4JJ1 Cylinder Head Assembly for Isuzu Excavator and Industrial Diesel Engines
This is a complete 4JJ1 cylinder head assembly: the head casting is supplied with valves, valve springs, retainers and camshaft fitted, so the workshop bolts it down and sets the timing instead of rebuilding a cracked or warped head by hand. It is the usual answer when the original head has dropped a valve seat, cracked between the injector bores, or been skimmed too many times after repeated gasket failures. The head is pressure tested for porosity and checked for flatness before it leaves the workshop.
Head Specifications
| Item | Detail |
|---|
| Engine model | 4JJ1 |
| Part name | Cylinder head assembly |
| Engine type | 4-cylinder, overhead cam, water cooled diesel |
| Displacement | 2.999 L |
| Bore x stroke | 95.4 mm x 105 mm |
| Head material | Cast iron, machined deck |
| Condition | New aftermarket assembly, pressure tested |
| Packing | Timber case with foam support, deck protected |
What the Assembly Includes
- Cylinder head casting with valve guides and seats in place
- Intake and exhaust valves, springs, retainers and keepers
- Camshaft fitted in the head with caps and bearing journals checked
- Valve stem seals and camshaft oil seals
- Deck surface machined and flatness verified
What Is Not Included
- Head gasket and head bolts (supply separately or add to the same order)
- Injectors, injector pipes and fuel lines
- Glow plugs, sensors and wiring
- Timing chain, tensioner and covers
- Intake and exhaust manifolds, turbocharger
Why This Head Works for Repair Shops
- Pressure tested casting — the head is checked for porosity and internal cracks, the most common cause of coolant loss and white smoke after a rebuild
- Valve work done — seats are cut and valves lapped, so compression is even and the engine starts without a long crank
- Camshaft fitted and checked — journals are verified in the head, which avoids the binding and noise that comes from mixing a used cam with a new casting
- Deck flatness verified — keeps the gasket sealed, which is what repeated gasket failures on overheating engines are really about
- Bolt-on repair — no machining on site, and the head matches the original mounting, port and injector bore layout
Typical Symptoms That Call for a New Head
- White smoke and coolant loss with no external leak
- Bubbles in the radiator or pressure building in the cooling system
- Repeated head gasket failure, especially after an overheating event
- Cracked head between valve seats or injector bores
- Valve noise, burnt valve or dropped seat
- Coolant and oil mixing, or emulsion in the sump
Installation Notes
- Confirm the engine plate reads 4JJ1 before ordering; where the engine has been replaced before, send photos of the plate and both sides of the old head
- Check the deck of the block for flatness and clean the bolt holes; do not reuse torque-to-yield head bolts
- Use a new head gasket, follow the manual torque sequence in stages, and set the camshaft timing to the marks before turning the engine over
- Ream or clean the injector seats and fit new copper washers so combustion gas cannot escape past the injector
- Refill with the correct coolant, run up to temperature, then recheck torque and valve clearance after the first 50 hours
Packing and Shipping
The head is wrapped in anti-rust film, foam supported on the deck and manifold faces, then fixed inside a timber case. We send packing photos and the packing list before dispatch and can ship by express for single units or by sea for workshop orders.
FAQ
Q: Is the camshaft included?
A: Yes, the assembly is supplied with the camshaft, valves, springs and seals fitted. If you need a bare head only, tell us and we will quote that option.
Q: Is it a genuine Isuzu part?
A: It is a new aftermarket assembly built to 4JJ1 dimensions, priced below genuine units while keeping the same port layout, injector bores and mounting points.
Q: Does it include the head gasket and bolts?
A: No. Gasket kits and head bolt sets are treated as separate items because bolt type varies by build; we can add them to the same shipment.
Q: What is the warranty?
A: Three months against casting defects and assembly work, provided the torque sequence and coolant specification in the installation note are followed.
Q: How long is the lead time?
A: Usually 3 to 7 working days for stock heads and 15 to 25 days for production orders, depending on quantity.
Regional Buyer FAQ
North America and Europe
Q: Do you supply CE or EPA documents?
A: The head is a replacement component, so machine-level CE or EPA certificates do not apply. We provide material certificates, pressure test records and the commercial documents your customs broker requires.
Q: How is the deck protected in transit?
A: The deck and manifold faces are coated with anti-rust oil, foam supported and packed in a timber case marked to ISPM 15, with packing photos sent before dispatch.
Middle East and Gulf
Q: Will the head survive hot climate duty?
A: Yes, with a healthy cooling system. On machines working above 45 C we recommend checking the radiator core, thermostat and coolant concentration at the same time as the head repair.
Q: Do you accept L/C for workshop orders?
A: Yes, T/T and L/C are accepted, and repeat buyers can be supplied against a rolling schedule.
Southeast Asia
Q: How do you stop rust on the machined faces during sea freight?
A: Machined surfaces are oil coated, film wrapped and packed with moisture absorbent bags inside the case, which suits humid destinations.
Q: Can I combine a head with gaskets and injectors in one shipment?
A: Yes, and we recommend it, since the repair normally needs the gasket kit and injector washers at the same time.
South America
Q: Is the head suitable for high altitude operation?
A: The casting itself is not altitude sensitive. On high altitude machines the fuel setting and cooling performance matter more, so tell us the working altitude and we will note it for your fitting.
Africa
Q: Can our workshop fit it without a machine shop?
A: Yes, the assembly is ready to bolt on; the workshop only needs a torque wrench, a straight edge to check the block deck and the timing marks. We supply a written assembly note.
Q: Can you send a complete top end kit?
A: Yes, head, gasket kit, head bolts and injector washers can be packed as one top end kit.
Russia and CIS
Q: Are low temperature conditions a problem for the head?
A: Not for the casting. Cold start protection depends on coolant concentration and oil grade, which we mark on the packing note, and a block heater can be supplied if required.
Q: Which documents are provided for customs?
A: Commercial invoice, packing list, certificate of origin on request, and a technical description sheet with engine model, head type and weight for correct classification.
About Us
We focus on after-market hydraulic and powertrain maintenance parts for construction machinery, covering hydraulic pumps, travel motors, swing motors, control valves, gear pumps, gearboxes and diesel engine assemblies and components for excavators, mining dump trucks, skid steer loaders, rotary drilling rigs, pile drivers, concrete mixers, pump trucks, cranes and harvesters. Our workshop supplies both single-part repair orders and full overhaul kits.
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