Not very cool, cooler -

[spock500]

Here's a real puzzler, these things always seem to happen to me

I bought a w210 2/3 weeks ago which I have been using as a daily driver without a hitch, no leaks, nothing.... until today.

I went out to do an oil change but first checked I had the right oil filter so i unbolted the hex cap and pulled it out, yup all fine so ran it down to asda to warm up the engine -

pulled the bonnet to find oil leaking from the front offside wing, couldnt make out where it was coming from so took of the undertray which revealed the oil cooler dripping black oil -

I went ahead and did the oil change fired up the engine for a few minutes, even cycled through the gears in case it was th tranny oil cooler but nothing, no leak, no drips -

Totally puzzled, this is what it looked like before I cleeaned it up -

 

[Dieselman]

Tpo answer your question from another thread, that is the engine oil cooler, the transmission cooler is duplexed with the coolant radiator.

I suspect you let oil from the filter run down the cooler pipes and onto the cooler.

For a full oil change undo one of the cooler couplings and allow it to drain.

 

[spock500]

Cheers DM, I was going to undo the couplings but didnt want to complicate matters when looking for the leak. I just couldnt believe it had started leaking the moment I took the oil filter cap off, seemed more coincidental than anything else.

This is the AvantGarde spec, not sure what that is but the suspension is very firm almost bumpy, the front of the car rides low with the front skirt skimming on speed humps.

I just wondered if I had grazed it someohow on one of those.

 

[spock500]

Just took her out for 15min run and checked for leaks, nothing which is great but cant help think im missing something -

Will check the oil level in th morning but what I did notice looking at the front is just how low the oil cooler is, tried taking some pics but got the angle wrong -

 

[Dieselman]

You only catch the front apron and undershield when coming off humps, never the cooler.
New springs and dampers will help reduce the grounding.

 

[spock500]

I think your right on that as no scratches on it - will give it a proper clean once over tomorrow now i know where to look.

So cold again today, hands blue

 

[spock500]

After run, no visible scratches -

 

[Dieselman]

Judging by the dirt on the coupling it looks to have been leaking for a while. Maybe when you undid the filter it broke the vacuum in the pipes, but if that's the case why doesn't it leak when under pressure and flow.

Strange.

 

[spock500]

When I undid the filter lid it hissed for ages as the air squeezed in - it wasnt long afterwards I noticed the puddle (yes puddle) of oil dripping from the wing - i was confident it was engine oil as sooty black.

Can it be soldered?

 

[Dieselman]

Unlikely but it could be recored but a new oil cooler shouldn't cost too much.
It's just strange how it hasn't leaked under pressure unless the thermosotat isn't opening to allow any flow.

 

[spock500]

Maybe its on the 'pull' side of the oil pump and as you say being held in by vacuum -

Just went out to put a cardboard box underneath to catch any drips overnight, if there is none will wrap with cloth bandage and repair next time I do an oil change.

I have some 2 part glue which i might try on it if the leak is visible, its a commercial product not available retail - have used it to connect hose tails to heat exchanger but as yet untested.

 

[spock500]

Ok, I cleaned the fitting and it look as though there maybe a small leak where it is fitted to the oil cooler, this looks to be soldered on or brazed - it does certainly look repairable

I bandaged the pipe, fitting and bottom of the cooler in case it does spring a leak will check oil at regular intervals but on the next change will remove and repair, took photo of all bolt locations.

Notice how low it is, just above front spolier

 

[spock500]

Whilst fitting the under tray back wasnt sure whether the blue edge goes inside the pink edge, it does fit but looks awakward - the 'belly' of the undertray looks a bit floppy without a middle support of some kind.

Is that right?, the rubber lip inside the plastic front spoiler?7

 

[Dieselman]

Well, normally they aren't coloured so it's difficult to reference exactly but..the frontal rubber strip goes inside the bumper lip as you have it, then the rear of the front section bolts up tot eh subframe (with spacers if you want to avoid a rotten subframe), then the centre section bolts on.

It's loose because it's not bolted up.

 

[Dieselman]

Ok, I cleaned the fitting and it look as though there maybe a small leak where it is fitted to the oil cooler, this looks to be soldered on or brazed - it does certainly look repairable

The coupling block screws into the cooler body. That leak looks like the main pipe coupler may be leaking, it may just want tightening a bit.

 

[spock500]

There were 8 bolts with integral flat washers -

Two went into the front wing (nr oi cooler) four in total, two right at the front near the front edge of the air dam and two right at the back -

No more bolts and didnt see anymore holes?

 

[spock500]

The coupling block screws into the cooler body. That leak looks like the main pipe coupler may be leaking, it may just want tightening a bit.

Thats good news DM as its definitely coming from one of the joints - have this on the to do list when i next do an oil change which wont be long as I like to flush it a few times with new oil

Thanks for all your help (again )

 

[Dieselman]

Later front sections have three each side, but that's not an issue. As long as the front and centre undertray sections are bolted up, that's all you can do.

What's the ty-wrap for.?

 

[spock500]

I forgot, took a pic of the undertray

 

[Dieselman]

I can see now. The front section should bolt on first, then the centre section bolt through it to the subframe.