New 5J4988 Seal AS Replacement suitable for Caterpillar Equipment
- New Seal AS Replacement suitable for Caterpillar Equipment
- Made to USA Specification
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Description for 5J4988 Hyd Piston Seal
â–¶Specification for 5J4988 Hyd Piston Seal
â–¶Exact Fit Guarantee for 5J4988 Hyd Piston Seal
â–¶| Dimensions | 5.71x5.71x0.39 |
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Great prices prompt courteous customer service and fast shipping.
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A Delay Handled the Right Way
Honestly, if I were in Miami like my shipment was, I wouldn?t have been in a hurry to ship out either. I was frustrated at first ? delays cost me time on the job ? but Propel Parts stepped up.
Deb, Daniel and the team owned the mistake, kept the communication clear, and graciously refunded my shipping costs without making it a hassle. That kind of accountability is rare these days, and I genuinely appreciated how they handled it.
Things don?t always go perfectly, but these folks proved they?re more interested in doing right by their customers than just pushing parts out the door. Solid company, solid people.
? Jimmy Spong
Hartco Mobile Welding
P.S. Incredible quality on the pin as well. I had to do some custom modifying, and let?s just say the case hardening was ? well ? hard. Great Stuff! Thank you. -
Customer service was excellent today! I have never had a company go behind the scenes to see what was happening with my payment error and resolve it so I could complete my order without having to do it all over again. Hats off to Propel Parts!
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Great pricing and fast shipping!
I'll admit that I was skeptical of propel parts, but they are an honest site and came through with the order. I was skeptical because I've never ordered heavy machinery parts, and didn't know who to trust. The parts that I ordered showed in stock, but after checking with their vendor, they only had half of the order in stock. I was notified the day after the order, and most of the parts arrived in a few days. There was one part that was not shipped putz but I was able to talk with who I assumed is the owner who rectified the situation and had the part overnighted to me.
I will say that communication speed could use a little work, but they will eventually get back with you. -
I’ve been ordering parts from propel for about 3 years & counting. I live in Hawaii where we have a hard time getting parts especially for decent prices with fast shipping. I've been 100% satisfied with the company and the customer service and will continue to use them. I recommend propel to everyone here in Hawaii and we are all happy to have you guys. Thank you!!!
Frequently Asked Questions
What is the 5J4988 seal used for?
The 5J4988 is a sealing component that blocks fluid leakage and keeps dirt and debris out of the assembly. Reliable sealing is key to maintaining pressure and protecting internal parts.
How do I install the 5J4988 seal?
Fitting the 5J4988 correctly comes down to clean surfaces and following the manual sequence. Work through these steps:
- Shut down and depressurize the system, then let it cool if needed
- Remove the old seal and clean the bore and shaft surfaces
- Inspect the sealing surface for scoring, pitting, or wear
- Lightly lubricate the 5J4988 as directed and fit it square to the bore
- Seat it to the correct depth without distorting the lip, then check for leaks
Which Caterpillar machines is the 5J4988 compatible with?
Compatibility for the 5J4988 seal varies by machine and configuration, so cross-check it for your Caterpillar equipment before ordering. If you are unsure don't hesitate to reach out to Propel Parts for help verifying fitment.
Does the 5J4988 seal meet performance standards?
Yes. The 5J4988 is engineered to meet OEM specifications for material, dimensions, and durability. When replacing, choose genuine or high-quality aftermarket parts that meet or exceed OEM specifications so the part performs the way it was designed to.
How often should the 5J4988 be replaced?
The 5J4988 is typically renewed during scheduled service or a related repair. In demanding, high-hour operation, inspect it more often to stay ahead of wear.
What are the signs of a worn or failing 5J4988 seal?
When the 5J4988 reaches the end of its service life, the symptoms tend to show up first as performance or wear issues. Look for:
- Visible fluid leaks or seepage at the joint
- Loss of system pressure
- Contamination found inside the assembly
- A hardened, cracked, or torn sealing surface
Why is the 5J4988 important, and what related parts work with it?
Replacing the 5J4988 when needed keeps the system within its designed clearances and loads, which extends the life of the surrounding parts and supports dependable performance. Related hardware on our site includes 5P9890 Seal O-Ring and 2N7174 Gasket.

We know equipment downtime costs money, so fast and reliable shipping is a priority at Propel Parts. Orders placed on weekdays before 3:00 PM ET typically ship the same day, with expedited delivery options available for many locations when time is critical.
We ship across the U.S., Canada, and over 130 countries worldwide, helping customers keep machines running wherever they operate. Available shipping methods and delivery estimates are shown at checkout so you can select the option that best fits your timeline.
Tracking information is emailed within 24–48 hours after your order is processed, giving you full visibility from dispatch to delivery and peace of mind that your parts are on the way.

Our refund policy is simple. We offer a 30-day, no-hassle return policy, and we make every effort to provide the best service and highest-quality parts possible. If you’re not fully satisfied with your purchase, you may return it within 30 days for a refund. Full details are available on our Returns Policy page.

Buy with confidence. All parts from Propel Parts are covered against material or manufacturer defects for 12 months from the original invoice date. We stand behind every part we sell, so you can count on reliable performance and dependable support. Full details are available on our Warranty Policy page.
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