How long have you had the car? Have you ever done a gearbox service? Where are you located?

 

I've had the car for a year now, and have not serviced the gearbox, and probably doubt it has ever been done.

Forgive me if I sound rude, it is not my intention, but I am pretty sure the gearbox is dead, and I am aware of the likely reasons why it is dead. If there is a possibility that changing fluid and filter will bring it back to life and save me £1000+ in swapping it out, then I am all ears, but I think it is unlikely at this point.

But rest assured, if/when I swap the gearbox, that will be TOP of my list!

 

It wouldnt hurt to slowly undo the drain plug?

 

Whats the cars mileage?

 

the car has 135,000 miles on it, worth probably around 4-5k in running order, so a new/rebuilt box is out of the question. I will loosen the drain plug tomorrow, but I'm not sure what I will be looking at. If the gearbox is dry, then It's going to be screwed, since there has not been a sudden leak. If some comes out, I do not know that it is the correct level, or contaminated etc.

Several people have mentioned this, and I don't have a problem looking, but is it going to be helpful? If I can change the filter and oil it will be much cheaper than a new box, but I cannot justify throwing £200 in parts into the car and then still have to swap the box out. Certainly if I can get a good used box, I will be servicing it as a priority!

 

You are right about firing the parts cannon and wasting £200. However, if you open the drain plug you can rule a few things out. Undo it carefully and see if any oil comes out. If none comes out then go from there. If some comes out you can firstly look at the colour and condition , that will tell you a lot. If you are carefull you can put the plug back in and wont lose much. If you drop the oil completely it will only lose about 4 litres. You can collect the oil and measure it and replace like for like. 4 litre would be less than £30 at mercedes. I am just trying to rule out the obvious at the cheapest way of doing things but its upto you. If the oil is nice and red and 4 litres or so comes out then you know its not that!
No you didnt sound rude either.

 

I would remove the level / fill plug rather than the drain plug. If the engine is not running, you should get a litre or two of fluid out so only release the fill plug until you see a little fluid and then screw it back in. Ideally, you should do this with the engine running as that will show whether the gearbox is correctly filled. If no fluid comes out, you could add fluid with the engine running until it trickles out. If the gearbox is very low on fluid, it might start working again without spending much money.

Richard

 

I didnt think they had a fill plug but i dont know on a 5 speed thats why i said the drain. As richard says a lack of fluid will prevent it working. We are only trying to go the cheapest route first!

 

What model is it, xk8 xkr. What year?

 

This is where I am struggling. I do not understand the mechanism whereby a car that runs smoothly suddenly loses all tractiion in this way due to a low oil level.

I will look tomorrow, but my optimism is probably better described as scepticism!

Having said that, if it *does* fix the issue, you all have my undying gratitude, and will be welcome to as many free pints as you can drink should our paths cross!

 

If its a 5 speed theres no fill plug or 6 speed.
only 4.2 has fill plug and its 02 so pressume 4.0 5 speed.
refill through gearbox dipstick tube if so.

 

The 5HP-24 in the 4.0 is known for torque converter failures. I suspect this is the issue, but it's just a suspicion.

 

The 5 speed and the later 6 speed in the N/A cars, both ZF transmissions, do indeed have fill plugs. Otherwise how would one fill the trans? Neither have dipsticks.

 

That is my main theory at the moment, given the sudden failure, lack of warning and no codes thrown when I put the car in gear and it does not drive.

I will check the gearbox fluids tomorrow and try to get my endoscope in behind the torque converter and see if that gives me any insight. A new torque converter costs about the same as a good used gearbox/TC so likely the outcome will be the same either way.

I was reading earlier about TC symptoms and one is vibration when driving steady at 1500 rpm. I have noticed this in the past from time to time, but it seemed to come and go with issues I have been fighting on the intake, so I didn't give it too much thought. Maybe it was an early symptom, or maybe unrelated, but I do think my issue right now is a total failure of either the TC or something else close to the input side of the gearbox.

 

Not sure about your side of the pond, but here there are some good torque converter rebuilders and it's far less expensive than a replacement trans. While you're at it you may as well install the Transgo pressure valve fix to try to save your A drum, if it's still intact.

 

A rebuilt transmission will be more than the value of the car, and fitting on top of that.

I am thinking of a good used gearbox/TC to swap in. Cost is still appreciable but cheaper than a replacement car! The gearbox I have been looking at is around the cost of a rebuilt TC. Labour is about the same for gearbox or TC swap (pretty much the same work involved in each).

 

The torque converter connects to the transmission in two ways. The outer shell of the TC has a hollow tube that drives the fluid pump of the transmission. When the TC is assembled to the transmission, the splines of the transmission input shaft engage with the rotor on the inside of the TC. At the same time, the hollow tube that drives the fluid pump engages with the pump in the front of the transmission. From what you have described, I would suspect that you no longer have drive to the input gear of the tranny. This could be a failure of the TC (rotor splines exploded can disconnected from the TC rotor vanes) or it could be an input shaft failure of the transmission where the input shaft became separated from the input gear. The lack of noise from whatever parts failed makes it difficult to locate without removing the tranny. If the tranny input shaft is still attached firmly to the front of the tranny after removing the TC, then it is most likely a failure in the TC.

 

Thanks for the reply, and thanks for taking the time to read the symptoms I was describing, I don't think everyone has!

My strategy at the moment is to swap in a used gearbox/TC. Most of the labour involved is there just to investigate, and the cost of a new TC is about the same as the gearbox/TC combo so might as well swap the lot out, then carry out a post mortem on the dead one, see if anything can be recovered maybe. I have an endoscope camera which I am going to try looking up the gearbox side of the TC without removal, but I am not at all sure that even if I can see up there I will see anything useful. Maybe if the shaft out of the TC is turning it proves the gearbox is bad, but it will make no difference to my end approach.

 

I had my torque converter fully rebuilt by these guys for £350 inc vat and collection/delivery: https://www.sussexautos.com/

I can see the appeal of fitting a used one, but what if that fails in 3 months? Sussex Autos offer a Lifetime Warranty.

 

A camera looking at the TC in the car would not see the input shaft to the tranny even if you had a fully transparent transmission housing. The tube that is attached to the TC housing and drives the fluid pump will completely block the view. And it is a very tight fit in there. The TC fits very close to the front of the tranny which has the fluid pump right there in front. Automatic transmissions are all pretty much all the same. The fluid pump in the front with the input shaft going through it to the first stage planetary gears. Replacing both the TC and the tranny is always the safest bet when the tranny or TC has failed because they share all the fluid and any metal particle debris is almost impossible to remove without major work.