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A basic factory cap does the job, but it doesn't give you much extra protection. Upgrade to an aluminum Hydro-Shield cap that seals out water and grit, while the clear lens lets you check lubricant before the next haul.
A standard oil bath or grease cap closes off the hub, but this Hydro-Shield cap gives you more protection and easier access for maintenance. Its aluminum construction, waterproof sealing system, clear viewing window, and side service port make it a substantial upgrade when you want more from the cap already on your axle.
Replaces the oil bath/grease cap, O-ring, and plug on these axles:
Cap is a replacement for these oil caps:
Water and road grit can work their way past a basic cap and contaminate the lubricant around your bearings. The O-ring, gasket, precision threading, and Hydro-Shield vent plug create a waterproof barrier around the hub. The red button in the vent plug works as a check valve, releasing built-up pressure while keeping water from entering through the vent. That extra protection matters when your trailer sees heavy rain, muddy job sites, road spray, or repeated trips to the boat ramp.
The crystal-clear window gives you a direct view of your oil or grease level, so a quick look can become part of your normal trailer inspection. During maintenance, the magnetic plug also gives you another useful checkpoint by collecting metal particles that can indicate unusual bearing or axle wear.
You don't have to remove the entire cap just to service the lubricant. The side access port gives you a direct place to add or drain oil or grease, reducing the amount of disassembly during routine maintenance and leaving the cap and its seals in place.
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Hi everybody. Andy here with etrailer. Let's take a quick look together at this Valcrum Hydro-Shield waterproof aluminum oil bath or grease cap for your 9,000 to 16,000 pound axles. Now with this, you're gonna be able to say goodbye to leaks and milky oil and all the headaches that come with water finding its way into your hub. A tight O-ring gasket and precision threading are gonna lock out water and road grime while the red button on the vent plug is going to work as a check valve. This is going to let built up pressure escape, but keeps water from ever getting in.
You're gonna be able to drive through thunderstorms, launch at the boat ramp, or tackle muddy job sites knowing that your bearings and hub are protected. The anodized aluminum and e-coat are gonna work together to resist corrosion. This is gonna stand up to rain, sun, salt, and snow year after year. And this is going to fit a range of axles and replace existing oil caps. And I have all of that information there for you on your screen.
And you can also refer back to this information on this product page if need be. So you see the what it fits there at the bottom, or at least the lower part of that graphic. I have the cap, the direct replacement for the oil cap information there as well. Now this also features a magnetic plug you can see right there, and that sits inside the cap. And what that does is that collects metal shavings and debris.
So when you check the plug during maintenance, you're gonna get an early warning about unusual bearing or axle wear. This is gonna let you catch small issues before they turn into expensive repairs. And in addition, this crystal clear window, it's gonna make it very easy to check your oil or grease level in seconds. You're just gonna take a look and know that you're running with the right amount of lubricant. That's gonna help you avoid surprise breakdowns.
You're gonna be able to top off the lubricant through the side access port, so there's gonna be no need to remove this cap or risk damaging your seals. You can save time, avoid the mess, and lower the risk of improper installation. The thread outer diameter is 3.75 inches. That includes everything that you see here. But if you do happen to have any other questions about this or anything else that we carry here at etrailer, don't hesitate to reach out because we do wanna be sure that you're getting exactly what you need. Well, again, my name is Andy. Thank you for joining me.
Customer Satisfaction Score:
72% were satisfied with this product
28% of customers were not satisfied
Ratings & Reviews
fast shipping great product
I cannot rate the product but shipping met my expectations.
I'm am looking forward to see if they work as advertised. I tow a 40'boat all the time and have had nothing but bearing problems. Water has been getting into the bearings rusting and destroying them. Staff was a great help as well.
Info for this part was:
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Kate F.
11/19/2025
You really can’t go wrong with Valcrum, David! The inventor actually visited our facility, and the attention to detail that goes into these is truly impressive. I can’t wait to hear your thoughts after a year of use! =) What kind of boat do you have, and what is your favorite body of water to go out on?