Is this a MB trans dipstick?
 

Whilst looking around the engine the other day, I came across what looks like a dipstick for the MB transmission in my XKR. It's located at the rear of the engine compartment, on the right hand side and just behind the plastic air inlet trunking to the throttle body. There is a steel tube, about 10mm in diameter that drops down towards the bell housing and then back out of sight. On top of the pipe is a black plastic cap, roughly circular but with a flat on one side. On top of the cap I have been able to make out the words 'MB Workshop Use Only'. It rotates freely so I don't believe there is a dipstick in place, and I can't get the cap off.

Anyone got any thoughts?

Thanks,
Andy.

There is no dipstick in there, and the cap is sort off sealed, it will brake of a plastic piece if you force it of iirc. So it sounds like the oil hasn't been changed, good time to do it now.

You need to break the red seal to remove the cap. You will need to purchase a Mercedes dipstick tool to check the level. They are available on ebay.

When you are done with the transmission work, you can buy a new seal at a Mercedes dealar for less than a dollar to put it back to the factory state, or just reuse the old broken seal and remove it next time with a pair of pliers.

Thanks guys. So am I right in thinking that it is an empty dipstick tube with a sealed 'customer proof' cap on top?

Avos, I'm sure you are right, but how can you tell the oil hasn't been changed? I am keen to change the oil but I haven't been able to find a concise step by step guide to doing this, but I've seen reference to draining the torque converter and removing the gearbox sump etc.

WXKR, am I right in saying the dipstick is pt. no. 140589152100 and is it not possible to leave the dipstick in the tube after doing the work? Also, I can't see any red seal on top of the cap, but I can see where something might have been fitted previously, it's hard to tell. how is the cap supposed to be removed?

Thanks - Andy.

A dipstick is available for the ZF 5HP24 transmission on the xk8 & xj8

Link 5HP24 Dip Stick

140589152100 isn't the right one, you need something like this:
Mercedes Benz C230/C280/C43/C240/C320 722.6 Transmission Fluid Dipstick Tool | eBay

Its just a guess if it hasn't be changed before based on the comments that the cap is fixed. I still have the original cap and have replaced the oil already several times, never bothered to get a new one, and would take it most wouldn't.

Yep, and I'm hoping to take this off and put in my eBay dipstick today. Silly that it didn't come with one, but amusing about the markings on the cap.

There may be a broken tab in the cap. See if there is a bit of a red tab visible from blow the cap. Use your finger or a tiny screwdriver if necessary to slide it up, then pull it from the top. Once the tab is out the cap should easily come off.

My cap actually came right off- the tab apparently has been broken before.

Does the dipstick not fully insert? I only got it halfway in, was able to take a reading, but it doesn't appear it's designed to stay there. Is this just a tool?

The MB dipstick isn't intended to stay in there, and doesn't go fully in (it should stop at the sticker ring above the 80 degree mark)