Getting the Engine Running — Diagnostic Startup Procedure

Goal: get the Nissan A15 running so it can be diagnosed, without putting anyone in the platform and without relying on any safety circuit that hasn’t been verified. This is a diagnostics-only procedure — see “Before this machine goes into service” at the end for what must be fully restored first.

Sourced from the actual factory Operators Safety and Maintenance Handbook plus the machine-specific findings in Research and Specs. Quoted manual text is marked as such.

0. The key idea: use GROUND CONTROLS only, nobody in the platform

The handbook documents that this machine can be started and run entirely from the ground controls station — this is the normal, correct way to do maintenance work, not a workaround:

“If the engine is not running, operate the ground controls as follows: 1. If possible, inform platform occupant(s) of your intent to use the ground controls. 2. Position and hold the PLATFORM CONTROLS/GROUND CONTROLS selector switch to GROUND CONTROLS. 3. Start the engine using the ground controls IGNITION switch.”

Ground controls are on the left side of the machine. For all of this procedure:

• Nobody in the platform basket. No fall protection needed if nobody’s up there.
• No boom movement until the boom-position limit switches and the throttle solenoid are confirmed working (see §4). Chock the wheels; set the turntable lock pin.
• Keep the FUEL SELECT switch (bottom right of ground controls — only relevant if this unit turns out to be the dual-fuel-optioned A15, see My Story) in the gasoline position unless LP-gas is specifically confirmed connected and safe.

1. Before touching the key — mechanical prep

1. The engine was seized, and the crankcase was flooded. No. 2 was full of rainwater through its open plug hole (22 Aug), and draining the sump produced a gallon or more of water (23 Aug), against a sump that only holds 3.2 L of oil. It isn’t a hydrolock; with the plug holes open nothing can lock. This is rust, and because the bottom end has stood in water, rusted bearing journals rank alongside ring rust as the likely cause. Update 07 Sep 2026. After further soak, the crank now turns a full revolution by hand via a pry bar on the flywheel ring gear through the starter opening. Method in §1a below, which is exactly how it was freed. That doesn’t clear the rusted-bearing-journal concern on its own (§1a steps 8 and 9 are still worth doing before trusting the bottom end), and the starter shouldn’t be used to motor it until a no-spark cranking pass and compression check confirm it turns freely under starter torque, not just under a bar. Update 09 Sep 2026. That pass was done. The engine turns on the starter and has compression on all four cylinders (roughly 120, 120, 250, 250, 250, 90 and 185 psi across seven gauge readings, against a 181 psi factory standard and a 142 psi minimum; the three near 250 are above what this engine can make and point at liquid still in the bore or a gauge not bled between cylinders, while 185 and a repeat 180 sit at the standard). The oil still looked clean afterwards. Next mechanical step is the wet-versus-dry compression retest on Specs, which separates stuck or unseated valves from worn rings, with the reading written down against each cylinder number this time.
2. Spark plugs: which plug this head takes is unresolved, see Specs under “Superseded parts” and the plug seat warning. The factory part is NGK B4ES → now BR4ES, stock 1097, a 19 mm gasket-seat plug; the engine has AC Delco R44T, a 0.431 in taper. Reinstall the R44T only for cranking, gapped to the confirmed factory spec of 0.031–0.035 in (0.8–0.9 mm) — from the Nissan manual’s Service Data page, p.MA-9. Torque to 11–14 ft-lb (15–20 N·m), also from p.MA-9 — don’t just snug them by feel on an aluminum head. If the plug wires are off, don’t guess the routing — see Firing Order & Plug Wires for finding the No. 1 cap tower and walking the cap counter-clockwise 1-3-4-2. Wiring it the wrong way round the cap gives an engine that backfires and won’t start, easily misdiagnosed as a fuel problem. The distributor is electronic — there are no points to set; ignore point-gap and dwell figures, and don’t buy a contact set. The cap was inspected and is serviceable.
3. Throttle/choke solenoid (My Story, Grove P/N 7750000085): confirmed missing from its housing. This does not need to be reinstalled just to get the engine idling — its documented job is pulling the governor linkage to raise RPM under boom-function load (“rabbit mode”), not idle/basic running. Leave the governor linkage in its normal spring-returned position for first start. Do reinstall it before testing any boom function under load, and definitely before returning to service.
4. The disconnected coil — identified as the propane regulator/lock-off (22 Aug 2026). It is on the LP line, not the hydraulic manifold, which also confirms this machine carries the factory dual-fuel option. Leave it disconnected for the initial start and run on gasoline only — the LP side isn’t needed to idle the engine, and a half-connected LP circuit is a fuel-leak risk rather than an inert coil. Keep the FUEL SELECT switch at the ground controls in the gasoline position. Before ever energising the LP side, treat it as a full fuel system: pressure-test it, check the regulator and lock-off, and inspect every LP hose — the damaged hose noted in this area matters directly if it turns out to be an LP line.
5. Damaged hose near the coil: inspect before starting. If it’s a fuel or hydraulic line and it’s compromised, replace it before running the engine — don’t run a damaged fuel/hydraulic hose to “just see if it starts.”
6. Damaged limit switch wiring near the engine bay linkage (My Story): it’s for the boom lowered limit switch (P/N 7872001401, harness P/N 6512001903), mounted at the rear of the turntable under the boom base. Trace the damaged wire back to its connector and replace that harness section rather than splice it — this is a safety circuit, repair it properly before relying on it.

