Tools & consumables
- Engine hoist / stands, lift gear, jack stands, blocking
- Basic hand tools and metric sockets/boxes, torque wrench
- Feeler gauges, feeler blades
- Dial bore gauge (0–100 mm) + outside micrometer (for bore gauge calibration)
- Telescoping gauge (optional)
- Vernier caliper / micrometer (piston diameters)
- Straight edge / feeler (head/block deck check)
- Cylinder hone (flex-hone/brush or single-stone/ball hone) + appropriate abrasive stones/brushes
- Variable-speed drill (if using hand hone) or professional honing machine
- Clean-up brushes, lint-free cloths, solvent/degreaser, compressed air
- Engine assembly lube and clean engine oil
- New piston rings (correct size/or oversize if rebore), new cylinder head gasket, main/rod bearing overhaul kit if required
- Plastigage (if checking bearings)
- Magnetic pickup tray, drip pans, gloves, eye protection, dust mask/respirator
- Torque angle gauge, marker/paint pen for match-marking parts

Safety precautions
- Work on a stable, level surface; support engine/vehicle safely with stands. Use an engine hoist for heavy lift.
- Disconnect battery; drain coolant and fuel. Ventilate area when using solvents.
- Wear eye protection, gloves, and a dust mask/respirator while honing (aluminium/iron dust & abrasive particles).
- Keep hands and loose clothing away from rotating tools; secure hone to drill properly.
- Dispose of oily/solvent waste according to regulations.

Overview & decisions
- You are either deglazing/light-honing (restore crosshatch for ring seating) or rebore/honing to an oversize (if cylinders are scored, out-of-round or beyond wear limits). Light honing: minimal material removed to remove glaze and restore 30–45° crosshatch. Heavy correction: machine shop rebore to oversize and fit oversize pistons/rings.
- Always measure before and after. If bore wear/taper/out-of-round is beyond service limits, send to machine shop.

Step-by-step procedure

1) Strip engine to access bores
- Remove cylinder head(s) per Perkins workshop procedure; label and keep bolts/parts in order.
- Remove oil sump/pan, timing cover, front accessories as needed to drop pistons.
- Remove connecting rod caps and push pistons out of bores from the top (or remove pistons with rings off if you keep rods in place). Mark pistons & rods and keep each piston/rod paired and numbered for reassembly.

2) Inspect pistons and bores
- Clean piston skirts and measure piston diameter at about 25 mm down the skirt with micrometer. Record dimensions and compare to bore sizes.
- Use dial bore gauge to measure each cylinder at three heights (top, middle, bottom) in two orthogonal directions (0°/90°). Record bore diameters, calculate taper and out-of-round.
- Refer to Perkins specifications (service manual) for allowable wear/taper/out-of-round and oversize increments. If within limits for light hone (usually small), proceed. If not, plan rebore and new pistons/rings.

3) Decide hone type and prepare
- Light deglaze/hone: use a flex-hone (nylon brush with abrasive, “brush hone”) sized for bore and grit ~180–240 for diesel. This removes glaze and produces crosshatch without removing significant material.
- Correction hone (stone/ball): use a rigid hone or shop hone if you need to remove measurable material. This is more aggressive and should be used only to bring bore to standard/oversize within limits. For significant correction, machine re-bore is preferred.
- Always choose correct hone diameter: it should be slightly larger than bore so stones/brushes bear on the wall.

4) Prepare the bore and tool
- Clean bores with solvent; remove carbon & deposits with brass brush—avoid scratching. Protect crank and bearings from debris (cover crank journals).
- Fit hone to drill or use machine. For flex-hone, secure correctly to drill chuck. For stone hone, ensure stones are intact and secure.
- Use manufacturer’s recommended rpm. General rule: moderate speed; do not run drill at full speed for stone hones. (Follow hone manufacturer instructions.)

5) Hone technique (light deglaze with flex-hone)
- Lubricate bore and hone with clean engine oil or honing oil/solvent recommended by hone maker.
- Insert hone and expand to contact walls. Start drill at low speed, move hone up and down the full stroke smoothly and continuously. Count strokes and maintain steady speed and stroke rate.
- Typical: 10–20 full up/down strokes for a flex-hone is common for deglazing; do not dwell at ends. Keep hone rotating and moving — never let it sit in one spot.
- Maintain perpendicular alignment to bore; shaft wobble causes taper. Use guide bushings or jig if available.
- Clean thoroughly after honing (see step 7).

