CAT 9Y4357 BREATHER A for 345C Caterpillar Part - WSTPARTS
WSTPARTS supplies the 9Y4357 BREATHER A, a CAT Engine System replacement part designed for Caterpillar 345C, 345B and 365B applications. It is categorized under Engine System. Every unit is fitment-verified before dispatch. Manual reference: 345C: BASIC ENGINE, group 229-2611, page 51; 365B: BASIC ENGINE, group 117-2749, page 35.
9Y4357 BREATHER A for Caterpillar 345C — Genuine CAT & Replacement Part
WSTPARTS supplies genuine CAT and OEM-equivalent direct-replacement BREATHER A (Part # 9Y4357). Designed for CAT 345C, 345B, 365B, C13, 345D equipment.
Compatible Models
Key Features
- ✔ 100% compatible with CAT 345C, 345B, 365B, C13, 345D
- ✔ Meets Caterpillar original quality and performance standards
- ✔ Genuine CAT lines: New Genuine / Cat Reman / Cat Classic | OEM-equivalent direct replacements
- ✔ Available for order, contact for lead time
Specifications
| Part Number (MPN) | 9Y4357 |
| Product Name | BREATHER A |
| Brand | CAT |
| Applicable Models | 345C, 345B, 365B, C13, 345D |
| Weight | 0.64 kg |
| Condition | New (Genuine CAT / OEM-equivalent direct replacement) |
| Warranty | 12 Months |
Where This Part Fits
Every row below is a real listing of 9Y4357 in the Caterpillar parts manual: the machine it is published under, the system it belongs to, the group number and the manual page. Use it to confirm the part against your own parts book before ordering.
| Machine | System | Group No. | Manual Page |
| 345C | BASIC ENGINE | 229-2611 | p.51 |
| 365B | BASIC ENGINE | 117-2749 | p.35 |
| C13 | BASIC ENGINE | 236-4570 | p.139 |
| 345B | BASIC ENGINE | 117-2749 | p.39 |
| C13 | BASIC ENGINE | 236-4570 | p.140 |
| C13 | LUBRICATION SYSTEM | 224-5540 | p.363 |
System Notes — BASIC ENGINE
The basic engine group covers the core structure and internals: cylinder block, cylinder head, pistons, rings, liners, connecting rods, crankshaft, bearings, camshaft and the gasket sets that seal them. These parts determine compression, oil pressure and power output. They wear gradually — rings lose tension, bearings show copper, liners glaze — and the first signs are usually blow-by from the breather, rising oil consumption, or a knock that gets louder as the engine warms. Replacing a basic engine part is a planned overhaul decision rather than a roadside fix, so matching the exact part number and serial number range matters more here than anywhere else on the machine.
System Notes — LUBRICATION SYSTEM
The lubrication system covers the oil pump, oil cooler, oil filter base, relief valves, dipstick tube, pan and the galleries that distribute oil to every bearing in the engine. It is the system that keeps metal off metal. Failures tend to be either pressure loss — a worn pump, a stuck relief valve, a collapsed filter — or contamination, where sludge and debris circulate and score bearing surfaces. Oil pressure that reads low at idle, a filter that comes out heavy, or oil that turns dark far sooner than usual are the signals. Parts in this group are replaced on measured oil pressure and lab results rather than on interval alone.
FAQ
Is 9Y4357 the right part for my machine?
Match the part number on your old part, or send us your equipment serial number — WSTPARTS verifies fitment free of charge for CAT 345C.
Genuine CAT vs direct replacement — what is the difference?
Genuine CAT covers three factory lines: New Genuine, Cat Reman (core exchange with core charge) and Cat Classic (brand-new economy line). OEM-equivalent direct replacements are non-CAT parts; grade and warranty are confirmed in the quotation.
Stock, shipping and warranty?
Lead time confirmed on request; we quote the fastest available option. Every order is covered by a warranty per quotation.
📞 Get a Quote: Contact the WSTPARTS parts team | Email: cat@wstparts.com
