the next 15minutes – do not use accelerator pedal yet.

20.  It’s time to check how your tranny shifts the gears, and how well balanced are your rear wheels (expect vibrations – make sure your car is properly secured on stands). Press accelerator pedal, slowly. Observe RPMs to know when your tranny is shifting. Keep the range of 1200 at the beginning. You may hear clanks coming out from the gearbox. With AJ6 engine – your tranny will up-shift on idle first time and approx. at 50mph it will shift to top gear, there is no need to beat the speed record on stationary. Press the brake to down-shift and the accelerator to up-shift multiple time (you should play with it at least 30minutes).

21.  It’s not over yet. It’s time to replace your transmission oil – to do so you have two choices:

-       Static oil change: you will have to do it by dilution, several times filling up the tranny, running it with rear wheels up, over every selector’s position, then draining it, refilling, running again, draining, filling, running, draining, filling, running… at least 4 times. Each drain will allow to remove only 3.3 litres of the oil from the tranny, while total capacity is approx. 8 litres. It’s time consuming and low-risk method, however required litres of ATF fluid to perform correctly.

-       Dynamic oil change: easier, precise, quick, however carries a risk due to need of disconnecting both ATF fluid hoses entering engine’s radiator. Both unions ma be difficult to und and with heavy-handed operator can cause a big pain to your wallet (damaged radiator). From my experience – it was absolutely easy, easiest unions on XJS that I’ve encountered so far (wire brushed base threads from the top, sprayed with WD Degreaser, cleaned, sprayed with Liquid Wrench every day, four days in a row prior to removal). The method involved few meters of spare tube connected to each union, perfectly clean bucket, funnel, other bucket and at least 15 litres of fresh ATF fluid. Due to complexity and with appreciation of the fact, that if you are skilled enough then you already know how to perform this – this method won’t be described.

22.  After oil change (whichever you’ll pick) – top up the ATF fluid to the level covering whole bayonet plastic piece (with engine not running), Then start your engine, hold the brake ang go through each selector’s position. Finish with Parked position and top up gearbox oil slightly above “COLD” line on the bayonet. All done.


Chapter 3: ZF4HP22 Automatic Transmission – General Recommendations

Yes, the code above is the name of the auto gearbox mounted in every Jaguar XJS with 3.6L engine. Unfortunately, it was on board of the XJS only from 1987 to 1991.  Robust, bulletproof, taking abuse with smile.

 

If you are still unaware – exactly the same gearbox type was used in every BMW from 1984 to 1994, ridiculously with engine configurations starting from rubbish 1.6 petrol in 3 series, through the diesel models in series 5, ending on 3.5 Litre in top range series 7. Porsche 911 Carrera also received one! Now probably you already know – this is NOT a British Leyland design, but German – ZF stands for Zahnradfabrik Friedrichshafen. It can cope with 250hp easily with abuses included – will last a mileage of 200k miles without an effort. Remember gearboxes made by Rover? Falling apart, seizing bearings or shafts grinding the enclosures to finally stick through it? Well, this won’t happen with ZF4HP22. Only thing it needs it – fresh ATF fluid at correct level. Cheap spare parts which will be available probably until EV era closing in. From personal experience – I saw those in agonal condition giving all the sound of universe while running, with bits of friction plates in the sump pan…Still doing hundred thousand miles. Millions on BMW owners from those years can’t be wrong…

Recommendation 1: Keep the ATF fluid level to maximum

Speaking of the ATF fluid level – with ZF4HP 22 – it can’t be too high. Slap any single idiot telling you that your transmission will be damaged if the oil level is too high. Although the statement is true – it is not applicable to ZF4HP22. If it’s too high – you will notice drips from the tranny’s vent on your driveway, especially in a hot days and after using kickdown.

Recommendation 2. Keep the ATF oil fresh

It will take a wanker 30minutes to drain and refill 3.3-3.5litre of the ATF fluid. All you need is a drip tray and hex key from your bicycle to undo the plug (no need to raise the car, unless you’re a midget). Some ATF oils are coming with funnel in the cap… Do it instead of polishing your bumpers, once or twice per year. You won’t regret it.

Recommendation 3: Always measure ATF fluid level on hot and with engine running

This is the rule that I know since I was 17. However and as per feedback given – it is not that obvious these days, in fact this is not obvious even for these days workshop mechanics (modern auto transmissions usually have no bayonet). Always measure your ATF fluid level after long trip – not after full engine warm-up.

Recommendation 4: High speeds are best friend of your automatic transmission

With example of ZF4HP22 on the 4th gear all of the mechanisms inside of the gearbox are locked up and serve as the “drive shaft” between torque converter and the prop shaft. If nothing moves and everything spins together – there is no friction, no wear (I know, it's happening on 3rd gear, just trying to speed up all those XJS retard drivers...)

Recommendation 5: Oil filter of the automatic transmission

Yupp, your tranny has one, usually made from metal mesh or paper. Frankly, ZF4HP22 has metal one and it does not need replacement unless your gearbox is faulty or survived something horrible. To see if it’s in a good shape – you need to remove it (easy) prior to removal of the sump pan. Conclusion = just replace it with new one (£16)

Recommendation 6: ATF Oil types

There are plenty of topics across the Internet related to the best oil type to be used.

Some people are complaining that straight after oil change - their automatic transmission if not so smooth as it was previously – assuming that the oil type used is incorrect. To understand this sociological event – we need to go through the design of automatic tranny. It has several clutch units build in similar way as those in the motorcycles form 80s. Each clutch has a basket that holds friction plates. End of explanation.

Now, each tranny from 80s - 90s should have ATF Dexron oil inside. There are 3 Dexron types in our interest: Dexron I, Dexron II and Dexron III.

As you probably know – Dexro I was the first invented. It’s obsolete – regardless what the spec of your car says, it was replaced with Dexron II which is fully mixable with Dexron I. After few years Dexron III came out and replaced both older types. It’s better, it extends lifespan of your tranny. It covers it from deadly friction. It’s preserving seals and o-rings robustly.

Now, returning to the people saying that their tranny is not as smooth as it was after oil change – exactly, and that’s usually benefit. Shovel it into you head – smooth auto trannys are for luxury, rough trannys are for heavy usage. Less friction = longer service life. If your gearbox is acting rough after oil change – it’s because level of friction has decreased, clutch units are locking up faster, with less slip. Unless you’re comfort maniac – always use Dexron III.


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