Confession: I'm an idiot

[rich1068]

When I picked up my W209 CLK240 last week the previous owner warned me of a slight transmission fluid leak. Fair enough I said, it's mentioned on the MOTs, no problem. How do you check the level? He directed me to a covered tube towards the back of the engine and said it's there but there's no dipstick. He just put a drop in every now and again. While looking round the engine bay I also asked about checking the engine oil and was told that Mercedes didn't fit an oil dipstick either and a reading was available via the dash display. OK, no problem.

Can anyone see where this is going?

So fast forward a few days and my eBay transmission dipstick arrives, I check the level and not only is it completely wrong (too high) but also entirely the wrong colour and smell. Not good. Off I go to consult with a gearbox place I've used before. They agree, wrong stuff. Possibly manual transmission fluid? Previous owner had the fluid and filters changed back in 2011/20k miles ago but we agree it might be a good idea to do the job again and maybe avoid driving it until they can get it in.

And that's where we've been until about half an hour ago. The car's been parked up at work, a few little jobs done, engine oil and filter, bits of trim, me being pee'd off I can't run it. So today my wife's working and I'm at home with the kids because it's half term. I'm idly browsing some YouTube videos and I watch this Russian guy checking the transmission fluid. "Hang on a sec. That's not the same tube I've been putting the transmission dipstick down..."



Tomorrow when I get to work I will check the fluid using the correct tube. And then hopefully I will be driving the car. Possibly to the gearbox place to tell them it's not so urgent now

Does beg the question how often the previous owner put transmission oil down the engine oil tube. Bless.

 

[m80]

Putting a bit in now and again could mean it's over flowing.
For me being sure any leak is resolved would be 1st,
then an ATF service to include filter and 'o' rings. It could be leaking past the plug 'O' rings as that isn't uncommon, but should be fairly obvious on inspection.

You would expect a specialist to use the right hole. While I've heard some get that wrong I thought that was just on the porn sites.

As there seems to be some doubt as to service style replacing engine oil and filter would be a must for me.

 

[rich1068]

I think he's been putting a little bit in now and again but down the oil tube not the transmission tube. There could well be a weep on the transmission but at least I now know how to keep an eye on it properly! Certainly a transmission service is a good idea but tomorrow should tell me whether it's now or at some point.

Regarding the specialist, it was me who showed him what was on the dipstick with my tool when I called. No doubt he'd have pointed out my mistake if he'd had a closer look.

As I said above, I did do the engine oil and filter the other day so any possible transmission oil in there is now gone.

 

[markjay]

Quite a few people get confused between the transmission dipstick tube on the 5g and the engine oil dipstick tube, which is why MB put a cap with a red locking tab on the transmission dipstick tube (to prevent people from pouring engine oil into the transmission, or from sucking the ATF using a vacuum pump, thinking they are removing the engine oil).

That's possibly one of the reasons that MB removed the dipstick tube completely from the g7 and g9 transmissions.

Regarding the oil leak, the 5g box typically leaks from the pilot bush, which is the large electrical connector under the transmission.

 

[rich1068]

I just took the previous owner at his word and assumed there was no oil dipstick tube at all. Does seem odd that Mercedes would go to the bother of fitting one but then just putting a cap on it. Looking forward to tomorrow morning when I can check things properly!

Regarding the oil leak, the 5g box typically leaks from the pilot bush, which is the large electrical connector under the transmission.

That's what the gearbox guy said too. I cleaned the undertrays the other day when I did the engine oil. Also cleaned up all round the engine and transmission sump so might drop the trays again shortly and see what's what.

 

[markjay]

That's what the gearbox guy said too. I cleaned the undertrays the other day when I did the engine oil. Also cleaned up all round the engine and transmission sump so might drop the trays again shortly and see what's what.

On order to replace the pilot bush, they'll need to drain the ATF from the transmission sump.

At this point you have three options:

- Get them to carefully collect the ATF and then reuse it.

- Ask them to use new ATF when refilling, which means you'll have to pay for the new ATF and that you'll have changed about just over half the ATF and 'refreshed' it a bit.

- Ask them to replace the ATF with new and also drain the torque converter and the heat exchanger, and also drop the sump and replace the ATF filter, this will cost more but you'll have a complete transmission service.

 

[W1ghty]

The electrical connection can be changed with very little loss of ATF fluid . I did it last year on my 5g CLK.
But as Markjay says , it might as well be done with a gearbox service

 

[Teego]

Just change the ATF and filters plus engine oil and filter. Not expensive via an indie.
Lube is Life.

 

[rich1068]

Changing the ATF and filters is certainly on my list but now not as urgent as I originally thought. Arrived at work this morning where my car has been since last week (pre yesterdays revelation) and correctly identified the transmission dipstick tube. Level is correct for a cold transmission and the fluid is OK in colour and smell. I'll warm it up today and check again later.

 

[W1ghty]

Changing the ATF and filters is certainly on my list but now not as urgent as I originally thought. Arrived at work this morning where my car has been since last week (pre yesterdays revelation) and correctly identified the transmission dipstick tube. Level is correct for a cold transmission and the fluid is OK in colour and smell. I'll warm it up today and check again later.

Was the Level checked , engine running , flat ground , gearbox in P ?

 

[rich1068]

Yes.

 

[Petrol Pete]

At a push you can change the (cheap) TCU plug without draining the box . Jack the left side of the car up as high as you feel comfortable with , remove the TCU catch the fluid that comes out in a very clean container and pour it back in when finished.

But a full transmission service is reccommended. Just adding a bit 'now and then' is not a great idea . Plus , buy a transmission dipstick.

PS . Lets hope the previous owner has not been getting the wrong fluid in the wrong hole ( ) they don't play well together, particularly engine oil in the transmission can destroy the clutch plates.

 

[rich1068]

Don't worry, when I get it done it'll be done properly. And as above, transmission dipstick was one of the first things I bought. And since this morning I can report that with everything up to temperature the level is bang on

If anything the previous owner has been putting the odd drop of transmission fluid down the oil dipstick tube but not so much of a problem as I've now changed that.