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Nitrile (NBR) O-Ring Assortment Kit, Metric, ...: 
Universal Filter Strap Wrench for Oil, Fuel a...: Komatsu 723-30-90101 is the screw in main relief valve cartridge in bright steel with hex lock nuts on the adjuster, a threaded body with O ring and a drilled sleeve. It is used on Komatsu PC100-6, PC120-6 and PC200-5 excavators. This aftermarket version is made to the same mounting and connections as the original, so it fits where the old one came off.
Sold as one unit. Check the number on your old part, or in the parts manual for your machine, before ordering.
| Part Type | Main Relief Valve |
| Replaces | Komatsu 723-30-90101 |
| Machine | Komatsu PC100-6, PC120-6, PC200-5 |
| Position | Main relief, control valve |
| Type | Screw in cartridge |
| Fits | Komatsu PC100-6, PC120-6 and PC200-5 excavators |
| Condition | New, aftermarket |
| Stat. HS-Code | 848140 |
| Country of Manufacture | China |
Komatsu machines
Check the part number on your old unit before ordering.
| Komatsu Part No.(SPM Part No.) | Fits |
|---|---|
| 723-30-90101(SPM-HEP-5102) | Komatsu PC100-6, PC120-6 and PC200-5 excavators |
Slow or weak hydraulics
A main or port relief valve that opens early or will not seat dumps oil to tank: the boom, arm or swing slows and loses force. Check pump pressure at the test port first.
Overheating oil
A relief valve that leaks past its seat turns pump flow into heat, so the hydraulic oil runs hot during normal work.
Pressure that will not set
If adjusting the relief screw no longer changes the pressure, the spring, poppet or seat is worn and the cartridge needs replacing.
Matching the old valve
Match the full part number stamped on the old cartridge, and set the pressure to the machine's service figure after fitting.
We check what other aftermarket sellers charge for this same part. Their prices on the date we checked:
| Seller | Price | Checked |
|---|---|---|
| eBay, aftermarket seller | USD 73.14 | 2 Nov 2026 |
| FridayParts | USD 84.35 | 2 Nov 2026 |
| Fab Heavy Parts | USD 88.20 | 2 Nov 2026 |
| SINOCMP | USD 101.00 | 2 Nov 2026 |
| Buy Machinery Parts | USD 110.86 | 2 Nov 2026 |
| Spare Part Mart | USD 54.16 | Today |
Our price of USD 54.16 is 26% to 51% less than these sellers.
Found this part cheaper somewhere else? Send us the listing and we will beat it by 5% under our Price Beat Guarantee. Every order is also covered by our 30 day money back guarantee.
Yes, it was made for the Komatsu PC100-6, and 2 more listed under compatible equipment. Check the old relief valve is marked 723-30-90101 or one of the cross references, because makers change parts between serial ranges.
On the Komatsu PC100-6, it depends on hours and working conditions. Follow the machine service schedule, and change it when it shows wear rather than waiting for it to fail.
Leaks, noise, loss of performance, or visible wear compared with a new part. If in doubt, measure it against the sizes in the specifications.
Match the part number on the old relief valve to Komatsu 723-30-90101 or a number in the cross reference table. If the number is worn off, compare the sizes in the specifications.
Yes. Every order is covered by our 30 day money back guarantee. Keep it unused and in its packaging.
No. It is an aftermarket relief valve made to replace the Komatsu 723-30-90101. It is not made by the original manufacturer; the number only shows what it replaces.
Live rates for the quantity selected, delivered to your door. Confirmed at checkout.
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