RawBenz

Keep in mind this is a Right Hand Drive vehicle.

I'd noticed this afternoon after i'd done a fair bit of driving today, that there was a substantial amount of Motor Oil on the garage floor.

It is coming from the passenger side (RHD Car) near the control arm (hard to see because of all the undercarriage plastics etc)

The leak is closer to the firewall on the opposite side of the oil dipstick.

There was no oil in the morning.
I drove home, washed the car while it was running (the car was on the whole time i was polishing it) then i drove it into the garage.

About an hour later i decided to move it out and that's when i noticed the oil.

I inspected the engine, inside and around the engine components etc and no oil from the top.

What could it be?
I thought i'd get peoples views first before i have it sent to the workshop on Monday.

I've downloaded a pic off google which shows the complete engine from a high view, i have also made a red box to give people an idea of where the oil is located under the car. It must be coming from somewhere within that Red Box location because the Oil was grouped on its own towards the front passenger wheel. (RHD Car so the passenger wheel is right next to that red box.

RawBenz

***Note this is not my car as i've just used this from google as a diagram to show where the oil is coming from***

Gadget

Oil leaks can be like water leaks and end up far from the true source.

Easiest way to find it is to clean everything the best you can and then put an additive into the engine oil that will glow when a black light is applied. That way you can trace the oil back to its source and identify it.

It could be as simple as some spilled oil from your last oil change. The belly pans can hold a lot of oil that can be floated out when you wash the car.

G

jmueller

I wish I could help, but why the hell are you washing you car with the engine on? Was it a machine wash or a hand wash. A hand wash takes me at least 20 minutes to complete... Sorry, I'm just curious.

Case1906

RawBenz

Yeah took about 20min.

I'd been driving the car extremely hard for about an hour. So when I got home I thought id let it cool down for obvious reasons... And gave it a quick wash/polish.

jmueller

If you were driving the car that hard, where you felt it needed to cool for 20 minutes, you may have had the oil temps up near 260-280? Did you look at the temps before you parked it? If the oil temps were that high, and it was overfilled with oil, the oil may have expanded and then leaked as a result. Hard to diagnose over the internet really.

RawBenz

I think it would have been about 120-130deg Celsius, which is around the temp you quoted.

I'm starting to think it could be related to the control arm or bushings because that's where the oil had come from. The hole in the undercarriage plastics near the passenger control arm. Maybe a boot is cracked/leaking..

Also jmueller - That's a great stock time! 12.2 @ 116 STOCK is a very good time! Congrat's. There's a lot of people here who have spent thousands $$$ and they can only manage times that a stock 63 runs.

Ingenieur

Are the engine mounts fluid filled?
Clean it up
Put some paper under it
Run it and see if it leaks again

Has the oil level changed?

Btw it's better to cool the car down by a few minutes of easy highway driving before you park and shutdown... Move air over the radiators, etc.
Idling is not a good way to do it

RawBenz

That was the first time i did it, it was a coincidence.

I always let it cool down for 120seconds because of the blower.

But i'd been giving it a hard time then when i get home, i hosed it down, quick chamois then ran over it with a quick polishing rag and that's it.

It's more of an issue if you let it idle for too long on start up, burn the valves etc.
But, after it's been driven for a while, 20mins of idling is fine, i think (i'd never done it before and won't) but think about being stuck in a traffic jam for an hour etc.

I think the M156 would've been designed with that in mind. (being stuck in traffic for 20-30mins etc)

I checked the catch can and everything seems fine, the lines etc.

So i wouldn't have a clue where the oil came from. Looking under the car (without having it on a hoist) i can see some slight oil (not on the boot) but near the passenger control arm, in and around up there but i can't see much because of the cover.

I clearly suffer from OCD because even though it doesn't seem like a huge issue, i always want to know where it's coming from, why it happened etc. I want to always find the source of the issue.. I could spend hours pulling things apart and putting them back together just to find out why/where/when etc.

roadtalontsi

yes the engine mounts are fluid filled, do you fill any excess noise or vibration from the engine?

RawBenz

I've just checked with a white rag and the oil is red when it dries.

It's def not motor oil.