1a. Freeing a stuck engine — method

Written when the engine showed zero movement and a gallon of water had come out of the crankcase. That combination argued for opening it up early rather than escalating force against an assembly you can’t see. Sequence below reflects that.

Update 07 Sep 2026. This worked. Steps 3, 5 and 6 below (pull the starter, lever the flywheel ring gear through the starter opening rather than the crank pulley bolt, and rock it instead of heaving on it) freed the crank to a full 360° by hand after roughly two weeks of soak. It stuck partway, was backed off and retried, and came free, matching the rust-bond-breaks-on-the-reversal behavior step 6 describes. Steps 8 and 9 (drop the pan, pull a rod cap) are still worth doing before trusting the bottom end, but they’re no longer the only way forward.

Isolate first — prove it’s actually the engine

1. Take the drive belt off. A seized water pump or alternator feels exactly like a seized engine when you’re leaning on the crank bolt. With the belt off, spin each accessory by hand. Belt tension spec for refitting: 8–12 mm deflection under 22 lb (Specs).
2. Uncouple the hydraulic pump. No longer necessary (23 Aug 2026). This existed to rule out a seized pump before blaming the engine. A gallon of water out of the crankcase means the engine no longer needs ruling in. Leave the pump bolted on.
3. Check nothing is fouling the flywheel — a jammed starter pinion will lock a crank solid. Pull the starter and look at the ring gear.

Try gentle force, once

4. Bar it at the crank pulley bolt — 1-1/16 in socket, long breaker bar, not a ratchet. Prefer clockwise (normal running direction, viewed from the front), which is also the tightening direction for the pulley bolt. Counter-clockwise works against the bolt, so keep that force moderate and re-check the bolt afterwards.
5. Or lever on the flywheel ring gear, through the starter opening with a long pry bar. More mechanical advantage than the crank bolt, load spread through the ring gear rather than one fastener, and you can watch directly for movement.
6. Rock it, don’t heave on it. Small torque one way, small back, repeated. Rust bonds break on the reversal, not on one long push. Watch for any give at all — two or three degrees of elasticity means it’s a rust bond and it will come. Dead solid with no elasticity at all means stop pushing and open it up.

Why not impact

7. Don’t reach for an impact wrench on a dead-solid engine. Impact does break rust bonds, and on a mildly stuck engine it’s a normal move — but the torque path runs crank → rod → piston → ring, and the weakest link in that chain is a cast-iron ring that is currently rust-welded to the bore. Snapping one is a real outcome, and a broken ring fragment then scores the bore on the way out, which turns a rering into a rebore. Upstream you’re also risking the woodruff key, the timing sprocket and the crank nose — failures that cost you parts without moving the engine.

   The same objection applies in milder form to hammering pistons through the plug holes. It’s more controlled than impact torque, but it’s still blind force against a bond you can’t see.

   Both of those objections disappear once the pan is off — see below.

Open it up — this is the higher-yield path here

8. Drop the pan. It costs a gasket and an afternoon, and it converts guessing into looking. With the pan off you can see whether the bearing shells are rusted to the journals, whether there’s rust scale in the sump, and what condition the bottom end is actually in. It also gets penetrant onto the journals by hand — which is something no amount of fluid down a plug hole will ever do.
9. Unbolt the rod caps. This is the step that makes everything else safe. With the rods disconnected:
   • Test the crank on its own. If it turns freely with no pistons attached, the mains are fine and the problem is entirely in the bores. If it still won’t move, it’s the mains, and you know that for certain instead of inferring it.
   • Free each piston individually, pushing it up and out of its bore with a wooden dowel. One piston at a time, direct force in the right direction, nothing fighting you, and you can feel and see exactly what’s happening. No risk of loading a ring through the whole rotating assembly.
   • Rod cap nuts torque to 23–27 ft-lb going back together (Specs). Keep caps with their own rods and in their original orientation.
10. Pull the head if the bores are the holdup. No. 2 stood full of rainwater, so its bore has to be assessed anyway. Head bolts torque to 51–54 ft-lb on the factory sequence going back together (Specs).

Meanwhile — keep it soaking

11. Soak repeatedly over weeks, not once. Highest-leverage step on this list, and it beats any argument about which fluid to use.

    On fluid choice, honestly: the often-quoted ranking that puts a 50/50 ATF/acetone mix well ahead of PB Blaster comes from a single Machinist’s Workshop magazine test on rusted threaded fasteners, not stuck piston rings, and the numbers drift between retellings. Treat it as suggestive, not established. PB Blaster is a perfectly good penetrant — three weeks of it beats two days of anything. Kroil is the traditional choice if you want to buy reputation. Diesel is cheap enough to fill four bores generously and keep filling them, which is worth more than a marginal per-drop advantage.