6) Hone technique (correction hone)
- If removing material, use a single-stone or ball hone with progressive grit sizes. Only remove small amounts per pass. Check bore with dial gauge frequently (every few passes).
- Move hone continuously; use consistent force and stroke length. Avoid stopping mid-stroke.
- When target diameter achieved (or to match oversize piston spec), finish with finer grit to establish crosshatch.

7) Clean thoroughly
- After honing, flush bores with solvent/degreaser and brush with a soft bristle/nylon brush to remove abrasive grit. Repeat several cycles.
- Use compressed air to blow out passages (hold ring of piston to prevent debris entering oil galleries). Ensure all abrasive particles are removed — they will ruin bearings.
- Clean and inspect piston grooves and pistons; new rings should be installed.

8) Measure post-hone
- Re-measure bore at the same three heights/directions to confirm final diameter, roundness, and crosshatch. Confirm within spec or correct oversize piston selection.
- Check piston-to-wall clearance: piston diameter vs. bore diameter at installation height. Confirm appropriate clearance per manual for ambient/operating conditions.

9) Rings and piston preparation
- Always install new piston rings after any honing or rebore. Rings must be correct size/oversize class.
- Fit rings to piston in the bore to set ring end-gap: place ring in bore/over piston, square the ring in the bore and measure ring gap with feeler gauge. File/trim only if necessary and per instructions — most modern rings are supplied to correct end-gap for given bore size.
- Stagger ring end gaps 120° apart when assembling (follow engine manual).

10) Reassembly
- Lightly oil cylinder walls and ring faces with assembly lube/engine oil.
- Compress rings using proper ring compressor, insert piston into bore, drive piston down with wooden hammer handle or soft mallet until the connecting rod seats on journal — keep piston orientation correct (markings to the front).
- Refit rod caps with clean bearings, torque to spec. Use plastigage if you suspect bearing wear to check clearances before final assembly.
- Rebuild engine: new head gasket, torque head and other fasteners to Perkins torque sequences and values. Replace any seals/gaskets disturbed.

11) Initial break-in
- Prime oiling system and turn engine over by hand and with starter until oil pressure is achieved before long cranking.
- First run: run engine at varying RPMs and loads per break-in procedure (typically moderate rpm, avoid long idle, vary speeds and loads over first 30–100 miles/hours); do not lug or over-rev. Check for oil pressure, leaks, and unusual noises.
- Change oil and filter after initial run-in period to remove any residual metal/abrasive particles.

Common pitfalls & how to avoid them
- Not measuring before/after: always measure; guessing causes wrong repairs.
- Over-honing/removing too much material: remove minimum required; if more than small amount is needed, rebore at machine shop and fit oversize pistons.
- Poor cleaning: abrasive grit left in engine destroys bearings. Clean meticulously.
- Wrong crosshatch angle or lack of crosshatch: rings won’t seat or oil control suffers. Aim for about 30–45° crosshatch.
- Using wrong grit/tool or too high drill speed: glazing, chatter, taper. Use recommended hone and controlled, steady speed.
- Dwell/stop in bore: creates high spots and taper. Keep continuous movement.
- Reusing old rings after hone/rebore: always replace rings whenever cylinder surface is altered.
- Mixing up pistons/rods: keep them matched and numbered.
- Not checking piston-to-wall clearance: leads to piston slap or seizure.

When a machine shop is necessary
- Deep scores, heavy taper, or out-of-round beyond service limits.
- Requirement to move to standard oversize piston (0.25 mm, 0.50 mm, etc.) — shop will rebore, hone to exact size and supply pistons/rings.
- You lack precision measuring tools or honed surface control — shop honing machines produce repeatable results.