I have noticed vibration recently only when the car is cold. But that was after the new set of headers went in, I thought that could be the reason, but yes on startup and when it's cold until it gets to full operating temp it does vibrate a fair bit trough the cabin etc

RawBenz

So i've narrowed it down to two things.
Either a transmission leak (which is highly unlikely as i only had the tranny done and re-installed recently)

Or

Engine mount - Which i think it is. The colour of the oil on the day was a dark brown/red (liver) colour.

Also the splashes on the under tray are red. When the colour dries on a white rag it's red.

The other thing is because on cold starts there is a lot of vibration through the car. I thought this must have been after the new headers and piping went in a few weeks ago because that's when i really noticed it, from then onwards.

The car still drives perfect. No knocking from the engine, no looseness etc.
I've done engine mounts in other cars and it felt as though the engine was moving around loosely for obvious reasons.

I cleaned where the leak was visible today and after a long drive when i got home i noticed there was a tiny dot of oil there, so it is clearly leaking.

I've been told to replace both mounts instead of changing the one as it's better and the drivability will be much better and to also change the tranny mount too.

So has anyone else had any experience with C63 M156 Engine mount replacements?

RawBenz

So got some good news

It turns out it is the Engine Mounts. Will be replacing both engine mounts and transmission mount while we're there!

jmueller

Thanks! My car was really rocking and rollin' that night at the strip. Don't know why she is so quick, but my engine builder must have been having a great day at the office. Don't really know what else to say. Anyways, I am glad you found out what the problem was. Do you happen to have a picture of the fluid leak? It may help out people in the future who have a similar problem. Also, what was the cost of replacement, if you are not under warranty anymore that is?

RawBenz

I'm still under warranty but it's classified as wear and tear item. My warranty ends soon, with all the mods on my car i doubt they'd warranty anything besides interior stuff etc.

I wish i had taken a photo.
When you look at the oil it looks black. If you touch it with your fingers it's thick like engine oil but becomes red when it dries. Dark Brown/Liver colour.

whoover

That's a bit of a ripoff. I've had engine mounts replaced on many MB's under warranty. As soon as the idle gets a bit rough, I know it's time. I guess the Aussie warranty has different terms.

RawBenz

I know.
I can't complain because they do look after me a lot at Mercedes.
Plus i didn't want to get into it with them because i have done a lot of mods to the car that they are aware of and didn't want them to say it was because of that.

I would've bought the parts off the web and had my performance shop install them but Mercedes is offering me a good deal and giving me a free service etc.

So i'm changing engine mounts and tranny mount while we're there.

Honestly, the only symptoms i've seen besides noticing the oil leak, is vibration within the cabin (enough to make the passenger seat rattle on idle) - Vibration through the steering wheel at idle. This i thought was from the recent installation of my new headers/pipes etc. But clearly wasn't. But once the car warms up, there's no vibration.

And that's it.

Car drives the same etc.

I remember, i'd done engine mounts in another car and it felt like the engine was moving around on braking and acceleration lol. Felt like it was going to fall out or come straight through the firewall.

fraktv

It's a tight fit to get the headers in. I've also heard that the engine has to be lifted slightly to get access (meaning loosening up/removing engine mounts). Perhaps your header installer (unless you did it yourself and know for sure) put additional stress on the engine mounts or didn't remove them during header install. You may want to check with them and recoup your losses if he admits to not loosening up the mounts. Just a thought....

Ingenieur

I called it!!!!

RawBenz

Yeah i remember when he took the old headers out they were a perfect fit.

The new headers he had a slight issue with.

RawBenz

+1 hehehe.

I'm just glad it's not the transmission, cause we'd just had that put back in after working on it, software was re-done etc.
Then i was thinking 'oh no i hope it's not a tranny leak'

The funny thing is, after the day i found the oil, the was never anymore oil on the ground.
So that was kind of the giveaway that it's the mount because all the oil had probably come out.

Now there's tiny speckles within the plastics underneath but that's all.

BLKROKT

Glad it was just a motor mount! On a related note, in my former car circles (996TT and DSM), we used to replace our motor mounts with ones with a stiffer polyurethane insert pressed in (some maniacs would put in completely solid motor mounts like me haha). Has anyone attempted that on the C63's? I liked the feel - a bit more vibration transmitted into the cabin, but everything seemed... crisper without the motor and tranny moving around so much. Any thoughts of doing this while you have them out?

RawBenz

I was going to go for some 'performance' mounts but they just vibrate and make a lot of noise and it's unnecessary for C63's as the standard mounts can really sustain a lot of power and abuse.