Oil leaking from under the oil filter

During the operation of the car, many motorists notice an oil leak under the oil filter. This problem can be relevant both for owners of fairly old cars with high mileage, and for relatively new internal combustion engines.

In the first case, oil flows around the oil filter, because the oil pump of the lubrication system may not have a pressure reducing valve that does not allow excessive pressure in the system. Most often, the problem manifests itself after a cold start in winter, when the oil thickens in the crankcase of the power unit. The grease simply does not have time to pass through the filter, causing the oil to be forced out.

With modern engines, leaks for this reason are usually not allowed, since the presence of an overpressure relief valve in the design of modern systems eliminates this possibility. For this reason, oil leakage under the oil filter housing is a malfunction and becomes a reason for diagnosing the power unit.

In this article, we will talk about why oil is leaking from the oil filter, what to do if an oil leak is found under the cover or oil filter housing, and how to fix it.

Why oil flows from under the oil filter

To begin with, the list of reasons why oil leaks from the oil filter area is quite extensive. Most often, the culprit is the owner himself, who has not changed the oil filter for a long time.

• Contamination of the oil filter under certain conditions can lead to the fact that the performance is greatly reduced, the lubricant practically does not pass through the filter medium. At the same time, to protect against oil starvation of the engine, the filter design usually has a special bypass valve (allows oil to bypass the filter element), but it is impossible to exclude the possibility of failure during its operation.

In the event that the purity and “freshness” of the filter are not in doubt, errors could have been made during its installation. If a leak occurs immediately after replacing the filter, it is quite possible that the filter is not tightened enough or the housing is not twisted (in the case of a collapsible design). This indicates the need for a tightening. This procedure is done manually or with a special plastic key extractor.

A prerequisite can be considered the absence of effort when turning, since the constriction leads to a rupture of the sealing rubber and deformation of the sealing ring. In this case, it is necessary to replace the filter with a new one or solve the problem by replacing the damaged seal.

We add that very often during installation, car owners and mechanics forget to lubricate the old rubber o-ring on the oil filter housing with engine oil. This leads to the fact that after unscrewing the filter, it may become loose, the seal may be deformed or placed crooked.

In any case, the oil filter must be removed, the integrity of the seal checked, the rubber band lubricated and the filter element replaced, taking into account the peculiarities of its installation. It should also be remembered that a faulty oil filter can be found commercially. In such a situation, the housing itself may be defective, in which there are cracks, the seal may be made of low-quality rubber, the filter valve does not work, etc.

High engine oil pressure is the second most common cause of oil leaks around the oil filter. An increase in pressure in the lubrication system can occur for a number of reasons, ranging from significant thickening of the lubricant, coupled with excessive oil levels, to certain mechanical failures.

Let's start with the bypass valve. The specified valve is necessary to relieve oil pressure in case of exceeding the specified value. The valve can be located in the area of ​​the filter holder, as well as in the oil pump itself (depending on the design features). To check, you need to get to the valve and evaluate its performance.

If it gets stuck in the closed position, the element is not working. In this case, the device must be cleaned and rinsed. For cleaning, gasoline, carburetor cleaner, kerosene, etc. are suitable. Please note that, as practice shows, it is better to replace valves if possible, especially considering its relatively affordable price.

Another cause of an oil filter related leak is a problem with the threads of the fitting on which the filter is screwed. If the threads are stripped or damaged, the filter housing cannot be properly tightened during installation, and oil will leak out as a result. In such a situation, it is necessary to change the accessory or cut a new thread.

It is also worth noting that if the oil is selected incorrectly, that is, it becomes too liquid or viscous, then leaks often occur in the area of ​​gaskets and seals. The oil filter is no exception. Lubrication must be selected in accordance with the requirements of the vehicle manufacturer, and also take into account the characteristics and operating conditions.

Please note that if the driver constantly uses the same type of oil, the filter is not dirty, there were no significant changes in weather conditions, and there are no obvious engine malfunctions, then counterfeit engine oil may be flooded into the engine. It turns out that low-quality grease simply does not have the declared properties, which is why leaks appear.

The way out in this situation is obvious: it is necessary to immediately replace the filter and lubricant, and additional flushing of the engine lubrication system may also be necessary. Finally, we add that blockage of the pipes of the crankcase ventilation system causes the accumulation of gases inside the internal combustion engine, an increase in pressure inside the engine and oil leakage through gaskets and seals. The specified crankcase ventilation system should be checked during the diagnostic process, as well as periodically cleaned for preventive purposes.

How to fix an oil filter leak

So, in most cases, it is enough to fill in high-quality oil, taking into account the manufacturer's recommendations and seasonality, in order to properly change or install the oil filter.

With basic skills, it is quite possible to cope with cleaning the crankcase ventilation system. This means that in most cases, almost every driver in the garage can fix an oil leak with their own hands.

As for more complex breakdowns, these include a faulty pressure reducing valve and damaged threads on the oil filter mounting fitting. In practice, the problem with the valve is more common, so let's focus on checking it separately.

The main task is to check the valve spring, which is located under the plug. It is she who is responsible for the operation of the device, the overall performance will depend on the state of the spring. The specified spring must be removed from the sleeve for inspection. Scratches, wrinkles, folds and other defects are not allowed. Also, the spring should be tight, not loose.

If the spring is easily stretched by hand, this indicates a weakening of this element. In addition, the overall length of the spring should not increase, indicating stretch. A decrease in length indicates that part of the spring has broken. In this situation, it is also necessary to remove debris from the valve seat. Finding any defect in the spring is a reason to replace it.

To summarize

As you can see, there are many reasons for oil leakage in the oil filter area. It is necessary to check the engine in the process of phased diagnostics, that is, by elimination. In parallel with the search for a problem, you can measure the pressure in the lubrication system with a liquid pressure gauge, as well as measure the compression in the engine.

A decrease in compression in the cylinders will indicate a possible release of gases from the combustion chamber and an increase in pressure in the crankcase. Fluid pressure gauge readings will help you quickly identify pressure deviations in the lubrication system, if any.

Finally, we add that if oil flows out from under the oil filter during start-ups or the lubricant flows constantly, with the engine running and the pressure in the lubrication system is normal, and the filter itself is correctly installed and securely fixed., then the reason may be in the low quality of the filter itself. In this case, before overhauling the internal combustion engine, it is better to first change the filter to a proven product from a well-known manufacturer.