2018 Ford F-150 3.5L Plastic Oil Pan Leak: TSB 19-2346 Diagnosis & DIY Repair Guide

Ford F-150 2018 3.5L Plastic Oil Pan Leaking TSB: Why You Shouldn’t Pay a Mechanic (Yet)

If you’re a proud owner of a 2018 Ford F-150 with the 3.5L EcoBoost (or naturally aspirated) engine and have noticed a fresh, dark puddle under your truck, you’re not alone. A significant number of owners have faced oil leaks from a surprising source: the plastic oil pan. Before you call a mechanic and brace for a four-figure repair bill, there’s crucial information you need to know. Ford has officially acknowledged this widespread issue with a Technical Service Bulletin (TSB). This guide will walk you through diagnosing the leak, understanding the TSB, and executing the permanent fix yourself, saving you a small fortune in labor costs.

1. Diagnosis: Is Your F-150 Suffering from the Plastic Oil Pan Leak?

Accurate diagnosis is the first step. Don’t assume every oil leak is the pan. Here are the telltale symptoms of the specific Ford F-150 2018 3.5L plastic oil pan leaking TSB issue.

• The Oil Puddle Location: The leak will originate from the center-to-rear of the engine. Place a clean piece of cardboard or a drip pan under the engine overnight. In the morning, the oil will be roughly under the oil pan, not from the front (timing cover) or top (valve covers) of the engine.
• Visual Inspection: Safely lift and support the truck (using proper jack stands on solid ground). Clean the oil pan and the surrounding area with brake cleaner and a rag. Run the engine for a few minutes and then inspect with a flashlight. The leak will typically appear at the seam where the plastic upper pan meets the aluminum lower pan, or from the rear seal where the pan meets the transmission.
• The “Seeping” Not “Gushing” Leak: This is usually a seep, not a major gush. You’ll notice oil accumulating on the pan, transmission housing, and crossmember. Over time, it drips enough to hit the ground.
• TSB Confirmation: The official Ford TSB number for this issue is TSB 19-2346 (released November 2019). It specifically addresses “Engine Oil Leak At The Oil Pan” for 2017-2019 F-150s with the 3.5L engine. If your VIN falls within the range, this is your smoking gun.

2. Potential Causes: Why Does This Plastic Oil Pan Leak?

Ford’s move to a composite (plastic) oil pan was for weight savings and cost. However, the design proved problematic. According to the TSB and technician findings, the primary causes are:

• Faulty Silicone Sealant Application: The original factory sealant (RTV) between the two halves of the pan can fail. It may not have been applied evenly, may have cured improperly, or may simply degrade over time and heat cycles.
• Insufficient Torque on Pan Bolts: The bolts that clamp the two pan halves together may not have been torqued to specification at the factory, leading to uneven sealing pressure.
• Thermal Expansion & Stress: The plastic upper pan and aluminum lower pan expand and contract at different rates when heated and cooled. This constant flexing can break the sealant’s bond over time.
• Warpage: In some cases, the plastic upper pan itself can warp slightly, preventing a flat, secure seal against the lower pan or engine block.

Critical Note: The TSB does NOT recommend just resealing the original pan. Ford’s official repair procedure mandates replacement of the entire oil pan assembly with a revised part. This is the key to a permanent fix.

3. Step-by-Step Fix: The Permanent TSB Repair (Part # JL7Z-6675-E)

This is an intermediate-level DIY job. You’ll need a full day, a good tool set, and patience. The most important tool is a high-quality torque wrench. Never rely on “feel” for these bolts.

Tools & Parts You’ll Need:

• New Oil Pan Kit (Ford Part # JL7Z-6675-E – This is the updated assembly per TSB 19-2346)
• New Oil Filter and 6 Quarts of Motor Oil (Motorcraft blend or full synthetic 5W-30 recommended)
• Torque Wrench (inch-lbs and ft-lbs)
• Socket Set (8mm, 10mm, 13mm, 15mm are most common)
• Extensions, Universal Joint, and a Flex-Head Ratchet
• Oil Drain Pan
• Jack and (MOST IMPORTANTLY) Heavy-Duty Jack Stands
• Brake Cleaner & Lint-Free Rags
• Pry Bar (for stubborn transmission alignment)
• Threadlocker (Ford specifies TA-30, but medium-strength blue Loctite 243 is acceptable)

The Repair Procedure:

Step 1: Preparation & Draining. Park on a level surface. Disconnect the battery negative terminal. Safely lift the front of the truck and secure it on jack stands. Remove the skid plate (if equipped). Place your drain pan and remove the drain plug from the lower aluminum pan section. Once drained, remove the oil filter.

