[Phil1]

As it's 6th gear only/always, seems to me it must be a gearbox fault. Also doubt it's something an oil change would fix. If I had this problem and couldn't put up with it, I'd go to a gearbox specialist first.

Absolutely. Why bother going to the effort and expense of changing the fluid when it's highly likely it's going to get changed/rebuilt anyway.

 

[hamedhbb]

I haven't tried changing the oil and pan yet because I dont want to waste the money if it is not related to my vibration. Its another thing that I have not discounted though and will do it before I finally start pulling things to pieces.

I have inspected the engine mountings you mention with particular attention to the gearbox mount and they appear to be ok. I do own another XF with a similar drivetrain so may swap that gearbox mount just to see if anything changes.

You can visually check gearbox mount without removing anything. In worst cases, you should be able to move engine in forward, backward direction or even engine could touch the firewall.

if you clean the area properly, you could drain the oil to remove the pan and check the valve body and reuse the oil. This way you could things like swapping solenoids around and see if fault follows the solenoid.

it would be good to share a video of the judder you mentioned. Maybe others have experienced it to help you.

 

[gt40]

Problem is fixed. But not 100% sure what fixed it because I did two things. Firstly I changed the rear gearbox mounting with a new genuine part. The one I removed had seen better days. I then ran the car on the lift through the gears but the vibration was still there.

So feeling very despondent I decided to change the gearbox oil as the last resort before dismantling. I drained it and let it drip overnight (it wasnt too dirty surprisingly) and this morning refilled in accordance with the ZF procedures but using Ravenol 8HP oil and the vibration has gone.

I suspect the old oil was not doing its job efficiently which caused some vibration and the dodgy gearbox mount wasn't able to do its job correctly which then allowed the vibration to be felt.

Or maybe it was the swearing that fixed it. I dont know for sure but its fixed now and I can tell my gearbox supplier to put the replacement box back on the shelf.

Thanks to all for the suggestions and help.

 

[gt40]

A few of my babies.

 

[PeteA]

Problem is fixed. But not 100% sure what fixed it because I did two things. Firstly I changed the rear gearbox mounting with a new genuine part. The one I removed had seen better days. I then ran the car on the lift through the gears but the vibration was still there.

So feeling very despondent I decided to change the gearbox oil as the last resort before dismantling. I drained it and let it drip overnight (it wasnt too dirty surprisingly) and this morning refilled in accordance with the ZF procedures but using Ravenol 8HP oil and the vibration has gone.

I suspect the old oil was not doing its job efficiently which caused some vibration and the dodgy gearbox mount wasn't able to do its job correctly which then allowed the vibration to be felt.

Or maybe it was the swearing that fixed it. I dont know for sure but its fixed now and I can tell my gearbox supplier to put the replacement box back on the shelf.

Thanks to all for the suggestions and help.

Very good news, glad you got there 'cheaply'.

 

[JakeBlade]

Sometimes you just need to swear at inanimate objects to get them working again.

Glad you managed to fix it.

 

[cutlea01]

I'm quite amazed how many issues with an auto box are fixed with a fluid change. Logic would dictate that any particular issue wouldn't be the fluid, it'll either work or not work, but that's not my experience and you've added to it! Well done for a "cheap" home DIY self-fix.

 

[wilf]

Very good news, glad to read it.

Always like to see my "try the cheapest fix first" mantra working out in real life.

 

[ninjag]

That's good news.

 

[Rigger]

Sometimes you just need to swear at inanimate objects to get them working again.

Glad you managed to fix it.

We did that with a trainee once. It had the desired effect

 

[gt40]

Sometimes you just need to swear at inanimate objects to get them working again.

Glad you managed to fix it.

Choosing the correct words to use is quite important depending on the particular problem. Obviously the first few I used didn't have the desired effect until I dug deep.

Sorry i cant share them but I am sure you know what I mean 😁

 

[hamedhbb]

Glad it is fixed. How much oil could you take out of the box?

 

[PeteA]

Choosing the correct words to use is quite important depending on the particular problem. Obviously the first few I used didn't have the desired effect until I dug deep.

Sorry i cant share them but I am sure you know what I mean 😁

 

[gt40]

I got 3.6 litres out.

Not 100% sure how much I got back in due to some clumsiness and having a spill but I think around 4 and a bit. The level was definitely low which may have contributed.

 

[Phil1]

Certainly is low level.

I think 8.5L is capacity from empty, but 5-6 litres is usually how much comes out (Some left in the torque converter).

I'm surprised it didn't throw an error code, but I'm fairly certain it doesn't have a level sensor internally, probably just a simple pressure switch. I bet it was right on the limit and that one gear requires more fluid than the rest to engage fully.

 

[hamedhbb]

I totally agree. Did you check for any leakage around the cooling lines/connectors? Or around pan seal?

 

[gt40]

The car is as dry as a bone underneath. Not a leak to be seen. Perhaps it was low from a previous oil change that was not done correctly - the fluid was too clean to be original. Unfortunately the car had no service history when I bought it so cant refer back but I can see that it has been well cared for.

 

[ninjag]

The car is as dry as a bone underneath. Not a leak to be seen. Perhaps it was low from a previous oil change that was not done correctly - the fluid was too clean to be original. Unfortunately the car had no service history when I bought it so cant refer back but I can see that it has been well cared for.

Going by the state of mine at 70k miles, I reckon it would have been fairly obvious if it was original fluid. Did it stink? Mine did.

 

[FCS]

That is good news. I was just wondering what the main dealers would have done, new box for a start and heaven knows what else, no doubt a number of £ with lots of naughts on the end

 

[gt40]

That is good news. I was just wondering what the main dealers would have done, new box for a start and heaven knows what else, no doubt a number of £ with lots of naughts on the end

New engine as well because the low compression and misfire is what caused the gearbox to lose oil and go into vibration mode to compensate.