Below is a focused, step‑by‑step procedure for checking and correcting gear mesh/backlash (commonly called “gear adjustment” on gear‑driven timing trains) on a Perkins 3.152 engine. This covers measuring/backing out improper mesh, correcting end‑float/thrust using shims or new thrust washers, replacing worn gears, and changing gearsets if a net gear ratio change is required. Follow OEM service manual values where available — I give procedural steps and common tolerances/techniques but not every OEM torque or dimension (reference the Perkins manual for final values).

Tools & materials
- Full metric socket/ratchet set, extensions
- Torque wrench (capable of specified OEM torques)
- Gear puller / bearing puller set
- Dial indicator with magnetic base (0.01 mm / 0.001 in resolution)
- Feeler gauges
- Straight edge / small machinist’s square
- Soft mallet and drift punches
- Snap ring pliers (if applicable)
- Small pry bars
- Calipers or micrometer
- Clean rags, degreaser, parts tray
- Engine assembly lube
- New gaskets/seals (timing cover, crank seal) and RTV as required
- Replacement timing gears, idler gear, thrust washers, shims (as required)
- Anti‑seize / appropriate thread locker (as per manual)
- Personal protective equipment (gloves, eye protection)

Safety & prep
1. Work on a cool engine in a well‑ventilated, level area. Secure the vehicle/tractor with parking brake, chock wheels, and/or put under supports if removed.
2. Disconnect the negative battery terminal to prevent accidental cranking.
3. Drain engine oil if removal of the timing cover or gear housing will expose oil ways or you will remove gears that allow oil loss.
4. Wear PPE. Keep hands/loose clothing clear of rotating parts. If engine must be rotated later, use a breaker bar on the crank pulley only.

Overview of procedure
- Remove covers and ancillary parts to access timing gears.
- Inspect gears, bearings, thrust washers, and keyways for wear/damage.
- Measure gear backlash and end‑float with dial indicator.
- Adjust mesh by changing thrust shims/washers or moving idler/gear stops per design.
- Replace gears or washers where wear is excessive.
- Reassemble with correct torque, gasket/seal replacement, and re‑check backlash.

Step‑by‑step

A. Access and initial inspection
1. Remove fan, belts, any accessories blocking timing cover, then remove timing cover and any oil slinger/retainers to expose timing gears.
2. Clean the area thoroughly so measurements aren’t obscured by grime.
3. Visually inspect gear teeth for chipped, rounded, or pitted teeth; inspect keyways and bolt holes; check condition of gear bores and key pads. If any gear tooth wear or pitting exists, plan on replacement.
4. Inspect thrust washers (if fitted) for wear spots or metal loss. Replace if worn beyond ~0.1–0.2 mm or if you see scoring.

B. Marking and safe rotation
5. With a marker or scriber, mark gear timing positions relative to each other (timing marks). This ensures you can restore alignment if you must remove gears.
6. Rotate the engine by hand (use a socket on the crank bolt) to bring gears into a neutral mesh position for measurements. Never rotate with the starter while parts are loose.

C. Measuring gear backlash (radial/backlash between mating gears)
7. Mount the dial indicator so its plunger contacts the face of a gear tooth near the top of the tooth (not on the fillet). Magnetic base on engine block or another stable point.
8. Hold one gear fixed (prevent it from rotating) and gently rock the mating gear back and forth with light force, noting maximum indicator movement. That variation is gear backlash.
9. Compare measured backlash to the specification in the Perkins manual. Typical acceptable backlash for older diesel timing gears is in the small range (a few thousandths of an inch / 0.05–0.40 mm depending on design); consult manual. If backlash is excessive, gears or thrust clearances need correction.

How tool is used: The dial indicator translates small angular movement of a gear to a linear readout; set zero at one extreme and measure travel to the other. Ensure indicator is perpendicular to tooth face for accurate reading.

D. Measuring axial end‑float / thrust clearance
10. Place the dial indicator so the plunger bears on the front (or back) face of the gear and zero it. Gently push/pull the gear axially and record total end‑float.
11. Excessive end‑float means worn thrust washers or improper shim stack. Too little axial clearance (binding) can damage bearings/gear faces.

