Vladds

So I went to the shop I usually go to and had them do an oil change and they passed the car through state inspection.
I am of the opinion of giving them some work, if I want to take the state inspection.
So I was there as things were happening, nothing crazy happened and I supplied filter and new washers for both drain plugs.
I guess I'm to comfortable with these guys and didn't watch as they tightened the plugs back.

Now I have a bad leak at the drain plug of the oil cooler.
Obviously 3 possibilities:
1. Not tight enough
2. Seat of cooler plug cracked.
3. mercedesgenuineparts gave me the wrong washer for the cooler, although I gave them the correct part number. Those two came loose in a zip lock bag.

So anyway, I saw even last time that more experienced mechanics are intimidated by the drain plug of the cooler and tend to under tighten as everything around there seems to be aluminum.
In case anyone else has this problem, tell the mechanic to torque the bolts.
SO:
Cooler drain bolt is 15 Nm
Oil pan bolt is 30 Nm

As I type this, I'm thinking... to small is the factory torque for my bolt to be under tightened at the cooler, I'm thinking cracked cooler...

I'm off to check with the torque wrench..

roadkillrob

Fingers crossed it isn't cracked, but at least they removed the oil properly - I was the first person to remove mine and the car was 3 years old and dealer services, bolt had never been touched, paint was still perfect on it and the washer was still painted over - half the paint fell off the first time I removed it so pretty obvious the dealer had never touched it.

deadlyvt

I have on more than one occasion been given the incorrect crush washer for the drain plug so don’t rule that out

Mort

When I changed my oil this spring I noticed the oil cooler plug had cooler insert threads attached to it. It was almost but not completely stripped out. I think it is likely I have over tightened it in the past. Anyway, that seems like a possibility in your case as well. I didn't want to be bothered with a major repair so I cleaned out the loose thread material and epoxied the plug back in. It had just enough thread left to hold the plug in place but not enough to tighten it up. It would have stripped it out completely.

Now I have to figure out a repair over the winter. If anyone has any suggestions for an insert or something else I would appreciate it. I am worried about getting filings in the oil cooler itself and perhaps causing further damage.

GL with yours Vladds.

I believe I was given the wrong washer as well. It was a copper washer and would work if you could torque it down enough but I am sure the original and subsequent washers I used were aluminum.

Vladds

whew...
Was undertightened.
The proper torque made the screw turn 3 quarters of a turn.
I ran the car on the jacks for 10 minutes, I don't see oil coming out anymore.

Next time I'll have the torque value with me and ask him to torque it.

On to checking oil level and cleaning the driveway now...

Vladds

My washer is Aluminum for the oil cooler and copper for the drain plug. The washer for the cooler is quite thicker than the copper one for the drain plug.

Did you price a replacement cooler?
Don't go for a used one, there is never enough of a guarantee that the used one you buy did not experience bearing material debris from a busted engine.
The metal flakes can never be cleaned out of there and wait patiently inside the cooler to be connected to the oil stream of a new engine, so that they can jump out of the cooler and into...

Bonesxxx

Larger plug and re-tap the hole?

roadkillrob

THat is what you most likely will need to do, use a lot of grease on the tap and drill as it will collect the shavings for you. I would recommend using timesert - they are much better than like a heli coil or other cheap type thread repair. You could just pull it off the car and rinse it good when done if you are worried about the shavings.

http://www.timesert.com/

Mort

This is my current thinking.

Thanks for the link and this was my second choice but I will research it further. It would be nice to have some stronger threads in there.

Good to hear yours was the easy fix.
A new cooler is a possibility, if the more practical repairs fail. I imagine a new cooler will be a few $$$ but I will check it out before I do anything else just to be sure.
I am not sure I will be able to get the bolt out again. I will definitely check out my options before I try.
Not changing the oil in the cooler might also be an option for the relatively small amount of oil that drains out of it.

Thanks guys.

curt.r

Ignore. Found it.

Yuille36

That is because the dealership don't drain the oil out of the cooler or the pan, they use a suction device that they attach to the oil dipstick tube to suction the oil out of the pan.

roadtalontsi

Most techs dealership or not, dont even know about the drain plug on the cooler. All AMG vehicle as per Mercedes Benz training should be drained out of the drain plug not vacuumed out.

Vladds

I checked the procedure for oil change in the WIS, calls for draining the oil cooler.

roadkillrob

The vacuum method certainly won't remove any of the oil cooler oil.

BalanBro

Nice thing about vacuuming it out at home is that you can change it frequently by yourself. I don't mind if there's a little old oil left, as I still got a bit about 8 liters out last time I used the Mityvac.

deadlyvt

It’s a simple job to open the 2 drain plugs definitely no reason you couldn’t do it at home

Homer Oz

G'Day Fella's,

Thank You Vladds and others for that info.

Regards
Homer

Jasonoff

Use the mityvac first then pop the plugs (cooler/pan) after to get the rest.

bentz69

Ive noticed when using the mityvac if you lift the front the car with jack then the oil cooler will drain back to the pan and you'll get roughly 1 more quart of oil as opposed to leaving the car level

Jasonoff

Interesting, I'll give that a try next time.

skratch77

My driveway is on an incline so I just let gravity do its thing.

Vladds

I'm not sure of this but a n engineered oil cooling solution would have an oil thermostat for the cooler
So the drain-back would happen with hot oil but may not happen with cold oil.

Homer Oz

G'Day Fella's,

bentz69, my Dumb question for the day - Are you undoing the Oil Cooler drain plug as well, or only the Oil Pan drain plug, when you do this?

Regards
Homer

bentz69

Neither because I use the mityvac. If your not using the mityvac just remove the plug from the pan.

Try for yourself. If using the mityvac or draining directly from the pan then drain the oil when the car is level and wait for it to stop. Then Jack the car up and wait for the remaining oil to drain back from the cooler into the pan and out the hole or start pumping the mityvac again. You'll get an extra quart.

Just remember that since you now drained the oil cooler you'll have to add that additional quart back

Homer Oz

G'Day Fella's,

Thank You for that additional info bentz69.
Not being previously familiar with them, is this the Mityvac unit you blokes use?
https://mityvac.com.au/product/mityv...uid-evacuator/

Regards
Homer