Step 2: Access & Disconnection. You need to separate the transmission from the engine slightly. Support the transmission with a jack and a block of wood. Remove the bolts securing the transmission bellhousing to the engine block (usually 6-8 bolts). Carefully lower the transmission jack about 1-2 inches. This provides critical clearance to remove the oil pan.

Step 3: Oil Pan Removal. Unbolt the 10mm bolts securing the oil pan to the engine block. There are many (around 20+), and some are hidden and require extensions and a universal joint. The pan will be stuck on with the old RTV. DO NOT PRY BETWEEN THE ENGINE BLOCK AND PAN. You can gently tap with a rubber mallet or use a flat blade between the upper and lower pan halves to break the seal. Once free, lower the pan and maneuver it out past the transmission. It’s messy.

Step 4: Surface Preparation (The Most Important Step). Thoroughly clean the engine block sealing surface. Use a plastic scraper or razor blade held at a shallow angle to remove all old RTV. Follow up with brake cleaner and lint-free rags until the surface is perfectly clean and dry. Any debris will cause a new leak.

Step 5: New Pan Installation. Your new JL7Z-6675-E kit comes with the pan pre-assembled with a new seal. Do not take it apart. It also includes a new dipstick tube O-ring—install it. Apply a small dab of threadlocker to the threads of each new bolt. Carefully position the new pan and start all bolts by hand.

Step 6: Torque Sequence. This is non-negotiable. Using your torque wrench in inch-lbs, follow this pattern:

1. Tighten all bolts in the sequence shown in the TSB (typically criss-cross from center out) to 35 INCH-LBS.
2. Go through the sequence again, tightening each bolt to 71 INCH-LBS.
3. Finally, go through the sequence a final time, tightening each bolt to 106 INCH-LBS (which is 8.8 ft-lbs).

Step 7: Reassembly. Raise the transmission back into position and install the bellhousing bolts. Torque these to Ford specification (typically 35-40 ft-lbs). Reinstall the skid plate. Lower the truck. Install a new oil filter. Add approximately 6 quarts of new oil.

Step 8: Final Checks. Reconnect the battery. Start the engine and let it run for a few minutes. Check for immediate leaks. Turn off the engine, wait a minute, and check the oil level, adding if necessary. Drive the truck gently for a day, then re-check for leaks and the oil level one final time.

4. Cost Estimates: DIY vs. Mechanic – The Staggering Difference

This is where knowing about the Ford F-150 2018 3.5L plastic oil pan leaking TSB saves you serious money. The job is overwhelmingly labor.

• DIY Cost (Parts & Supplies):
  • Oil Pan Kit (JL7Z-6675-E): ~$250 – $350 (online retailers)
  • Oil & Filter: ~$50 – $70
  • Brake Cleaner, Rags, etc.: ~$20
  • Total DIY Cost: ~$320 – $440
• Dealership/Mechanic Cost (Parts & Labor):
  • Parts (Pan, Oil, Filter): ~$400 – $500 (marked up)
  • Labor: 6.0 – 8.0 Hours (at $150-$200/hr shop rate)
  • Labor Cost: ~$900 – $1,600
  • Total Professional Cost: ~$1,300 – $2,100+

The Verdict: By tackling this job yourself, you are saving a minimum of $1,000, and often over $1,500. The investment in a quality torque wrench and a day of your time pays for itself many times over. More importantly, you’ve performed the correct repair as specified by Ford’s own TSB, ensuring the leak is fixed permanently. Don’t pay a mechanic to do this (yet)—arm yourself with knowledge, the right part, and take control of your truck’s repair.

---