E. Correcting mesh / end‑float
Option 1 — Adjust shims or replace thrust washer(s)
12. If the design uses shims/thrust washers behind the gear: remove gear retaining bolt and gear (use puller if needed). Inspect the thrust washer thickness. Replace with new or correct thickness to obtain required axial clearance.
13. Reinstall gear with new shims/washers, torque fasteners to spec. Re‑measure backlash and end‑float. Iterate shim thickness until within spec.

Option 2 — Replace worn gears or replace idler to change ratio
14. If backlash is excessive due to gear wear, replace the worn driving or driven gear(s). If changing gear ratio intentionally, install a new gearset with the desired tooth count — note this typically requires matching gear pairs and may change timing — follow OEM methods for gear replacement and timing mark alignment.
15. When replacing, verify gear tooth pitch and hub/bore fit. Some gear changes require different idler or cam tower components — get correct parts.

Option 3 — Adjust idler position or use eccentric mounts (if equipped)
16. Some rigs use an adjustable idler or eccentric cam to set mesh. Loosen mounting bolts, rotate eccentric to obtain proper backlash per dial indicator, then torque bolts to spec. Recheck after torquing.

F. Reassembly and verification
17. Clean mating surfaces, replace timing cover gasket and any seals (crank seal, cover O‑rings) before reassembly.
18. Refit timing cover and accessories. Reconnect battery.
19. Rotate engine by hand at least two full revolutions to verify no interference and that timing marks realign. Re‑check backlash and end‑float after a few rotations.
20. Start engine and listen for abnormal gear whine or knocking. Re‑check after warm‑up if practical.

Common pitfalls & how to avoid them
- Relying on visual only: always measure backlash/end‑float with a dial indicator. Small errors cause noisy, short‑lived gear life.
- Incorrect timing marks/forgotten marks: always mark before gear removal and verify alignment during reassembly.
- Reusing worn thrust washers/shims: replace if any scoring, thickness loss, or distortion.
- Over‑tightening bolts: distorts gear seating and can alter backlash; always use specified torque and torque sequence.
- Ignoring keyways/woodruff keys: replace keys if damaged; a damaged key will cause timing jump.
- Not replacing seals/gaskets: oil leaks and contamination will accelerate wear.
- Attempting to change gear ratio without addressing mating parts: changing one gear tooth count often requires mating gear and possibly re‑calibrating governor or pump drive — get correct aftermarket or OEM kit.

Replacement parts commonly required
- Timing gear(s) (crank, cam, idler) if worn/damaged
- Thrust washers or shims
- Gear retaining bolts (often single‑use or torque‑to‑yield)
- Timing cover gasket and crank seal
- Woodruff keys / key stock
- Any worn bearings behind gear bores

Notes on intentional gear ratio changes
- On engines, “changing gear ratio” (e.g., for PTO speed) typically requires matched gear sets and careful recalculation of timing if the cam/crank relation changes. This is not a minor tweak — get a matched gear kit and the Perkins instructions. After changing ratio, verify engine timing and injection pump timing where applicable.

Final checks
- Verify oil pressure immediately after start and watch for leaks.
- Re‑inspect after initial run (first 50–100 miles/operating hours) for loosened fasteners or abnormal wear.

If you want exact Perkins 3.152 OEM specs (backlash, thrust clearance, gear torque), consult the Perkins service manual or I can list typical specification sources — but I did not include specific numeric specs here so you follow the correct factory figures.
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Perkins 3.152 After Cylinder Head Rebuild 3

Perkins 3.152 Keel Cooled Marine Diesel Engine Demo Run Of Used Perkins 3.152 Narrowboat Engine.

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Purpose: replace the spin‑on oil filter on a Perkins 3.152 and restore correct oil filtration and flow. Below are ordered steps with the engineering theory for each action and how the repair fixes the fault.

Preparations (why it matters)
- Theory: clean oil and correct oil pressure protect bearings and hydraulic clearances. A clogged/soaked filter increases restriction, may trigger low‑oil‑pressure or open the bypass valve so unfiltered oil circulates.
- Action: gather correct spare filter (Perkins‑specified type), correct grade/amount of engine oil (use Perkins recommended diesel oil, commonly 15W‑40 for many applications but confirm your manual), drain pan, filter wrench, rags, gloves, new drain‑plug washer, jack/stands if needed.

