Knocking plus Leak

[Dave ml270cdi]

Hi to all, I recently bought a ml270 auto, when the gearbox warms up I get a knocking noise when sat at around 1500 rpm, it will then go if i give some more power, when in neutral or park it is quiet as a mouse, also it is leaking fluid somewhere near the front of the box, but is not from the plug on the side, it only seems to leak when giving it some beans, especially towing, also twice now i have had break bind on the drivers side, leave it for 10 minutes and it is fine, could anyone please help?

 

[dokalj]

Hi Dave,

Welcome to the forum.

What mileage has your ML covered and what year is the ML?

It is recommended that the gearbox oil is replaced every 40K.

Have you inspected the box for leaks? If there is no visible damage, the seal could have perished or may not have been seated correctly.

With regards to the brake bind, is it the front or rear wheel on the offside? It could be the piston seizing.

Ideally you should take your car to an independent that is recommended on here.

Where about are you in the country?

 

[Dave ml270cdi]

It is the front offside brake, i have inspected the gear box, been in a couple of garages too, but noone has any idea where the leak is coming from, I am in somerset, thanks for the reply, it has covered 132k had new gearbox filter and oil

 

[dokalj]

Are you sure it is the gearbox leaking? Is there cherry coloured oil dripping? Have you or the garage checked the oil level in the gearbox?

It maybe something else leaking, such as a inlet manifold or diff seal.

Check the colour and which merc independent have you been to?

You could take the caliper off and see if the pistons work correctly.

Firstly, did you jack the car up and spin the wheel?

 

[Dave ml270cdi]

did not need to jack it up as the wheel was even too hot too touch, and the pads were smoking. it's either the gearbox or torque converter leaking, but somewhere around the bell housing area, also when we plugged in the diagnostic it was saying unable to select gear, another problem just found is n/s/f ball joints upper and lower, only 1000 miles from its apparent MOT, and a flat spot on the tyre with the canvas showing, bunch of crooks, I took it to my father in law who has 30 years experience with all motors but a citroen specialist

 

[Terry_]

Avant-garde automotive are in Somerset I believe. A good guy is Steve!
Why not give him a call??

 

[Dave ml270cdi]

I changed the nearside upper balljoint recently, so i removed the inner cover, low an behold i found the leak, was actually the inlet manifold, this is now replaced will now try and find the knocking noise

 

[panason1c]

The knocking noise could be worn engine mountings allowing the engine to flex under power and contacting the chassis or mounting bracket.

 

[Dave ml270cdi]

Its a constant knocking if holding rpm between 1600 and 1900 when going along and after it has fully warmed up, fine when cold

 

[Vlad]

Observation.....wheel too hot to handle.....would indicate a sticking capliper which would also explain the knocking noise you are getting

 

[panason1c]

Observation.....wheel too hot to handle.....would indicate a sticking capliper which would also explain the knocking noise you are getting

How would a sticking caliper cause a knocking noise? (just curious)

 

[Dave ml270cdi]

Brakes are sorted, took the caliper apart cleaned and greased, a lot more responsive since new inlet manifold and more torque, the knocking is not quite so loud now as it was, for some reason i am thinking maybe the torque converter maybe making the noise as it is only when moving regardless of speed it is in that rpm range, when in neutral or park it is quiet as a mouse

 

[dokalj]

Did your ML go into limp mode for you to warrant a replacement of the manifold?

 

[Danny DeVito]

Do u consider Thump thump as ur knocking noise like a kid hitting a rubber mallet on street light or tick tick like a clock ?

 

[Dave ml270cdi]

No it did not go into limp mode, it just had oil coming out where each of the flaps are, removed the flaps was going to put bolts in, but the plastic was so brittle it split.
Danny it is between the two descriptions you are giving, but only when fully warmed up and not under much load from 1600 rpm upto 2100 rpm, if in reverse it sounds to be worse, on closer inspection it looks as tho someone has changed the torque converter recently due to some tippex writing that is on it, if it was piston slap would it be knocking continuously?

 

[LozML270]

Did your ML go into limp mode for you to warrant a replacement of the manifold?

Mine is leaking oil dripping down the front it got progressively worse in first ten days of ownership but no limp mode and power seems fine. Where else could a leak come from? It's black not even a hint of red (a good thing?) will pop into local garage today but would love your take on this before I risk getting fleeced!

 

[Dave ml270cdi]

If you take the left hand wheel off, you can then take the plastic insert from the wheel arch, from there you will be able to see very clearly if it is the manifold, it is apparently quite common

 

[Dave ml270cdi]

Another problem has now arose, after being parked up for four weeks engine fired up reasonably quick considering the temperatures, but it is now stuck in park, must check switch if not not sure what next, maybe a newer ml