Coolant leak from W164 ML 420CDI - help

[Mark A]

I have had a coolant leak from my 2008, W164 ML-420 CDI for the past few weeks.

Leak isn't too bad, about 1 L in 3 weeks. As I was getting the brake problem sorted I asked my local garage to check it out for me.

It looks like a leak from the between the engine and bell-housing.

Is there anything in this area that can go on these engines.

They are now talking about dropping the gearbox out, which they estimate to be in the 8-12 hour range.

Many thanks in advance.

Mark

 

[kid-jensen]

With a big bill like that in prospect, I'd be tempted to put some K-Seal in and call it done...

 

[Mark A]

Is there anything in the bell housing area that could leak coolant.

Want to get the issue fixed, but don't want to get stung for work that didn't need done.

 

[Mark A]

Any of the indies know of a potential source for the leak in the bell housing area??

 

[Steve@Avantgarde]

The leak will be from something within the V of the engine, possibly the cooler or the extension between the inlet manifolds. The valley has various drain holes drilled into the block to allow any leaking liquid to disperse and there is a hole around the back of the starter motor which will run into the bell housing.

I would suggest you need to strip the valley of the engine out, you will likely have to remove the engine to do so.

I will have a look on WIS and see what the repair instructions say. Having just done turbos on a GL I know what a nightmare these V8s are.

 

[Mark A]

Many thanks.

Sounds like an even bigger job - engine out.

 

[Mark A]

Finally got a call back from the garage about the coolant leak. They haven't got to the leak yet, and started stripping things off to get down into the V and called a halt when they saw the state of the manifold.

Is this level of build up quite common.

I have had the car since 20K, it has about 80K on it now and is only used for commuting to and from work (84 mile round trip), so not lots of short journeys. I also put fuel system cleaner through once a month.

The garage is hinting at a new manifold, but I would have thought it could be cleaned up. Any tips on how best to clean it up would be appreciated. I'm going to go and see the garage this evening to discuss what next.

The strange thing is apart from the slight leak of coolant it was driving well and still had loads of get up and go.

Cheers,
Mark

 

[Steve@Avantgarde]

Hard to say without seeing it in the flesh. Or with a much better photo.

 

[kid-jensen]

You could always sell some of that coal to offset the repair costs...

Were there any other clues that it was getting so coked-up?

That sure is a LOT of carbon. I'm assuming it's coming from Crankcase gasses.....Might be worth looking into some form of catch-can for the Crankcase breather to stop this happening in future.

 

[Mark A]

I'll get a better look this evening. Photo was taken by the garage, so I can't really improve on the quality of it.

When I had issues with the old ML (270), the manifold was full of a more oily / sticky gunge rather than this stuff.

 

[Mark A]

Been to see it, it should clean up OK, it is more of a gummy substance than I was expecting from the photo's. I have given them the OK to get it out and clean it up. The biggest concern is what caused it. i guess we'll see when they get into it.

The bizarre thing is that if it wasn't for the coolant leak I wouldn't have known.

Will keep you posted.

 

[Mark A]

Manifold cleaned up well, gave the EGR's a good clean whilst in there. The leak was from the EGR cooler seals.

Picking it up tonight, fingers crossed that's it fixed now.

 

[doro708]

Hi Mark,

I know this is an old topic and i hope you will still see my question.
The leak that you had it was visible or the coolant was just disappearing ?
Also did you replaced the whole egr cooler or only the seals ?

Thank you ,
Adrian

 

[Mark A]

The leak was very difficult to see, we saw some drips from the bell housing area after leaving it on a large sheet of cardboard observing for wet patches.

We only had to replace the egr cooler seals fortunately.

Even after all of the work the garage did the coolant level continued to drop (but slower than before). In the end the garage put some k-seal in the system and it has behaved itself since then. Last time I topped up the coolant was a few months ago.

 

[doro708]

Thank you for the quick reply Mark.
I might give it a try until i get a new egr cooler even tough i can't see anything from there.

 

[202ChristianAmg]

Hi Mark,

I know this is an old topic and i hope you will still see my question.
The leak that you had it was visible or the coolant was just disappearing ?
Also did you replaced the whole egr cooler or only the seals ?

Thank you ,
Adrian

Hello. Ai was woundering if you have fixt yours leak. My one are leaking. Some told me too take a presour test on the Egr cooler. That it could be a inside leaking. And the water will go i the Exhaust.

 

[Mark A]

No further leaks recorded. Not sure about an internal failure of EGR, mine was definitely leaking from the seals rather than the matrix.

 

[Warren.]

Thanks for this topic. I have a 2008 ML420 and mine is leaking also. Now I know what to look for. I believe those O2 cleaning machines can clear carbon up but not that lot lol

 

[Warren.]

Roughly where is the EGR cooler located on this engine? Apparently you can check the EGR valve for signs of leaking?!

 

[Mark A]

It is under the inlet manifold. Quite a big job to get to.