Step 1 — Warm engine briefly, then stop
- Theory: warm oil flows faster and carries suspended particles out of the filter; warming reduces viscosity so oil drains more completely.
- Action: run engine 3–5 minutes, shut off, engage parking brake. Wait a few minutes to avoid scalding.

Step 2 — Prepare access and protect area
- Theory: working space and containment prevents spills and allows safe removal.
- Action: level machine, place drain pan under oil sump and under filter location, remove engine top filler cap to vent.

Step 3 — Drain engine oil (recommended when changing filter)
- Theory: draining removes most contaminated oil and sediment that would bypass filter during removal. If only changing filter, some oil drains from filter housing anyway, but draining is cleaner and recommended periodically.
- Action: remove sump/drain plug, allow oil to drain completely into pan. Replace drain plug and washer when draining is complete (leave hand snug — final tighten after filter installed).

Step 4 — Remove the old oil filter
- Theory: the old element holds trapped particles, soot and degraded media; removing it clears the flow path so new element can do filtering.
- Action: use strap or cup filter wrench, loosen and remove filter. Expect some oil to spill—catch it. Inspect filter for metal particles or abnormal deposits (large metal flakes indicate more serious wear).

Step 5 — Clean filter mounting face and inspect
- Theory: a clean sealing surface ensures the new gasket seals properly; debris can cause leaks or allow unfiltered bypass.
- Action: wipe mounting flange and threads; ensure old gasket didn’t stick to engine. Remove remnants.

Step 6 — Prime and install the new filter
- Theory: pre‑filling the filter reduces dry start wear and eliminates trapped air; proper gasket contact prevents leaks.
- Action: smear a thin film of clean oil on the new gasket. Optionally pre‑fill spin‑on filter with oil (if the filter orientation allows). Thread filter onto mounting by hand until gasket contacts, then tighten to hand‑tight plus ~3/4 turn (or to the torque in Perkins manual). Do not over‑tighten.

Step 7 — Refit drain plug and refill with oil
- Theory: correct oil level and clean oil restore lubrication, hydrostatic pressure, and cooling.
- Action: ensure drain plug and washer are fitted and tightened to spec (snug if no torque spec available). Refill through filler neck with the correct oil to the recommended level. Replace filler cap.

Step 8 — Prime system and check for leaks
- Theory: cranking or brief run builds oil pressure, seating the filter gasket and circulating oil through new media; checking reveals leaks or pressure problems immediately.
- Action: start engine, idle a minute while monitoring oil pressure gauge (or warning light) and checking for leaks at filter and drain plug. If pressure is low or warning lights stay on, stop and investigate (could be incorrect filter, plugged suction, or other fault).

Step 9 — Shut down and re‑check oil level
- Theory: oil that filled the filter returns to sump; level changes slightly after run.
- Action: after a minute run and a short cool-down, check dipstick and top up to correct level.

Step 10 — Dispose of old oil and filter properly
- Theory: used oil and filters are hazardous waste and may contain contaminants; proper disposal prevents environmental harm.
- Action: place old filter in sealed container and take oil + filter to an authorized recycling facility.

How this repair fixes the fault (concise)
- Symptom: clogged filter or saturated filter media reduces oil flow and/or causes bypassing of filtration. Resulting low oil pressure can cause increased bearing wear, noise and eventual failure.
- Fix mechanics: replacing the filter removes the restriction and restores the intended flow path through fresh pleated media, so contaminants are trapped again. The new gasket prevents external leakage. Combined with fresh oil (if changed), particle load in the system drops and oil viscosity/film strength are restored, bringing oil pressure back to normal and re‑establishing protective lubrication film on bearings and moving parts.

Quick failure signs that indicate filter change wasn’t sufficient
- Persistent low oil pressure, metal particles in removed filter, or engine noises after change indicate deeper problems (bearing wear, blocked oil gallery, failed pump). Those require further diagnosis.

End.
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