Oil still leaking after I changed oil filter

ANSWER : Hi There,
It sounds like you may need to replace the oil cap o-ring. If you haven’t done this before there are two O-rings to replace; a small green one on the base of the filter cap stem and the large black one that seals the filter cap (which seems to be the one you are having issues with). The large O-ring sits in a small square-shaped groove that is at the base of the oil filter cap. It is very easy to not properly seat the large O-ring because the threads for the oil cap are quite large and will accept the O-ring if you are not careful. I would suggest having a professional from YourMechanic come to your location to take a look at your vehicle.

ANSWER : Most older cars have oil leaks. Sealing technology has just not kept up with mechanical improvements to engines so much so that leaks often kill engines rather than mechanical problems. So, it is not unexpected at all to have an, indeed many, oil leaks on a 23 year old car. Oil leaks vary hugely in terms of severity and priority of repair. Oil leaking onto a hot engine manifold is the worst case (the oil can start a fire; at best, you are left breathing oil fumes in the cabin, as the oil burns off of the manifold) while de minimus seepage of oil at the oil drain plug or oil pan gasket, while annoying and messy, if limited enough is not an emergency. Some leaks are easy to repair, while others literally require the engine to be removed just to get physical access to all the leak points. In your circumstance, if you smell burning oil, oil is probably leaking onto a hot engine part such as the exhaust manifold. A certified Mechanic, dispatched by YourMechanic right to your location, can perform an oil leak diagnostic and then let you know of your repair options and costs.

As far as the check engine light, that is not related to the oil leak(s). If you request a check engine light diagnostic, a certified mechanic from YourMechanic would use a code scanner to retrieve the specific diagnostic trouble code(s) from your car’s PCM that have caused the check engine light to illuminate. Using those codes, the appropriate individual vehicle components or sub-systems (often a sensor, circuit, and the like) are then carefully tested, based on specifications set forth in your car’s Factory Service Manual, to pinpoint the cause of the fault or the reason why the check engine light has illuminated. Once the faulty part or component is identified, it is explained to your satisfaction and the mechanic will let you know of the cost to repair. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : Unless there is an imperfection (e.g., serious pitting or irregularities) on the engine mounting base for the filter gasket, the leak is probably not at the filter. There are other adjacent potential leak spots such as the oil pan gasket, oil pressure sending unit and so forth. If the leak is significant at all, merely thoroughly cleaning the suspect area and running the engine while looking for the leak should be sufficient. If you still can’t find the leak origin, a UV visible dye can be added to the engine oil which will then make the leak point visible using a detection light. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an oil leak diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : If the oil filter housing is integral to the oil cooler, or the housing had to be removed to service the cooler, a professional mechanic with knowledge of the limited service life of rubber seals would have absolutely (guaranteed) replaced the filter housing gasket that you are now belatedly finding leaks. However, if the leaking gasket is in an assembly that was not touched, or is not part of the cooler, they might be on reasonable grounds to have not fooled with it. These cooler configurations vary (from Mercedes Benz model to model) so, having the advice I just gave, you can just simply ask them what configuration you have and go from there. The bottom line is, if indeed, the gasket that is presently leaking was "right in front of them" while they did the warranty work, it should have been replaced simply as a matter of course. Indeed, the weak link on modern engines has become gaskets and seals. The engine will mechanically far outlast the gasket and seals but the problem is to replace all of them (once they all leak) you have to literally take the engine out of the car and take it apart just to put all new seals in. Please let us know how we can help further on this issue.

ANSWER : You might have a problem with the oil filter leaking when you rev the engine and increase the oil pressure. This can be from a collapsed oil filter media or excessive oil pressure from the engine. I recommend having the oil and filter replaced using a good quality filter and have the oil leak verified to be from the filter. Make sure to not run the engine low on oil. If you are finding you do not want to drive with the leak, a mobile technician from YourMechanic can come to your home or office, and replace both your filter, and oil.

ANSWER : There should be an oil pressure sensor located near the filter housing. Check to see if there is a leak at the sensor. At idle, there should be about 15PSI of pressure and about 50-60PSI at around 3,000 RPM’s. There should also be an oil cooler in the same area near the filter housing as well. Check it to be sure all of the inlets and outlets from this are also properly sealed. If you are not able to locate any leaks, I would suggest having an expert from YourMechanic come to the car to diagnose the oil leak firsthand and help you make the necessary repairs.

ANSWER : Oil additives are not recommended by any vehicle manufacturer for any reason. Additives that purport to resolve oil leaks are useless, a waste of your money, and may result in engine damage. Every vehicle manufacturer strongly recommends against use of these materials. There is only one recommended and approved repair strategy when it comes to oil leaks: fix the leak.

You can only add the manufacturer specified amount of oil to an engine. If you add too much oil, or too little oil, that will cause engine damage. You should check the engine oil dipstick to determine if there is presently too much oil in the engine. If there is too much, the excess will have to be removed to prevent engine damage.

The leak that you are referring to can be repaired if you request an oil leak diagnostic. If you have further questions or concerns as you decide what to do, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you get the best possible results.

ANSWER : Try checking all of the fittings near and around the oil filter housing as well as the oil pump. Check to be sure the correct O-ring is sealing correctly when the oil filter is screwed on as this is a common problem many experience when the O-ring gets smashed or does not seal correctly. If there the O-ring is non-existent as you mention, then this could likely be the source of this issue. If you need to have this taken care of, a qualified professional from YourMechanic can diagnose the oil leak and replace the O-ring for you if needed.