Gearbox fault wArning

[Bootneck]

Just started the car after leaving it parked in the garage. I had deliberately left it in neutral. When I started the car I moved the gear stick to park and as I then went down to drive via reverse it made a clunk and the gearbox fault warning came on. It went backwards ok but would drive forward. After letting it warmup I switched it off and then restarted. It worked ok then with no fault warning. Obviously I’m concerned it may fail when out on the road. Should I not leave in neutral plus also should I let it warm up a bit after a long lay up.
Thanks mike

[Astromorg]

First thought is that it could be a fluid level problem, but if you could put a scanner on it and check for an appropriate fault code that would be a big leap forward. Any sign of leaks? Has the fluid ever been changed? Mileage? Could you do your own fluid change, with guidance if required?
Also model year and engine would help. If you put the details in your signature block it's there for permanent reference.
There shouldn't be any problem using the N position as you did.

[Bootneck]

Hi, thanks for your reply. Sorry I’ll put details in signature block next time, where is the signature block.
Anyway the car is 1998 4.0l convertible xk8.
I’m afraid I don’t have a scanner to plug in and I’m not that skilled at changing the fluid if it means lying on my back under the car, I am in my 70s.
However when I bought the car last year it had 94000 on the clock and I took it to a garage owned by a member and he give it a complete service including replacing the gearbox fluid. It’s since done about 1500 mls and was laid up in my garage since October 2019. There is a very minor leak, but it was only about a teaspoon amount.
It was due to go back to the garage fora new exhaust but that has been postponed due to the present lockdown. When it does go in I’ll get him to check the fluid level. Is there a dipstick that I can check the level with.
Thanks again, mike

[davidr]

Hello Mike - that sounds quite similar to the issue I had with my XKR. It started fine but when I put it into Drive it would go with a clunk and the Gearbox Fault warning came up. In my case it turned out to be the linear switch that needed to be cleaned up and re-aligned and its been fine since.
I'm not sure whether you have the same setup on an XK8 but the issue may be electronic. Do the lights for each position marker illuminate correctly as you change through the positions? (ie P, N, R, D).
As for a dipstick, I'm afraid your car doesn't have one for the gearbox which is a very poor piece of design I think. I'm in a more fortunate position in that my 4.0 XKR does have one as it uses a more robust Mercedes gearbox and not the ZF that you have.

[Bootneck]

Hi
Thanks for that I’ll pass that on to the garage when I can eventually get it in.
Cheers
Mike

[Andy P]

Hi Mike,
Although I'm sure your garage is very competent and with him being a member as well it should be ok,but still might be worth mentioning if he used the correct oil and followed the correct refill method(Very Important).
I'm in no way implying it is a bad garage but I've seen it happen so many times before and cause problems later on.
Even from garages that supposedly specialize in gearboxes.Then you get "Well I never knew that" .
The part people seem to have trouble with is getting the temperture of the oil correct(ie 30'C=Max 50'C=Min).
So your looking at getting to the correct level at around 30'C for the most accurate result.
Here's a link to the correct procedure,it is for the XJ range but it's exactly the same as we use the same gearbox.
https://drive.google.com/open?id=1QLfQy ... vcwXRcQS3g
You can download and then print the pages that refer to refilling.
The correct oil is Mobil Esso LT 71141 Synthectic ATF or at least one that meets the same spec.
You could also ask the garage to check the rotary switch(drivers side of gearbox) and the selector cable(passenger side of gearbox).The bolts have been known to come loose so worth checking.There is also a 10-way connector with flying lead which connects the
rotary switch to the engine management harness. The connector is retained on a multiconnector bracket bolted to the transmission
casing/torque converter housing joint.
Might be worth disconnecting and giving it a spray with electrical cleaner.
After all it's been under there for over 20 years
Hope you don't mind me mentioning all that.
Take care in these unusual times were in at the moment and keep us updated with what happens if you can.
Once were out of lockdown that is.
Good luck.
Andy

[Bootneck]

Thanks Andy
I’ll speak to them once I can get the car in.
Cheers