What Can I Use to Replace the Hydrastar 303 Oil Cap?
Updated 05/14/2026 | Published 05/13/2026
Products Featured in This Question
Question:
I want to replace the existing caps on my oil bath bearings. The existing plastic cap is marked Hydrastar 303. Will this Vlacrum Part No. VA45JR work as a replacement?
asked by: Phil
Expert Reply:
Hi Phil,
We do carry the Hydrastar Oil Cap and Plug for 7K and 8K axles that work for Hydrastar disc brake kits. If your Hydrastar disc brakes are rated for 7K, 7.2K, or 8K and have 2.25" spindles then this will work perfectly for you!
The Valcrum Universal Threaded Aluminum Oil Bath Cap for 6K to 9K axles part # VA45JR has the same thread outer diameter of 2.875" as the Hydrastar and is rated for similar capacities. As long as your current cap's thread outer diameter matches and the axle's weight capacity falls into it's range you can use either the Hydrastar or Valcrum oil cap as a replacement.
What is your axle capacity and the outer diameter of your current cap?
(click to enlarge)
(click to enlarge)
Product Page this Question was Asked From
Valcrum Universal Threaded Aluminum Oil Bath or Grease Cap for 6K to 9K Axles - Black
- Trailer Bearings Races Seals Caps
- Caps
- Oil Cap
- Threaded Grease Cap
- 2.88 Inch O.D.
- 2.88 Inch
- 6000 lbs Axle
- 7000 lbs Axle
- 8000 lbs Axle
- 9000 lbs Axle
- Valcrum
more information >
Continue Researching
- Q&A: What is Torque Spec for Castle Nut of Dexter 3,500 lb Axle
- Q&A: Can You Use 8,000 lb Leaf Springs On A 7,000 lb Axle?
- Q&A: Bulldog 12000 lb Powered Electric Jack Replacement Motor
- Q&A: Looking for Horse Trailer Door Latch Replacement
- Q&A: Measurement on Dexter Axle 7-Leaf Slipper Spring w/ Hook End for 8,000-lb Trailer Axles
- Q&A: Can I Use a Kodiak Caliper with a DeeMaxx 12" Rotor?
- Q&A: Replacement Aluminum Wheels and Tires 205/75R15 With 5 on 4-1/2 Bolt Pattern
- Article: Replacing the Bearing, Races and Seals on a Trailer Hub
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Article: Trailer Brakes Not Working? Troubleshooting Guide
- Article: Trailer Wiring Diagrams
- Article: Parts Needed to Add Electric Drum Brakes to a Trailer