FACTORY TOPOLOGY / FITTED ASSEMBLY UNVERIFIED

Identify the relief valve.
Keep its spring distinct.

The factory 1500 plate lists a piston, spring, copper sealing washer and long hex plug. This block-mounted assembly is separate from the oil pump and the spin-on filter. Its parts have not been identified or measured on this car.

A bench reference, awaiting fitted geometry

The main engine CAD does not yet contain this assembly. The separate four-part STEP uses an exploded bench layout with no engine coordinates. Two dimensions have documentary anchors below; every other size and profile is an estimate. The drawing and STEP explain component relationships, not tool access, installed spring compression or a removal path.

Download four-part bench STEP ↗Dimensions and source record ↗
38.8 mmSPRING FREE LENGTH · UK WORKSHOP REFERENCE

The manual also prints 1.53 inches. The STEP follows its metric value; the figures are rounded equivalents. This does not establish installed length, preload, rate or relief pressure on this car.

14 mm ID6K433 REPLACEMENT WASHER · SUPPLIER NOMINAL SIZE

The replacement listing identifies a copper crush washer. Its outside diameter, thickness and the fitted washer remain unmeasured.

Rotate the bench reference

Four separated parts, in millimeters. The gaps are display spacing; the parts stay in this bench layout while you inspect them.

Loading the four-part reference…

Four parts to keep identified

The illustrations are unscaled recognition diagrams. The factory plate MB0699, PDF page 61, printed 107-B85/B86 lists one of each at items 12–15.

ITEM 12 · 132107

Piston / plunger

The replacement photo shows a head and long stem. The bench shape follows that form; head diameter, stem size, length, surface condition and seat are unverified.

ITEM 13 · 131535

Relief spring

The bench spring has the UK manual's 38.8 mm free envelope. Coil count, wire diameter, winding direction, end treatment and spring rate are estimated or unmodeled. A matching free length alone cannot identify or calibrate a spring.

ITEM 14 · 6K433

Copper washer

The factory plate specifies one copper washer. The workshop page calls for renewal on refit. The bench ring's 14 mm opening is a replacement comparison; its outer size, section and compression are estimates.

ITEM 15 · 107246

Plug / valve body

The replacement photo shows a long hex body, threaded shank and opening. The STEP uses an unthreaded shank and a blind display bore. Hex size, thread, engagement, internal depth and tightening specification need fitted evidence.

What the owner photos leave hidden

IMG_6966, IMG_6967–6970 and IMG_6897 show the fitted filter/distributor side, but no relief body can be confidently identified in the reviewed views. There is no verified photo hotspot or engine placement for this assembly. These two views help plan the missing capture; they do not identify a hex head as the relief plug.

Blue PF53 filter beside the engine, with nearby cables and structure obscuring the block face
IMG_6966 · Filter-side overview. The blue PF53 identifies the fitted canister. It and the nearby wiring obscure the head/block area. A repeat view during an already-planned filter change, after the canister has been removed, would expose more of the mounting area; keep the filter head and surrounding connections in the frame.
Lower engine-side view with a large hose, cross-car tube and several visible fastener heads
IMG_6897 · Lower-side obstructions. The large hose and cross-car tube hide portions of the lower block face. Several other fastener heads are visible, but none establishes the relief body. An additional angle must show the candidate body's shoulder and its actual joint to the block.

For a useful fitted record, pair a whole-side view with a close side view that shows the positively identified body from block joint to outer end. Put a scale in the same plane and record the view direction and named nearby datums. A head-only close-up cannot establish the hidden axis, projection or available tool space.

What the workshop sequence establishes

Operation 12.60.56, PDF page 11, printed page 84 is headed Engine—U.K. Specification. Its component sequence is: remove the body from the block, discard the removed washer, withdraw the plunger, then remove the spring. Refit reverses that sequence with a new washer; the manual calls for a replacement spring when its free length does not agree with the data.

That source does not establish the fitted North American assembly, socket clearance, thread specification, tightening torque or pressure calibration here. Keep it as a reference until the actual parts and applicable instructions are confirmed. The exploded bench gaps are display spacing, not withdrawal distances.

Capture during planned access

  1. Use the photo gaps above to plan a whole-side view and a close side view of the positively identified relief body, showing its shoulder at the block and outer end with a scale. Distinguish it from the filter-head retaining bolt and pressure-gauge connection; do not identify an obscured hex by position alone.
  2. Record any markings, hex across flats, shoulder-to-end projection and mounting-face position relative to named nearby engine datums. These are the missing constraints for locating the assembly in the engine CAD.
  3. If removal is part of planned service, photograph the untouched arrangement and each part as recovered. Keep the piston, spring, washer and body identified together. Record the piston head diameter/thickness and stem diameter/length; the relaxed spring's overall free length, outside diameter, wire diameter, turns and ends; the removed washer's inside/outside diameters and thickness; and accessible body dimensions and thread identification.
  4. Keep installed, removed, relaxed and compressed readings separate. Record source photographs, units and measuring method. Do not derive installed compression or relief pressure from the free spring length or add bench estimates to the direct-measurement log.