CAT 3R6789 CAP NUT for C18 Caterpillar Part - WSTPARTS
The 3R6789 CAP NUT is a genuine and high-quality OEM replacement part compatible with Caterpillar C18, G3616 and G3608 equipment. It is categorized under Electrical System. Every unit is fitment-verified before dispatch. Manual reference: 3606: LUBRICATION SYSTEM, group 172-8021, page 85; C18: COOLING SYSTEM, group 197-8433, page 399.
3R6789 CAP NUT for Caterpillar C18 — Genuine & OEM Replacement Part
WSTPARTS supplies genuine and high-quality OEM replacement CAP NUT (Part # 3R6789). Designed for CAT C18, G3616, G3608, 3606, 3608, 3616, G3612, 325C equipment.
Compatible Models
Key Features
- ✔ 100% compatible with CAT C18, G3616, G3608, 3606, 3608, 3616, G3612, 325C
- ✔ Meets Caterpillar original quality and performance standards
- ✔ Genuine CAT parts with anti-counterfeit label | OEM alternatives with warranty
- ✔ Available for order, contact for lead time
Specifications
| Part Number (MPN) | 3R6789 |
| Product Name | CAP NUT |
| Brand | CAT |
| Applicable Models | C18, G3616, G3608, 3606, 3608, 3616, G3612, 325C |
| Weight | 0.14 kg |
| Condition | New (Genuine / OEM Equivalent) |
| Warranty | 12 Months |
Where This Part Fits
Every row below is a real listing of 3R6789 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 |
| 3606 | LUBRICATION SYSTEM | 172-8021 | p.85 |
| 3608 | LUBRICATION SYSTEM | 172-8021 | p.83 |
| C18 | COOLING SYSTEM | 197-8433 | p.399 |
| G3616 | LUBRICATION SYSTEM | 281-4163 | p.244 |
| 325C | HYDRAULIC SYSTEM | 179-5168 | p.579 |
| 3616 | LUBRICATION SYSTEM | 133-9637 | p.92 |
| G3608 | LUBRICATION SYSTEM | 030-7935 | p.154 |
| G3612 | LUBRICATION SYSTEM | 067-9921 | p.89 |
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.
System Notes — COOLING SYSTEM
The cooling system covers the radiator, water pump, thermostat, fan and fan drive, coolant hoses, clamps, the surge tank and the belts that drive it. It holds engine temperature inside the range where clearances and oil film stay correct. Failures are usually slow and then sudden: a hose softens and balloons before it bursts, a water pump seal starts weeping from the weep hole, a thermostat sticks partly open so the engine runs cold and burns more fuel. On construction sites the radiator also packs with dust and debris, which raises pressure across the core and finds the weakest hose or clamp first.
FAQ
Is 3R6789 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 C18.
Genuine vs OEM replacement — what is the difference?
Genuine CAT parts carry an anti-counterfeit label. OEM equivalents are built to the same specifications, bench-tested and supplied with full warranty at a better price.
Stock, shipping and warranty?
Lead time confirmed on request; we quote the fastest available option. Every order is covered by a 12-month warranty.
📞 Get a Quote: Contact the WSTPARTS parts team | Email: cat@wstparts.com
