Battery Tray Leaks/Repairs – 2.5L NA

Overview

This procedure addresses leaks in the battery tray of a Porsche 944 (8-valve engine), which can cause water to damage critical components like the DME control unit in the passenger footwell. Leaks typically occur when the tray’s drain clogs or the battery cover is missing, allowing water to mix with battery acid and corrode the tray. This guide provides two repair methods: Method 1 for minor damage and Method 2 for significant damage requiring replacement of the tray bottom. Regular maintenance, such as cleaning the tray and checking the drain, is essential to prevent leaks.

Pink and blue text represent links to additional resources, tools, parts, and partner websites.

Tools Required

• 10mm (3/8 inch) wrench
• Metal scraper
• Gloves, mask, and eye protection
• Paintbrush for rust converter and seam sealer
• Cutoff tool, cutting torch, or plasma cutter (Method 2 only)
• Permanent marker, paint, or scratch awl (Method 2 only)
• Hand grinder (Method 2 only)
• Welding equipment (Method 2 only)

Parts Required

• Battery cover, 944 611 021 00
• Rust converter (e.g., Mar-Hyde or similar)
• Brushable seam sealer (e.g., 3M or similar)
• Primer (for bare metal)
• Paint (to match car’s color)
• Metal plate (carbon, galvanized, or stainless steel, Method 2 only)

Step-by-Step Procedure

Step 1: Remove the Battery and Inspect the Tray

1. Disconnect the battery terminals using a 10mm (3/8 inch) wrench and remove the battery from the tray.
2. Check the battery tray drain by pouring a cup of water into the tray. If it doesn’t drain quickly, clear any clogs with a small tool or compressed air.
3. Place rags under the tray to catch any leaks during cleaning.
4. Clean the tray with mild soap and water, removing debris like leaves. Rinse thoroughly.

Step 2: Assess Tray Damage and Choose Repair Method

5. Inspect the tray for holes or weak spots. Press the bottom to check for flexing.

– If there are no holes or only small ones, use Method 1 (Steps 3–6).

– If there are large holes or the bottom flexes easily, use Method 2 (Steps 7–10).

Step 3: Prepare the Tray for Repair (Method 1)

6. Follow this link to ensure this step – DME Control Unit Removal – is completed accurately to protect the DME control unit in the passenger footwell (applies to all 944 models with DME in the footwell).
7. Scrape the tray bottom with a metal scraper to remove loose paint.
8. Look for rust-colored discoloration or exposed rusted metal. For dark-colored cars, remove as much paint as possible to reveal hidden rust.

Step 4: Treat Rust and Seal the Tray (Method 1)

9. Wear gloves, a mask, and eye protection. Apply rust converter (e.g., Mar-Hyde) with a brush to rusted areas. Let it dry completely.
10. For bare metal, apply primer and let it dry.
11. Brush on a layer of brushable seam sealer (e.g., 3M) across the tray bottom, mimicking factory brush strokes for aesthetics. Let it dry.

Step 5: Paint and Reinstall (Method 1)

12. Paint the tray to match the car’s color. No primer is needed over the seam sealer. Let the paint dry.
13. Install the battery cover, 944 611 021 00, on the battery to prevent acid wash-off.
14. Reinstall the battery and reconnect the terminals using a 10mm (3/8 inch) wrench.

Step 6: Prepare for Replacement (Method 2)

15. Follow this link to ensure this step – DME Control Unit Removal – is completed accurately to protect the DME control unit in the passenger footwell (applies to all 944 models with DME in the footwell).
16. Mark the damaged area of the tray bottom using a permanent marker, paint, or scratch awl.
17. Cut out the marked area using a cutoff tool, cutting torch, or plasma cutter.

Step 7: Create and Install New Tray Bottom (Method 2)

18. Hold a sheet of paper against the tray bottom and trace the cutout area to make a template.
19. Transfer the template to a metal plate (carbon, galvanized, or stainless steel). Cut out the new bottom.
20. Tack weld the new bottom in place to secure it, then complete the welding.
21. Use a hand grinder to smooth the welds on the tray’s interior side.

Step 8: Seal and Paint New Tray Bottom (Method 2)

22. For bare metal, apply primer and let it dry.
23. Brush on a layer of brushable seam sealer (e.g., 3M) across the new tray bottom, mimicking factory brush strokes. Let it dry.
24. Paint the tray to match the car’s color. No primer is needed over the seam sealer. Let the paint dry.

Step 9: Reinstall Battery and Cover (Method 2)

25. Install the battery cover, 944 611 021 01, on the battery to prevent acid wash-off.
26. Reinstall the battery and reconnect the terminals using a 10mm (3/8 inch) wrench.

Step 10: Maintain the Battery Tray

27. Periodically remove the battery and clean the tray with mild soap and water.
28. Check the drain to ensure it’s clear by pouring water into the tray.

Post Procedure Checklist

• Verify the battery tray drain is clear and water drains quickly.
• Check for any remaining leaks by pouring water into the tray and inspecting underneath.
• Ensure the battery cover, 944 611 021 00, is installed.
• Confirm the DME control unit is undamaged and reinstalled correctly (if removed).
• Inspect the tray for uniform paint and seam sealer coverage.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manuals
• YouTube