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Hello fellow benz owners,

I had recently purchased a 2015 Mercedes CLA 250, and had driven it about 500-600 km as then I had received the notification of change oil on the dash.

Reading throughout these forums and watching a lot of videos of the oil change I had thought i known what to do. I had done the following

1. Take off splash guard
2. Take off engine oil and dipstick
3. Used a 13mm to unplug the drain plug
4. I let the oil drain into a pan (i disposed of this oil at a canadian tire)
5. I unscrewed the oil filter and removed the 3 gaskets and old filter and lubricated heavily the 3 gaskets and put them in their corresponding spots & put the new filter in
6. I screwed on the oil filter
7. Put drain plug back with the washer that was there
8. Put new oil in the car castrol 5-30w
9. I started up the car and went to see for leaks.....

At step 9 is where the issue came.. (please see photos) the oil is leaking HEAVILY , not drips, but HEAVY HEAVY leaks once the car starts and only stops when I turn off the car. It is leaking BEHIND where I unscrewed the drain plug like behind the drain pan.. I didn't unscrew ANYTHING behind there or anything close to it. I even checked my drain plug if that was the problem of the leak and it is NOT. NO oil comes from the drain plug when I tighten it but it comes from behind the drain pan area like behind the silver box holding all the oil...

Could anyone please throw any help my way..? This was my first and only car I have and its been out of service for 2 weeks.. I was ashamed to ask for help as everyone said changing oil is such an easy thing but I have no other option to resort to here... please leave any comments or feedback on how to fix this :/ IMG-2482.JPG IMG-2480.JPG
 

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5-30 may not be ideal for the turbo ... but anyway

- what torque on drain plug?
- which direction was filter put back?
- was dipstick out when pouring oil back?
- how quickly was oil poured back?
- what torque on oil filter cover?
 

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Discussion Starter #3
5-30 may not be ideal for the turbo ... but anyway

- what torque on drain plug?
- which direction was filter put back?
- was dipstick out when pouring oil back?
- how quickly was oil poured back?
- what torque on oil filter cover?

1. Did not torque drain plug (when the leak occurred it was not leaking from there)
2. The filter piece itself like the fabric thing only went on a certain direction so I know that was correct, and I first put it onto the piece that holds it and twisted it to the right (to tighten it)
3. Dipstick was put back in before putting oil
4. I put the oil in as fast as I can, used a funnel
5. Did not torque that either, but I made sure it was really really really really tight like I tightened it the maximum I could

Ps. Thanks for your help ❤
 

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Oh boy
3 and 4 may have caused oil to go where it should not ... dipstick needs to be out (as a vent) and oil goes in slowly (to avoid flow back)
If you over torqued the filter housing it may have cracked ... its only polymer
 

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Discussion Starter #6
Oh boy
3 and 4 may have caused oil to go where it should not ... dipstick needs to be out (as a vent) and oil goes in slowly (to avoid flow back)
If you over torqued the filter housing it may have cracked ... its only polymer
Should I remove the oil filter and see if it cracked or anything? Im not a mechanic or anything but would you know how to check for cracks/where?

the oil was going in decently though, like I would let the funnel fill up and stop for a bit until empty and re-do... but I do honestly think it has to be the oil filter not being torqued or being tightened to a point of no return...
 

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Discussion Starter #7
...and you also may have added too much oil.
That would be the last thing boss.. the car takes 5.9 I added about only 5 and dipstick seemed okay so to see for leaks (not waste any oil) I started the car with about 5.5 L.. and the leak caused chaos.. its leaking from behind the drain pan.

Is there perhaps a drain plug located elsewhere that may have come loose? or is there only 1 drain plug in the front ?
 

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Engine oil must be added slowly for M270 engines as stipulated in Mercedes WIS. Attached useful torque valves of bolts during engine oil change.

SI00.20-P0007B.png

Torque Engine Oil Change.png
 

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@werks400
Yup! Just wish there would be little “?” markers to click and pop up more useful details like “pour oil in slowly to avoid cavitation and transferring oil into intake channels” or “dont over torque lest the thermoplastic housing gets damaged”
I mean geewhiz ...
 

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That would be the last thing boss.. the car takes 5.9 I added about only 5 and dipstick seemed okay so to see for leaks (not waste any oil) I started the car with about 5.5 L.. and the leak caused chaos.. its leaking from behind the drain pan.

Is there perhaps a drain plug located elsewhere that may have come loose? or is there only 1 drain plug in the front ?
Glad you're so punctilious, and thanks for illustrating my point:
If the car takes 5.9, won't most people just add 6?
 

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@werks400
Yup! Just wish there would be little “?” markers to click and pop up more useful details like “pour oil in slowly to avoid cavitation and transferring oil into intake channels” or “dont over torque lest the thermoplastic housing gets damaged”
I mean geewhiz ...
Mercedes would say: Yes yes.. We could do this.. These are "Options" and would cost $xxx :badgrin:

Anyway, I bet no one would keep their engines idling to operating temperatures after an oil change; and then wait that extra 5 min just to check the oil level. :sign_tbnt:

How to check Engine Oil Level.png
 

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Well I suppose they want to take into account thermal expansion and running conditions like surface tension and pump channel volumes but unless the measurement conditions are the same each time the static cold check at cold conditions will be the most consistent way to determine sump volume ... which apparently for these motors a high volume is more detrimental than a lower one but of course at least some predetermined minimal running volume to avoid starving the pump
 

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Hmmm looks like someone did an oil change with a half-hearted research.
OTOH ... it is supposed to be "just an oil change" so it should be just that ... but of course all sorts of little tricks are not public so good thing we have this forum and nuts like us to broadcast them ... :cool:
 

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This is pretty bizarre. Hard to troubleshoot without being there.
Trying to think what could possibly cause this?

