Tech Tip: Oil Leak Repair for 1990-’93 4.0L Ford V6 Engines – UnderhoodService

Tech Tip: Oil Leak Repair for 1990-’93 4.0L Ford V6 Engines

The 4.0L Ford V6 has been a problem engine for oil leaks for years. This engine has been used in the Aerostar, Explorer and Ranger pickups. The most common oil leak on 1990-'93 4.0L engines is often diagnosed as a rear seal leak, but in most cases, the problem is usually found to be the rear of the oil pan gasket.

The 4.0L Ford V6 has been a problem engine for oil leaks for years. This engine has been used in the Aerostar, Explorer and Ranger pickups.
figure 1
The most common oil leak on 1990-’93 4.0L engines is often diagnosed as a rear seal leak, but in most cases, the problem is usually found to be the rear of the oil pan gasket. Since 1990, when the 4.0L was first introduced, Ford redesigned the gasket twice and even the oil pan casting to eliminate the leaking issue.

The following installation tips from Canada Engines should help to prevent this costly and aggravating oil pan gasket leak.

The ’90 to ’93 gasket set will include a plastic wedge seal that goes into a groove in the main cap. The diagram (Figures 1 – 5) explains the steps to take for a successful installation.
figure 2 - the 1990 to 1993 model years use gasket a along with the wedge seal b (figure 3) on the rear main cap.
Source: Canada Engines LTD.
figure 3 - use gasket a (figure 2) along with the wedge seal b on the rear main cap.figure 4 - the oil pan was redesigned in 1994 and so was the gasket shown c. the wedge seal is no longer used because its shape is built into the gasket. silicone is still necessary across the main cap and in the cavities between the cap and the block.Figure 5 - The oil pan must be aligned with a straight edge to the back of the block before it is torqued down.


You May Also Like

Tools To Service Serpentine Belts

Servicing the serpentine belt on some vehicles is a tough task.

Servicing the serpentine belt on some vehicles is a tough task. Without the right tools it is almost impossible. Here are six tools your shop needs to make your next belt replacement more productive.

Don’t Fight It
If you are still fighting belt tensioners with 3/8” breaker bar and wrenches, there are better solutions. There are serpentine belt kits that can help you get the right angle and attachment point on a tensioner to remove the old belt and install the new belt.

Battery Charging and Diagnostics

Here are six tips to use when diagnosing a vehicle with a dead battery. 

Why Do Timing Chains Stretch?

As the timing chain wears, it can change the timing of the camshaft and crankshaft.

Carbon Deposits and Direct Injection Engines

The primary cause of these problems is that fuel and added detergents are not hitting the back of the intake valves.

Acura Turbo Engine Service

It is important to check the operation of the solenoids that control vacuum to the actuators.

Other Posts

Subaru EJ25 Head Gasket Problems

Most of the EJ head gasket failures occur around the 100,000-mile mark and start as a slow oil or coolant leak.

Honda Electronic Throttle Body Service Tips

Using care and following OEM procedures will help you to avoid unnecessary parts replacement and comebacks.

New Oil Specifications

Many 0W16 oils have a new donut certification mark on the bottle called API SN-PLUS and SN-PLUS Resource Conserving.

Solving Intermittent Overheating

New cooling systems anticipate and influence changes in coolant temperature.