3CX, 4CX
Telescopic Handlers, Wheeled Loaders, JS Excavators, Mini Excavators, TELETRUK, Forklifts, Generators, FASTRAC
The expansion tank cap is not just a lid. It is a precision pressure valve that maintains a positive pressure (here: 1 Bar / 15 PSI) in the cooling system. This raises the boiling point of the coolant, protecting the engine from overheating. If your engine is overheating, coolant is being pushed out of the hoses, the hoses are rock hard (too much pressure) or too soft (no pressure), or you see dried coolant stains around the cap, these are classic symptoms of its failure. A faulty cap is a direct path to engine overheating and a blown head gasket.
Never open the cap on a hot engine! The system is pressurized and can spray hot coolant, causing severe burns.
When replacing the cap, check the coolant level and condition. If it's dirty, replace it with new fluid, e.g., from the HYPTRON brand, to ensure optimal protection.
Before screwing on the new cap, carefully clean the thread and sealing surface on the tank of dirt and old coolant residue.
Tighten the cap until you hear a distinct "click" or feel strong resistance. This ensures the gasket is properly compressed and the system is sealed.
Answer: Yes, this is a very common cause. If the cap does not hold pressure, the coolant's boiling point is lowered, leading to overheating.
Question: Why is there dried coolant around my cap?Answer: This is a classic symptom of a worn or hardened gasket in the cap. It is unable to hold pressure and is venting coolant to the outside.
Question: Can I use a cap with a different pressure rating?Answer: Absolutely not. Using a lower pressure cap will cause overheating, while a higher pressure one risks damaging (leaks) the radiator, heater core, or hoses.
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Correct Pressure Control (1 Bar)
Protects engine from overheating
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Durable Materials
Long life and reliability
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Perfect Sealing
Guarantees pressure is maintained
The accuracy and quality of materials guarantee long and trouble-free use without the need for frequent replacement.
The cap is fully adapted to work with original JCB expansion tanks, ensuring a consistent and reliable repair.
A functional cooling system is the cheapest insurance for your engine. A new pressure cap restores its full efficiency.
If you are unsure whether the selected product is suitable for your machine, contact us and we will help you choose the right part and provide practical advice in minutes.
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Expansion tank cap - 1 bar, suitable for, among others: for JCB 3CX, 4CX, Telehandlers, TLT, fastrac tractors, JS200-230 and GX100-120 generators.

