Possibly: mis threaded the filer housing cap, and it is jammed., but not correctly in place. It could then leak from the filter housing and drip down towhere it apparently is coming from.
Also: Overthigtened the filter cap and cracked it. The torque is pretty low, something like 25NM afaik. If it is cracked it should be obvious by visual inspection.
If that is what happened, the remedey would be getting a new filter cap, should not be too expensive. Should be able to see if there is any oil coming out of the filter housing, either through a crack or
through the threads.

I would start by removing the filter housing cap, double check if the filter was put on the plastic spike in the correct orientation. It can go on 2 different ways, I forget which way the rubber 'skirt" needs to face.
I think it should point towards you, away from the cap. There are some pictures somewhere on this forum, pls check. Re-Check if all 3 seals sit in their intended grooves.

Visual inspection should reveal any evidence of mis-threading ( damage to the threads) ,
or cracking, it is hard plastic so it should be easily visible. When you put it back on, carefully hand-thread it first, make sure it turns easily for several turns
before attacking it with a torque wrench. As I recall, it turns quite a few times before it starts getting tight.

Just to be sure, check the drain plug also. usually the plug's metal washer is replaced if the drain plug is removed. I had some minor leaks on some cars when reusing the old washer. The washer
is soft metal and it "forms" to the plug to make a perfect seal. In any case, if it was leaking from the drain plug you would easily see it, and it would be a slow leak.

If you figure out what the cause of the leak is, then there is the cleanup issue. If indeed leaked from the top side ( e.g.: filter housing)
You may have a fair amount of oil covering parts of your engine now. Best case, it just smokes for a bit and evaporates.
Worst case heats up and catches on fire. You may need to have it steam cleaned, or use a degreaser and wash it off.
If you decide to degrease your engine yourself, be careful not to get water into the spark plug wells.
easy to do with a pressure washer...(do not ask...)

If for some strange reason you have grossly overfilled the oil, you could have caused some seal damage. This is probably a dealer/mechanic fix, and not cheap.

One possibility ( unlikely so please forgive me for putting this on the table) is draining the tx fluid instead of the oil and then grossly overfilling the oil.
The tx fluid looks and smells different than the oil and the plug looks also different as far as i remember. so that is why its unlikely.
You can check the dipstick to see where the oil level is, and if it looks clean now. If it is clean and at some reasonable level, you probably drained
correctly.

Next: never had this problem as I tend to fill the oil very slowly, but some folks say it is possible to fill he oil too fast or without removing the dipstick.
The oil then can enter some undesirable part of the engine and subsequently drain back out. jms or Piccard may be able to better help troubleshooting
if this is what happened, and propose a remedy. If you just had a fill problem, the oil will eventually drain out from where it should not be and then
the draining will stop and the dipstick level will not decrease.

If you truly never changed the oil on any vehicle, there may be something that the rest of us are just instinctively doing correctly, and not think of
a possibility of done differently. You may need to get a mechanic or more experienced DIY friend help out looking at this.
Have someone look at this may not be the worst option, do not feel bad or embarrassed. By all means re-check the obvious
possible errors that are easily checkable first, In my DIY history, I have done worse. E.g.: Snapping off bolt heads
happened to me quite a few times, when I tightened them instead of loosen. All to easy to get turned around when a bolt is facing
away from you. :) . I also broke several brake bleeding nipples. It is a learning process, and accidents happen.

Be prepared, your desperation factor may jack up the price tag.
 

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Yeah the busted oil filter cap is high on my suspect list when torquedthehelloutofit was mentioned...
Your gearboxfluiddrainedinstead comment scared the heck outta me! My first ever full drain is due next so good grief that will be triplechecked!
Though the dipstick was mentioned ... though cant recall if it was checked after fill?
 

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Re reading the OP: I think there is a clue here: no leak unless the oil pump is running.
That makes the filter cap the most likely culprit. I think the poster would have noticed if the cap cracked.
It would make a noise, upon breaking.

But if it was mis-threaded, it would become really hard to turn pretty soon.
but it would not fully seal. That is what my money is on.
 

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The tx drain plug is totally different from the drain plug, The OP mentions using a 13mm socket, that is about right for the
drain plug. So we can rule out draining the tranny instead of the oil.

The entire filter housing is bolted to the motor block with a single large bolt, and uses a gasket there.
wonder if this connection can get loose given enough force when tightening the filter cap.
It has to be leaking either from the top of the housing, or the bottom. here is the pic of the filter housing, its gasket and how it attaches:

https://www.oemercedesbenzparts.com/oem-parts/mercedes-benz-oil-filter-housing-gasket-2701840280?c=bT0xJmw9MiZuPVJlY29tbWVuZGVkIFByb2R1Y3RzJms9MQ==
 
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