Replacement parts typically required
- New piston rings (mandatory whenever honing/rebore)
- Possible oversize pistons and rings if rebore required
- Cylinder head gasket (always replace)
- Rod/main bearings only if wear/damage found (check with plastigage)
- Any seals or o-rings removed during disassembly

Final notes (concrete: Perkins 4.107/4.108/4.99)
- These are robust Perkins 4-cylinder diesel blocks; they respond well to careful light honing/deglazing. However, follow Perkins workshop torque settings and tolerances for bores, piston clearance and head torque. If you don’t have the official manual, get it — it lists bore sizes, service limits and torque specs essential for correct work.

Done.
rteeqp73

PERKINS DIESEL Generator Upgrade ENGINE GOVERNOR IMPROVEMENT Pt.4 In this video we replace the governor spring in the injection pump. Unfortunately this does not yield the performance I am after.

Perkins Engines - Heritage Videos News Reviews - 3rd Edition Originally recorded by the Perkins Photographic Department, this Cine Film was converted to a VHS tape approx. 20 years ago.

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Perkins 4.107 / 4.108 / 4.99 — Catalytic converter replacement
Tools, PPE & consumables
- PPE: safety glasses, nitrile or leather gloves, hearing protection, respirator if grinding or cutting rusty metal.
- Lifting: floor jack, 2+ jack stands, wheel chocks.
- Hand tools: ratchet, extensions, swivel, 3/8" & 1/2" socket sets (deep & standard), combination wrenches.
- Torque wrench (range to 100 N·m).
- Breaker bar (1/2" drive).
- Impact wrench (air or electric) — optional but helpful for seized bolts.
- Penetrating oil (PB Blaster or equivalent) and wire brush.
- Exhaust hanger pliers or long-nose pliers.
- Angle grinder with cutting disc OR reciprocating saw (metal blade) for cutting pipes/bolts if necessary.
- Hammer, cold chisel, punch.
- O2 sensor socket (if engine has lambda sensor).
- Gasket scraper / flap wheel.
- Exhaust clamps or bolts/stud kit, new flange gasket(s), replacement studs/bolts/nuts as needed.
- High-temp anti-seize for O2 sensor threads, high-temp exhaust sealant (if specified), stainless exhaust clamps or V-band clamps if used.
- Replacement catalytic converter (correct part for vehicle/engine & exhaust layout), replacement O2 sensor if required.
- Welding gear only if welding is required and you are competent (note: welding near a cat mat will damage it — avoid welding into the converter body).

Safety & preparatory steps
1. Work on a cold vehicle in a well-ventilated area. Exhaust components are very hot after running; allow to cool fully.
2. Disconnect negative battery terminal to prevent accidental electrical shorts and avoid O2 sensor heater powering.
3. Chock wheels, lift vehicle with jack and support with jack stands on solid points. Never rely on the jack alone.
4. Wear eye/hand protection. Use respirator when grinding/cutting to avoid inhaling rust/metal dust.
5. If welding, ensure flammables are clear and have a fire extinguisher on hand.

Step-by-step replacement
1. Inspect and plan
- Locate catalytic converter(s) in exhaust path. Identify adjacent flanges, hanger positions and O2 sensor(s).
- Confirm replacement part matches inlet/outlet diameters, flange pattern, and orientation.

2. Remove heat shields and disconnect O2 sensor(s)
- Remove any heat shields covering the cat (often small bolts/rivets). Keep hardware if reusable.
- Disconnect and remove O2 sensor with O2 sensor socket. Coat threads with anti-seize on the new sensor (avoid getting on sensor tip). Label wiring if needed.

3. Soak fasteners and free seized hardware
- Spray penetrating oil on flange bolts/studs, clamps and hangers. Let soak 10–20 minutes and reapply as needed.
- Use wire brush on exposed threads to remove rust and help penetration.

4. Support downstream exhaust
- Support the tailpipe/muffler downstream of the cat with a jack and wood block or a second stand to take weight off hangers and make removal easier.

5. Separate flanges or cut if necessary
- If flanges are bolted: remove nuts/bolts with impact or breaker bar. Use breaker bar with a slow steady pull to avoid rounding heads. If studs are seized, use penetrating oil and heat (propane torch) carefully — heat only the nut/stud, not the catalytic body.
- If welded or bolts won’t budge: measure and mark a cut line on the pipe a short distance from the flange (leave some material for a clamp weld or to slip over when fitting new cat). Use an angle grinder with cutoff wheel or recip saw to cut the pipe. Use steady controlled cuts; protect surrounding components and your hands.

