Hi everyone,

I just did oil change on my 99 SLK 230 yesterday and used a new filter kit from the dealer. After I was done, I started the engine and it all seemed ok. After running the engine for about a minute, I noticed oil leak from the O-ring. Turned the car off and dried the area. The O-ring had a bulge at the area where the oil appeared. I removed the cap and made sure all is in the right place. The O-ring seemed as good as new. Replaced and tightened the cap a little bit more that a hand-tight. Inspected the O-ring and made sure there are no bulges. Started the engine again. No leaks for about a minute, but as soon as started warming up it started tearing up (see pics).

It almost seems like it is building pressure and pushing the O-ring outward.

The only thing I can think of is that at the time I replaced the filter, the housing looked really dirty, so I used a long screwdriver and a rug to clean it up. I noticed two valves/sensor looking things at the bottom of the oil filter housing. I hope I did not damage any of them...

What are those two things and how can I test they are still functioning? Any idea why it is building pressure from the inside?

Thanks,

Rick[/align][/align]P.S. I used a brand new kit from the dealer - filter and O-ring. At the time of the install I made sure the new O-ring is seating right and tightened it about 1/4 turn with the wrench more than hand-tight. It looked nice and evenly pressed on all sides. After running the engine for about 1 to 2 minutes, I actually noticed an oil spot on the floor and more of a slow stream of oil coming down from a different bulge. Stopped the engine and cleaned the area with brake cleaner spray. Removed the cap, dried and inspected the O-ring, replaced the cap (1/8 turn with the wrench) and verified the O-ring is not bulging. This time I actually just stared at the area for about a minute and then I watched the O-ring deform and bulge before any oil came out. I shut off the engine right away before taking the pictures, that's why it shows just a little bit of oil. Cleaned the oil again and took another pic to show the bulge.

I will try to take more pictures from different angles and from inside the housing.

I do believe it may have something to do with the filter bypass and drain back AFAIK... I may have damage them with the screwdriver...

What effect will they have on pressure if both are fully closed/clogged up? Can they be replaced?[/align]

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are you installing the oring in the correct groove? not flush with the top of the housing but
in the groove just below it.

 

Good point made by Chassis221.

Are you sure that you are tightening the black cover correctly.
The o ring should not be visible when correctly tightened.
Looks like the O ring is still showing.
Note. As the o ring goes into its correct position (subject to being in the correct groove) the torque required to tighten goes up quite a lot and is usually greater than "finger" tight. So 1/4 turn is not enough to sat the cover correctly.
Correct torque is identified on this component (I think)

stuart

 

O-ring seals if two surfaces touch and the o-ring fills a 45* chamfer or inside the cylinder, that tighting tighter does not compress the o-ring any more. Tightening any more that when the two metal surfaces touchs only hampers it's sealing ability by disstortion.[[ O-ring must be in it's proper place]] If you can see the o-ring when tightend it sounds like it is not inserted properly!

 

Same replies I gave on TWO other forums and emails

Proper looks like this, O ring inside.

Bazzle


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@lwbrewer

Quote. "O-ring seals if two surfaces touch and the o-ring fills a 45* chamfer or inside the cylinder, that tighting tighter does not compress the O-ring any more."

Firstly the O ring needs to be correctly fitted. If however it is correctly fitted I reiterate that "finger tightening + 1/4 turn is not enough to correctly seat the cover especially if the O ring is dry.

The O ring IS compressed to some extent in order to give an adequate seal within the design groove and this compression takes place as the cover begins to seat thus increasing the torque and making finger tightening insufficent to properly seat the cover.
1/4 turn is not an appropriate way of gauging the torque of the cover which should be tightened to the correctly as stated on either the cover or the manual.

Bottom Line. If the O ring is showing it is incorrectly fitted.

 

sorry for the poor quality pic, taken with my phone.

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sanceki agree the o-ring must be fitted correctly and I have never seen a product that wanted a sealing o-ring put in dry. To clarify better on tightening. Once two metal surfaces meet trying to turn it tighter will not aid in sealing, but only to distort the metal. There our some o-ring seals that are full compression/ metal does not meet metal such as a screw on oil filter were a 1/4 turn still doesn't have metal to metal and it also is not a o-ring but a rubber washer

 

Good picture but it appears that the o ring in the pic is not correctly seated at the point nearest the camera.

if the o ring is not absolutely in its groove (or in fact too large (OD) it can "belly out and become trapped between the plastic and aluminium seating surfaces as the cover is tightened down.

 

I was suggesting that the o ring should be lightly oiled to assist during fitment. Not that it should be fitted dry. i.e. Dry fitment may cause a problem.

Quote: "Once two metal surfaces meet trying to turn it tighter will not aid in sealing, but only to distort the metal". Absolutely agree.

In addition I agree that not all rubber seals rely on a metal to metal / plastic coming together to CONTROL the degree of compression of the seal. A correct torque should however still be applied to ensure that the thread is neither damaged from overtightening or alternatively come loose thru vibration.

In both cases applying the correct torque is important unless you are sufficiently skilled that you are effectively your own calibrated torque wrench.

With disposable "can type" filters with a rubber washer the 1/4 turn process is a good guide since it removes variations in feel (torque) resulting from the amount of lubricant remaining o the sealing surfaces.