1990 BMW 735i Is Leaking Oil

Diagnosing Oil Leak Sources in Your 1990 BMW 735i and Effective Repair Strategies

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Reviewed by
Devin Cabugcal
Written by RepairPal Car Genius
Updated January 14, 2025
0%
80% chance it's the
Oil System Components
0%
20% chance it's the
Engine Gaskets
The most common reasons a 1990 BMW 735i is leaking oil are oil system component failure and leaking engine gaskets.
  • Oil System Components: A worn or damaged oil pump or filter can lead to low oil pressure, resulting in inadequate lubrication and potential engine damage.
  • Engine Gaskets: A worn or damaged engine gasket can lead to oil or coolant leaks, resulting in engine overheating or loss of lubrication.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 1990 BMW 735i is leaking oil?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

The engine oil pressure warning light will come on if the engine oil pressure is low, or if the oil pressure sensor is faulty. In either case, engine power may be reduced significantly. The check engine light may also illuminate, and an on-board diagnostic (OBD) trouble code will be stored in the vehicle's computer.

What are the steps to diagnose the oil leak in a 1990 BMW 735i?

To effectively diagnose an oil leak in your 1990 BMW 735i, begin by identifying the source of the leak, as this will guide your inspection process. Start with the valve covers, transmission, and differential seals, which are common culprits in older BMW models. Carefully inspect these areas for any signs of oil accumulation or dripping. If you notice oil around the oil filter, check the oil filter gasket; it may simply need tightening or replacement. Additionally, look for oil pooling under the transmission, which could indicate a rear main seal or oil pump issue. Don’t overlook the engine mounts, as liquid-filled mounts can also leak oil. By systematically checking these key areas, you can pinpoint the source of the leak and determine the necessary repairs, ensuring your BMW runs smoothly and efficiently.

What are the common causes of oil leaks in a 1990 BMW 735i?

When dealing with oil leaks in a 1990 BMW 735i, it's essential to understand the common problems that can arise. One of the primary culprits is worn or damaged gaskets and seals, particularly the valve cover gasket and oil filter housing, which are notorious for causing leaks in BMW engines. Regular maintenance is crucial; neglecting oil changes can lead to oil degradation, increasing the likelihood of leaks. Additionally, simple oversights, such as failing to securely tighten the oil cap, can also result in oil escaping from the engine. By being aware of these potential issues, DIY enthusiasts can take proactive measures to inspect and maintain their vehicle, ensuring that any signs of leaks are promptly addressed to avoid more severe engine problems down the line.

How urgent is it to address the oil leak in my 1990 BMW 735i to prevent potential engine damage and safety risks?

Addressing an oil leak in your 1990 BMW 735i is an urgent matter that should not be overlooked. The longer you wait to fix the leak, the greater the risk of severe engine damage due to inadequate lubrication, which can lead to costly repairs and a decrease in vehicle performance. Additionally, oil leaks can create hazardous conditions, as oil buildup around the engine and other components can result in slippery surfaces, increasing the likelihood of accidents. Financially, delaying repairs can escalate costs significantly, as minor leaks can develop into major issues requiring extensive work. Therefore, it is crucial to act swiftly to mitigate these risks, ensuring both your safety and the longevity of your vehicle.

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1990 BMW 735i Oil Leak Causes & Repair Costs | RepairPal