How tools are used:
- Breaker bar: apply slow, steady force. Use a cheater pipe only if you understand increased force can snap bolts.
- Impact wrench: use short bursts to avoid rounding; if it rounds, back off and use a bolt extractor.
- Angle grinder: secure pipe, use two hands, cut slowly. Sparks need to be contained; protect fuel/brake lines and heat shields.
- Recip saw: better control in tight spaces; use metal-cutting blades.

6. Remove exhaust hangers and free old cat
- Use exhaust hanger pliers or pry with screwdrivers to remove rubber hangers from pegs.
- Remove the cat assembly. If stuck, use penetrating oil and wiggle; tapping with a rubber mallet can help.

7. Prepare mating surfaces
- Clean flange faces with gasket scraper and wire brush until rust and old gasket material removed.
- Inspect studs; replace damaged or severely corroded studs/bolts. If studs are frozen, cut them off and re-tap or install flange repair studs as needed.

8. Fit new cat
- Position new catalytic converter. If it uses gaskets, place new gasket(s) between mating flanges.
- Hand-thread bolts/nuts to align. Use anti-seize on bolt threads where appropriate (not on gasket faces).
- For clamp-style joints, slide the clamp over the pipe to the joint, align, and tighten.

9. Torque hardware
- Torque flange bolts to spec. If exact Perkins torque is not available, typical small exhaust flange bolts: 25–45 N·m (18–33 ft·lbs). Clamp bolts: 20–40 N·m. These are general guides — consult vehicle manual if possible.
- Tighten progressively and evenly to avoid leaks.

10. Reinstall O2 sensor and heat shields
- Reinstall O2 sensor(s) using anti-seize on threads (avoid contaminating sensor tip). Reconnect wiring.
- Refit heat shields and any other brackets.

11. Lower vehicle and leak/test
- Lower the supports, start engine and let idle. Inspect all joints for leaks (use light or feel for leaks while watching for hot parts).
- Road test and recheck for rattles, leaks and fitment.
- Clear fault codes if necessary and verify the engine runs correctly and O2 sensor readings are within expected behavior.

Replacement parts typically required
- Catalytic converter (correct OE or aftermarket unit for vehicle/exhaust)
- Exhaust flange gasket(s)
- New studs/bolts/nuts as required (stainless preferred)
- Exhaust clamps or V-band clamps (stainless recommended)
- New O2 sensor if old one is damaged or has contamina­tion codes
- Anti-seize compound and high-temp exhaust sealant as required

Common pitfalls & how to avoid them
- Seized bolts/studs: soak with penetrating oil well in advance; heat the nut (not the cat body) if needed; use impact or cut and replace studs rather than rounding heads.
- Cutting in the wrong place: mark carefully and leave enough pipe for clamping or welding. Measure twice, cut once.
- Damaging O2 sensor or wiring: unplug sensor before working and set aside; use correct O2 socket when removing/installing.
- Welding into the catalytic body: welding on the converter body can destroy internal substrate — if welding is necessary, weld on the pipe or flange, not the converter shell.
- Not replacing gaskets/clamps: always replace gaskets and use new clamps to avoid leaks.
- Over-torquing: can warp flanges or snap bolts; tighten evenly to spec.
- Exhaust droop or hangers stressed: support and check hanger positions; use new rubber hangers if old ones are cracked.
- Using wrong replacement part: ensure inlet/outlet diameters, pipe length and flange patterns match.

Diagnostics after replacement
- Scan for fault codes and clear if appropriate. If cat was replaced because of emissions code, ensure O2 sensor signals switch normally after warm-up.
- Monitor for poor performance or check-engine lamp — may indicate O2 sensor damage, incorrect sensor placement, or leak upstream.

Final notes
- If you are uncertain about welding or cutting near fuel/ brake lines or electronics, get professional help.
- Keep old hardware as references; replace anything that’s corroded beyond safe reuse.
- Consult the vehicle’s workshop manual for any model-specific torque figures and exhaust routing peculiarities.

Done.
rteeqp73