Understanding and Maintaining the NV4500 Transmission Top Cover

Understanding the NV4500 Transmission

The NV4500 is a heavy-duty, manual transmission that was used in Dodge Ram 2500 and 3500 trucks from the mid 1990s up until 2005. This transmission is revered for its durability and reliability in high torque, heavy hauling situations. However, like all transmissions, the NV4500 requires proper maintenance and care for optimal performance.

The NV4500 Top Cover

One key component of the NV4500 transmission is the top cover. This metal cover sits on top of the transmission housing and serves several important functions:

• Seals in transmission fluid
• Provides mounting points for shift towers, forks, and rails
• Gives rigidity and strength to the transmission case

The NV4500 top cover uses a gasket and RTV sealant to prevent transmission fluid leaks. Over time, this seal can wear out, crack, or rip, allowing fluid to leak from the transmission. Catching these leaks early and replacing the top cover gasket is critical to preventing damage and expensive repairs.

Identifying Top Cover Leaks

The most obvious sign of an NV500 top cover leak is pools of transmission fluid underneath your Dodge truck where it is parked. The fluid may be bright red or brown in color. Carefully inspect the transmission case and the mating surfaces between the top cover and case to pinpoint the exact source of any leaks.

Leaks often occur at the sealing surfaces between the cover and case. The gasket can get brittle or torn over years of engine vibration, allowing fluid to seep through. Cracks in the cover itself can also lead to leaks. Make sure to replace any leaking seals or damaged cover components.

Replacing the Top Cover Gasket

If you have identified leaks from the NV4500’s top cover seal, the gasket will need to be replaced. Here are the basic steps involved:

1. Drain transmission fluid
2. Disconnect shift linkages, towers, etc.
3. Unbolt and remove top cover
4. Thoroughly clean sealing surfaces on cover and case
5. Install new top cover gasket
6. Reinstall top cover with fresh RTV sealant
7. Reconnect shift components
8. Refill transmission fluid

Be prepared for some transmission fluid spillage when removing the top cover. Work slowly and take plenty of photos for reference during re-assembly. Using a factory service manual for your truck can also help during this repair.

Maintaining Your NV4500 Top Cover

With the NV4500 top cover resealed, be diligent about checking for leaks over the next few weeks of driving. It can take some time for new sealant to fully cure. Keep an eye out for continued seeping fluid.

Here are a few other tips for keeping your NV4500 top cover in good working order:

• Use only OEM or high quality aftermarket gaskets
• Check fluid levels regularly
• Change transmission fluid per factory recommendations
• Use proper RTV sealant at the cover’s seam

By properly maintaining the NV500 transmission’s top cover, you can get many more years and miles out of this durable manual gearbox.

FAQs

What are common causes of NV4500 top cover leaks?

The most common causes are a failed or damaged top cover gasket, cracks in the cover itself, stripped bolt holes allowing fluid to leak through, and failure of the RTV sealant over time.

Where exactly does transmission fluid leak from on the NV4500 top cover?

Fluid typically leaks from the mating surfaces between the top cover and transmission case where the gasket sits. It may also leak from cracks in the cover itself or the bolts holding the cover in place if the threads are damaged.

How do I remove the NV4500 top cover to replace the gasket?

You need to drain all transmission fluid, disconnect any shift linkage rods and brackets, wiring connectors, and then unbolt the top cover carefully. Be prepared for some residual fluid spillage as you remove it.

Can I drive with an NV4500 top cover leak?

It is not recommended to drive with any NV4500 leak. You risk losing all transmission fluid which can lead to major internal damage. Identify the leak source and repair it before operating your Dodge truck.