A top-end rebuild is the most expensive routine job on a Kobelco engine, and the decision to start one is usually made on emotion: the engine smokes, so the head comes off. In practice three measurements decide whether a head job is needed, what it will include, and whether the block should come out at the same time. Doing those measurements first is the difference between a planned rebuild and an open-ended bill.
Measurement one: valve recession
Valve recession is how far each valve has sunk into its seat after thousands of hours of hammering. It is measured from the cylinder head face to the valve stem tip, or to the valve head face, depending on the engine manual. When recession passes the limit, the valve no longer closes cleanly, compression drops, and the seat has to be replaced rather than recut. This is the measurement that decides whether a head can be refreshed with a grind or needs new seats — and on the small D04FR and D06FR engines the seats are listed separately for exactly this reason: VA3430101600 for the exhaust valve seat, with VA3060431601 as the valve spring seat on the same family. Both are quoted by Guangzhou Shenyue Machinery Technology Co., Ltd. against the engine plate rather than the machine badge.
Measurement two: head flatness and cracks
A warped head will not seal, no matter how good the gasket is. Check flatness along the length and across the width with a straight edge and feeler gauge; check for cracks between the valve seats and around the injector bores, which is where thermal cracking starts. A crack test — magnetic particle or dye penetrant — is cheap next to the labour of assembling a cracked head and finding the leak at first start. If the head needs more than a light skim, the decision usually moves to a new or exchange head; on the J05E the bare head is quoted as VHS111981060, and a replacement is often the cheaper route once machining and downtime are counted.
Measurement three: the gasket story
The head gasket itself tells you what happened. A gasket that has failed between cylinders points to a warped head or stretched bolts. A gasket that has failed to a water passage points to a sealing problem or a cracked head. A gasket that is intact but the engine still loses coolant points somewhere else entirely — a cooler, a hose, or a liner. On the 6D34 the head gasket is quoted as VAME081734; on the J05E and J08E the number differs by engine variant, which is why a photograph of the old gasket, laid flat with the number visible, is the fastest way to get the right one.
Head bolts: the part everyone reuses
Torque-to-yield bolts stretch when they are tightened and do not spring back. Reusing them means less clamp load, which leads to gasket failure a few thousand hours later — usually just outside whatever warranty the workshop gave. On the J05E the head bolts are quoted as VHS111852450 and VHS111852460, and they are a replace-every-time item. Torque them in the manual's sequence, in stages, and use a calibrated wrench; a rattle gun and a guess is not a torque procedure.
What else goes in the basket
A head job is never just a head. Valve stem seals, injector seats and washers, coolant, oil and filter, thermostat, and the intake and exhaust gaskets all belong in the same order, because the machine is already down and each missing part adds days. On high-hour engines, look at the camshaft and followers while the head is off — a worn cam lobe is visible at that point and invisible afterwards. The bearing and lower-end side of the same decision is covered in our engine bearing sets guide, and the full cylinder-head and valve-train list sits under engine parts. Hino publishes the base engine data for the J-series on hino-global.com. Guangzhou Shenyue Machinery Technology Co., Ltd. can quote either route — a bare head or a complete assembled unit — so the comparison is made on delivered cost, not on the headline part price. A top-end rebuilt onto a worn bottom end is a job with a scheduled return.
Before you order
Send the engine plate, the machine serial number, the numbers from the old gasket and head, and the measurements you took. We will quote the head, the seats, the bolts and the gasket set as one list, with the grade of each item stated — genuine, OEM or aftermarket — so there is no surprise when the crate is opened. Guangzhou Shenyue Machinery Technology Co., Ltd. holds 3,000+ part types on the shelf and 100,000+ part numbers available to order through Kobelco, Hino and KPM channels, including the J05E and D04FR engine lines. Email kobelco-parts@foxmail.com or WhatsApp +86-18144825432.
We are an independent supplier of Kobelco parts and not an authorized Kobelco dealer. We are authorized distributors for Mitsubishi, Garrett, TONGMYUNG, Marusan and NIKURA.
Frequently Asked Questions
What is the cylinder head number for a Kobelco J05E engine?
Our stock records quote VHS111981060 as the complete cylinder head for the J05E, with VHS111852450 and VHS111852460 as the head bolts. Guangzhou Shenyue Machinery Technology Co., Ltd. confirms the variant against the engine plate, because J05E builds differ by emission market.
Can I reuse cylinder head bolts on a Kobelco engine?
No. Torque-to-yield head bolts stretch permanently during tightening, so a reused bolt delivers less clamp load and the new gasket fails early. Treat head bolts as a replace-every-time item and torque them in the manual sequence with a calibrated wrench.
What are the valve seat numbers for D04FR and D06FR engines?
The exhaust valve seat is quoted as VA3430101600 and the valve spring seat as VA3060431601 on our records for the D04FR and D06FR families. Both are confirmed by Guangzhou Shenyue Machinery Technology Co., Ltd. against the engine serial number before dispatch.
How do I know whether my head needs skimming or replacing?
Measure flatness with a straight edge and feeler gauge, and crack-test between the valve seats and injector bores. A light skim within the manual limit is acceptable; a head that is cracked or below minimum thickness should be replaced, and a bare J05E head is quoted as VHS111981060.