Products Description
MS044 Oil Seal Set – 18x29.6x5/3 & 13x19x4 Crankshaft Seals for Stihl 044 & MS440
Complete Crankcase Seal Replacement Kit for Stihl Professional Chainsaws
This oil seal set includes the two essential crankshaft seals required for the Stihl 044 and MS440 chainsaws. The set consists of the clutch side seal (18x29.6x5/3mm) and the flywheel side seal (13x19x4mm), allowing for a complete sealing system replacement during engine maintenance. Replacing worn seals is crucial for maintaining proper crankcase pressure, preventing oil leaks, and ensuring reliable starting and stable idling.
Technical Profiles & Materials
Dual Seal Set – Includes both the PTO/clutch side seal (18x29.6x5/3mm, OEM 9640 003 1972) and the flywheel side seal (13x19x4mm, OEM 9640 003 1320) for a comprehensive crankcase sealing solution .
OEM-Spec Compatibility – Replaces genuine Stihl part numbers 9640 003 1972 (18x29.6x5/3) and 9640 003 1320 (13x19x4). Fits Stihl 044 and MS440 chainsaws .
Durable Construction – Features a robust metal outer case with a resilient rubber sealing lip, delivering a reliable seal under heat, vibration, and high engine speeds . The 18x29.6x5/3 seal measures approximately 0.71 x 1.17 x 0.20/0.12 inches .
Clutch Side Seal Specification – The 18x29.6x5/3 seal is designated for the PTO (clutch) side. The "5/3" dimension indicates a stepped profile where the seal is 5mm thick at the outer edge and 3mm at the lip area .
Technical Specifications
| # | Component | Specification |
|---|---|---|
| 1 | PTO/Clutch Side OEM | 9640 003 1972 |
| 2 | PTO Dimensions | 18 x 29.6 x 5/3 mm |
| 3 | PTO Also Replaces | 9640 003 1970, 9640 951 1972 |
| 4 | Flywheel Side OEM | 9640 003 1320 |
| 5 | Flywheel Dimensions | 13 x 19 x 4 mm (approx.) |
| 6 | Material | Metal outer case + rubber sealing lip |
| 7 | Compatible Models | Stihl 044, MS440 |
| 8 | Installation Note | Clutch side seal requires tapered bushing for proper installation over crankshaft shoulder |
Products Application
Crankshaft Seal Replacement
Worn seals on the 044/MS440 can cause air leaks, leading to lean running conditions, hard starting, and erratic idling. Replacing both seals simultaneously ensures proper crankcase sealing and prevents unmetered air from entering the engine .
Engine Overhaul & Rebuild
During a top-end or full engine rebuild, replacing both oil seals is standard practice. The 044 uses different seal mounting positions: the clutch side seal mounts into the bearing extension, while the flywheel side seal fits into the case . The set provides all necessary sealing components for a complete crankcase restoration.
Oil Leak Resolution
Visible oil seepage around the crankshaft area indicates seal failure. Replacing with this set stops oil loss, protects internal components, and maintains proper crankcase pressure for consistent power output .
Quality and Craftsmanship Details
Products Package
About Us
As a premier garden machinery parts supplier, Jiaxing Norsun Trading Co., Ltd. bridges global distributors with over 100 vetted China manufacturers. We streamline your B2B supply chain through strict quality control, flexible production, and factory-direct wholesale pricing. Partner with us for reliable, high-volume sourcing of precision-engineered outdoor power equipment components.
Trusted Partnership Power
YOUR PROFESSIONAL ONE-STOP SOURCE
FOR 10000+ OUALITY PARTS
Verified Factory Excellence
BACKED BY 200+ TRUSTED FACTORY PARTNERS
Production process
Quality control
Expo experience
Customer Reviews
FAQ
Q: What is the difference between the two oil seals in this set?
A:The 18x29.6x5/3 seal is for the clutch/PTO side and features a stepped thickness (5mm outer, 3mm lip). The 13x19x4 seal is for the flywheel side and has a uniform 4mm thickness. These seals are specifically positioned for the 044/MS440 crankcase design and are not interchangeable .
Q: Why are there two different OEM numbers for the 18x29.6x5/3 seal?
A: Stihl part numbers 9640 003 1972 and 9640 951 1972 refer to the same 18x29.6x5/3 seal. The different numbers may indicate different production batches or packaging variants. Both fit the 044 and MS440 .
Q: What special tools are needed for installation?
A: The clutch side seal requires a tapered bushing to slide over the crankshaft stub without damaging the garter spring behind the seal lip. Professional installation is recommended for proper seating . Using the wrong technique can damage the new seal and cause premature failure.
Hot Tags: ms044 oil seal 18x29.6x5/3 13x19x4, China ms044 oil seal 18x29.6x5/3 13x19x4 suppliers, ms440 ms460 parts, MS044 MS440 Worm Gear E clip, MS044 Oil Seal 18X29 6X5 3 13X19X4
