Here are some of the most likely culprits:
* Valve Cover Gasket: This is a common source of oil leaks. A worn or damaged valve cover gasket allows oil to seep from the top of the engine. Gravity will often lead some of this oil to drip onto the exhaust manifold.
* Rear Main Seal: This seal prevents oil from leaking from the rear of the crankshaft. A leak here can be difficult to spot initially, but oil will often travel down the engine and eventually reach the exhaust. This is a more significant repair.
* Oil Pan Gasket: A leak from the oil pan gasket will allow oil to drain from the bottom of the engine. While this is less likely to directly drip *onto* the exhaust manifold (unless it's a very significant leak), oil can travel along the underside of the engine and end up there.
* Crankshaft Seal (Front): Similar to the rear main seal, a failing front crankshaft seal can leak oil, leading to it dripping onto hot components including the exhaust.
* Head Gasket: While less common to cause a leak directly onto the exhaust, a severely damaged head gasket can allow oil to mix with coolant or get pushed out under pressure, potentially finding its way to the exhaust. This is a serious issue.
* Oil Pressure Sending Unit: While not a large leak, a faulty oil pressure sending unit can seep oil.
To diagnose the problem:
You'll need to inspect the engine carefully. This may require cleaning the engine thoroughly (with a degreaser) to see where the oil is actually coming from. Once clean, run the engine for a short time and look for fresh oil leaks. A mechanic's inspection light or a flashlight will help you see difficult to reach places.
What to do:
1. Stop driving the vehicle immediately. Driving with an oil leak on the exhaust is extremely dangerous.
2. Have a qualified mechanic diagnose and repair the leak. Trying to fix this yourself without experience can be problematic. Ignoring it can lead to engine damage or fire.
3. Don't attempt to just "top off" the oil. The underlying problem needs to be addressed.
A mechanic will be able to pinpoint the source of the leak and recommend the best course of action. The repair cost will vary considerably depending on the cause of the leak.
