The bore and the spool valve as a pair
A valve bore is the machined passage in which a spool valve moves, opening and closing oil passages as it travels. The fit between the two is the precision of the valve body: the spool valve can only control oil accurately if the bore it moves in holds its shape. When the bore wears, that fit loosens, oil leaks past the valve, and pressure control suffers. The fault then appears as a valve function problem — a harsh shift, a delayed shift, slipping, or lock-up that cannot hold — even though the spool valve itself may be unchanged. Understanding the pair is the key to understanding bore repair: the repair must restore the bore, not merely clean the valve.
How a bore wears
Bores wear through use, contamination and pressure cycling over time. Contaminated oil carries debris through the bore, pressure cycles load the working surface repeatedly, and the spool valve itself moves against that surface repeatedly. Wear is usually gradual, which is why bore faults often appear as gradually worsening shift or pressure symptoms rather than as a sudden failure. A bore that has worn gradually should not be expected to recover by cleaning, because cleaning removes debris without restoring the worn surface.
Why polishing alone is not the repair
Polishing cleans and smooths a surface. It does not replace material that wear has removed, and it does not restore the fit between spool valve and bore. The company process documentation states the distinction directly: worn valve bores are repaired with a sleeve, not by polishing alone. A sleeve restores the working surface by fitting a new surface inside the worn bore, so that the spool valve once again moves in a bore of the right fit. A buyer who is offered polishing for a worn bore should ask directly whether a sleeve is the proposed repair, and should treat polishing-only as a different, lesser scope rather than as the same repair described differently.
Where sleeve repair sits in the sequence
Sleeve repair is one step inside the documented repair sequence, and its position matters. Defect screening comes first and removes worn, deformed, fatigued or out-of-tolerance core parts that should not proceed. Ultrasonic cleaning and wear-part replacement follow. Sleeve repair is then made where a bore is worn. Bench testing follows and verifies the result across oil flow, pressure stability, shift response and sealing. A sleeve fitted without screening may be fitted to a unit that should not have proceeded. A sleeve fitted without bench testing afterwards has not been verified. Ask whether the full sequence applies to the unit in question, not only whether a sleeve will be fitted.
Which bores, and how many
Not every bore in a valve body wears equally, and a repair scope should name the bores it covers. A repair inquiry should therefore ask which bores inspection found worn, and which of them are proposed for sleeve repair. A scope that says sleeves in general, without naming the bores, cannot be compared with another scope or verified afterwards. A scope that names the bores can be checked against inspection findings and against the bench result, because the bench test will show whether the functions those bores serve now hold pressure and respond correctly.
Sleeve repair and the rest of the valve body
A sleeve repair restores bores. It does not by itself renew solenoids, gaskets or sealing surfaces, and a complete repair scope should state whether those items are included. Solenoids are bench-tested as part of the sequence, gaskets belong to the wear scope to be agreed, and sealing surfaces are prepared where needed to reduce leak risk. A buyer comparing two repair offers should compare the whole scope — screening, cleaning, sleeve work, gaskets, and bench testing — rather than comparing the sleeve step alone, because an offer that omits the surrounding steps is not the same scope.
Sleeve repair or replacement
Sleeve repair recovers the existing valve body and suits damage that is limited and recoverable. Replacement starts from a different unit and suits wider damage, or a job where time matters more than recovering the existing unit. The choice should follow inspection findings: the bores found worn, the solenoids found faulty, and the gaskets and sealing surfaces found wanting. The valve body repair page and the valve body replacement page compare the two routes on the same terms, and the sleeve repair service page states the service scope itself.
What to ask before a repair is agreed
Ask which bores are worn and which are proposed for sleeve repair. Ask whether the full repair sequence applies, and whether bench testing afterwards covers oil flow, pressure stability, shift response and sealing.
Describe the valve body fault and any inspection findings you hold. Share the quantity and your target date, and ask for MOQ and lead time for your order. Confirm fitment details before ordering, and confirm packaging and warranty before ordering. Warranty is at least 1 year, and certificates are available upon request.
Documenting a sleeve repair
A sleeve repair should leave a record that a later reader can verify, because the repair itself is hidden inside the valve body once reassembled. The record should name the bores found worn and the bores fitted with sleeves, state whether the full repair sequence applied — screening, cleaning, wear-part replacement, sleeve work, and bench testing — and report the bench result check by check across oil flow, pressure stability, shift response and sealing. It should also state whether gaskets and sealing surface preparation were included in the scope. A repair without that record cannot be compared with another repair offer, cannot be verified after fitting, and cannot support a warranty discussion, because none of the parties can say what was actually done.
Sleeve repair for repeat and wholesale buyers
A wholesale or distributor buyer considering sleeve-repaired valve bodies should apply the same documentation standard across every unit, not only to the first sample. The standard is: named bores, full sequence, bench result by check, and scope including gaskets and sealing. Units that meet the standard can be compared and reordered with confidence. Units that do not meet it should be treated as a different offering, even if they are described with the same words, because the words alone do not state the scope. A repeat order inquiry should cite the documentation standard explicitly, so that every unit in the order is prepared and reported to the same terms.
Common sleeve repair inquiry mistakes
The most common sleeve repair inquiry mistake is accepting polishing as a substitute for a sleeve without asking which bores are worn and what the proposed repair is for each. The second is agreeing a sleeve scope without asking whether bench testing follows the repair, so that the repair is never verified. The third is comparing two repair offers by price alone when their scopes differ — one including screening, cleaning, gaskets and bench testing, and the other including only the sleeve step. Avoid all three by asking for named bores, the full sequence, and the bench result by check, and by confirming fitment, packaging and warranty before ordering.