Frequently Asked Questions About Kenworth T800 Fuel Tank Caps

Will these fuel tank caps fit my specific year Kenworth T800?

Our Kenworth T800 fuel tank caps are designed to fit models from 1987 through current production years. However, there are two main thread sizes: 2-inch and 4-inch diameter. Most T800s from 1987-2006 use the 4-inch caps, while newer models may vary. We recommend checking your existing cap size or contacting us with your VIN for exact fitment verification.

What's the difference between vented and non-vented fuel caps?

Vented fuel caps allow air to enter the tank as fuel is consumed, preventing vacuum buildup that can cause pump damage or fuel flow issues. Non-vented caps create a sealed system. Most Kenworth T800s require vented caps for proper operation. Using the wrong type can trigger check engine lights or cause fuel system problems. Check your owner's manual or existing cap markings to determine which type you need.

Are locking fuel caps worth the extra cost for my T800?

Locking fuel caps provide essential theft deterrence, especially for owner-operators and fleet vehicles parked in unsecured areas. With diesel prices high, a quality locking cap typically pays for itself by preventing even one theft incident. Our locking caps come with two keys and maintain the same seal quality as standard caps. They add about 30 seconds to refueling but offer significant peace of mind.

How do I know when it's time to replace my fuel cap?

Replace your fuel cap if you notice: fuel smell around the tank area, visible cracks or damage to the rubber gasket, difficulty threading the cap on or off, check engine lights related to EVAP codes, or if the cap is more than 5 years old. A failing fuel cap can cause fuel economy loss of 1-2% and may not pass emissions testing in some states.

Can I install an aftermarket chrome or aluminum cap without issues?

Yes, our chrome and aluminum fuel caps maintain OEM specifications for proper sealing and venting. They use the same high-quality gaskets and threading as standard caps. Installation is identical to stock caps - simply unscrew the old cap and thread on the new one hand-tight plus 1/4 turn. These upgraded caps actually resist corrosion better than painted steel versions, making them ideal for trucks exposed to road salt or coastal conditions.