~New member

[roosters]

Hello from up north, Banchory Aberdeenshire , I am on my 7th xjs and love them have downsized from a 1977 PRE he to 1986HE XJ-S V12, to a 4.0L facelift XJS, In the past also owned XJC also Daimler V12, My current XJS I believe their called early facelifts, sounds like my Wife! It has covered 44'567 miles and is as new condition.
Only problem although very expensive was due to lack of use, Or over use of Sport mode has been mixing of coolant and transmission fluid, ( Would like to warn other owners of this as I believe it is quite common and would advise of remote cooler for tranmission fluid before this happens) as had to replace gearbox and radiator in one go OUCH. Anyway What a CAR.

[dhdove]

Roosters

Hi and a warm welcome to the JEC XJS Bulletin Board.

It seems that you are a real enthusiast after seven XJS's!

Interesting comment re Sport mode. I drive in sport mode at all times (except during the recent snow when "delete first" got a try-out).
Why do you think that excessive use of Sport will lead to transmission cooler failure?

Enjoy your Forum membership and I hope to meet you during next season if you make the long trek south to one of the Club Rallies.

Regards
Tony

[PaulE]

Hello and welcome. Looks like we have similar cars - mine is registered 1994 but has the AJ6 engine. It is on the cover of 'Practical Classics' this month (Jan) at present on the news stands along with XJS buyers guide within. Interesting problem which I have not heard of before. Keep us informed of solution.

[roosters]

Hi, thanks for the warm welcome,
I heard a loud noise from gearbox once i selected sports mode for the first time in this car, Discovered under hard acceleration in sports mode that the transmission cooler pipes was forcing transmission fluid under pressure into coolant within radiator due to corroded pipes within radiator then in turn coolant into gearbox, Have been told by jaguar specialist that this is quite common. I replaced radiator and gearbox and all is well apart from my wallet! Any other owners experienced the same problem?
(can,t wait for snow to melt)

[dhdove]

Roosters

Ah, I understand.

Cross-contamination between the coolant and gearbox oil as a result of problems in the rad is not uncommon, as confirmed by your specialist, as a result of corrosion of the transmission oil matrix piping.

Using sport mode simply holds each gear for longer in the rev range. It will not cause this failure. However if there is a leak it may be worse due to higher gearbox oil pressure at higher rpm's. Remember however that if it is leaking it is leaking at all times, in "normal" as well as sport and at all rpm figures.

NB What was the loud noise from the gearbox when engaging sport?

Regards
Tony

[roosters]

Hi, After talking with mechanic, We believe noise was a pressure release due to coolant rushing into gearbox when pipes finally failed (loud dull thud) . I managed another 20 miles before the inevitable happened. Was advised to fit after market transmission cooler separate to radiator to avoid this happening again, But preferred to keep my car original so fitted jaguar radiator. New autobox now fitted and old one in my garage , I opened it up for a look and brown sludge everywhere, I was planning to overhaul it in my spare time to keep for a spare as all internal parts and manuals are readily available from ZF................... to be continued. I believe same box as fitted to Ford Explorer and Range Rover also BMW 5and 7 series, XJ40, if trying to source used unit
Can only advise other owners to check under coolant cap for brown sludge if they suspect a leak or foam in transmission fluid, As was told by automatic gearbox chap.

Tip of the day: Just been told xjs brake pads are same as used in Renault master van , I wonder the difference in price?

[MARKPEARSON]

Hello Roosters
You are not alone with this the £2k+ bill still haunts me, but I did fit genuine Jaguar radiator and full gearbox rebuild that was in 2004.

Am I right in believing that the oil cooler for the gear box within main radiator is there to warm up auto transmission fluid a bit quicker when cold as well as cool down when hot ? so fitting an external cooler may not be the best thing to do.

Like yourself I like to keep the car as original using only genuine parts where possable.Having said that I refused to pay the £175 per damper for rear shocks and bought a set of spax for about one third the cost and these have been fine.

Best Regards Mark.
And welcome.

[poprivet]

I wonder if the heat-exchanger pipe within the radiator fails due to corrosion by the coolant or pressure from the gearbox fluid?

With engine running, I would imagine the oil pressure would exceed the coolant pressure forcing oil into the radiator. On stopping the engine, the water would be forced into the gearbox. Either way... nasty!

BTW, hello Rooster and welcome. Do you know for certain if the coolant was changed correctly and regularly before the failure?

[extratime1983]

This is interesting. I have a bill in the service history I received with the car. Goes as follows:-

Remove, recondition and refit automatic transmission after coolant contamination through faulty radiator.
Fit air cooled oil cooler system for the transmission so that the problem cannot occur again.
This cost the previous owner £2,683-83
Does anyone else have air cooled transmission?