    If you use acetone: it attacks some paint and plastics, it’s flammable, and the mix separates so it needs shaking. Keep ignition sources away.

12. Keep the bores topped up, and cover them. Acetone is gone from an open plug hole in a day in warm weather, leaving plain ATF behind. Rag in each hole or tape over them between visits.

13. Skip overfilling the crankcase. The idea is sound — it’s the only way to get penetrant to the journals without opening it — but it takes several times the 3.2 L the sump holds, acetone swells the crank seals, the thinned mix weeps from every gasket, and a crankcase venting acetone vapour through the breather is a serious fire hazard. Dropping the pan gets the fluid to the same surfaces, with less mess and more information.

14. Take the rocker cover off and back off the valve adjusters (or lift the rocker shaft — 4 bolts, 14–18 ft-lb to refit). Removes valve spring pressure from the equation, so you learn whether resistance is in the bores or the valvetrain, and lets you oil the valve stems. Valves stuck in their guides after sitting are common. Reset clearance to 0.35 mm hot afterwards (Specs).

Once it turns

15. Turn it through many full revolutions by hand with penetrant still in the bores, then mop them out and squirt clean engine oil into each bore before it runs.
16. Expect No. 2 to be the worst bore — it’s the one that stood full of rainwater. If it frees up everywhere but binds at one point in the rotation, that’s where to look.
17. Only after it spins freely by hand does anything below apply.

Set expectations honestly. A gallon of water out of the crankcase plus zero crank movement more often ends in a teardown than a free-it-and-run-it. That’s not a reason to stop soaking — it costs almost nothing — but the pan coming off should be treated as part of the plan, not a last resort.

2. Fluids and basics

• Engine oil: confirm level and smell before first start.
• Coolant: confirm level and smell before first start.
• Check both again per the handbook’s PRE-STARTING CHECKS section — check oil either before starting or 5+ minutes after a stop, for an accurate dipstick reading.

2a. Blocking item added 09 Sep 2026, the broken line at the oil filter head

A small-bore rigid line at the oil filter head is broken, both ends free. Its function is not yet identified. Identify it and then blank or repair it before the engine is asked to make oil pressure. If it is fed from the oil gallery it pumps oil out of the break the moment pressure comes up, on a bottom end that stood in water. This is a pre-start item, not a tidy-up-later item.

3. Battery and ignition

1. Check battery state-of-charge; clean/tighten cable clamps if corroded (per handbook PRE-STARTING CHECKS — this is a named daily check item, worth doing carefully given the machine sat).

2. Confirm the main power disconnect (if equipped) and E-STOP switches are in a known state. Specifically, the platform EMERGENCY STOP must be pulled out. The operator’s handbook says pushing it in removes all electrical power from the controls and stops the engine, and that it must be pulled out before resuming starting operation. Its warning on exactly this activity is explicit, “WHEN TESTING FUNCTIONS AND MONITORING THE RELAY BOARD IN THE GROUND CONTROLS, THE EMERGENCY STOP SWITCH IN THE PLATFORM CONTROLS MUST BE PULLED OUT AND THE KEY-OPERATED IGNITION SWITCH IN THE GROUND CONTROLS MUST BE” on. This is also what the previous owner’s marker writing on the ground control panel means, read in full on 09 Sep 2026. Also check the separate key-lock BATTERY DISCONNECT / EMERGENCY STOP.

3. With ignition ON but before attempting a start, verify there’s no continuous fuel pump / ignition-on chatter that would suggest a short from the rodent damage — a quick visual and smell check (melted insulation, burning smell) before applying power is worthwhile given the known damage.

The known no-spark fault, as of 09 Sep 2026

The engine cranks and will not fire. The ignition coil’s secondary is open circuit, which is a complete and sufficient explanation on its own. Before a start attempt.

1. Fit a new external-resistor coil. The one that came off is stamped “12V EXTERNAL RESISTOR REQUIRED”, and this circuit is designed around a dropping resistor that is bypassed during cranking. An internally-resisted coil behind that resistor gives a weak, heat-sensitive spark. See Specs under “Note on the ignition coil”
2. Find the dropping resistor and its cranking bypass, and check both. Neither has been located on this machine yet
3. Measure 12 V at the coil feed with the key on, with and without the ground-control selector held, so a feed fault is not left hiding behind the coil
4. Cap, rotor and leads. Order against the distributor’s own numbers, T4T56371 / 22100-G5110, not against a vehicle application. A cap bought on an application lookup did not fit. See Firing Order & Plug Wires
5. Lead routing is already worked out. No. 1 is the cap tower facing the rear of the vehicle, established by Method A on 09 Sep 2026, and the leads walk counterclockwise 1-3-4-2 from there. Recorded on Firing Order & Plug Wires

The ground-control selector reads as control power only, not ignition, from the machine’s own lower-control placard and the handbook’s description of it. Treat that as well supported rather than proven. The engine cranking on the key alone does not confirm it, because with an open coil there is no spark whichever way the selector is held, so step 3 above is what actually settles it.

4. First start attempt

Per the handbook’s general starting procedure (applies to gasoline; dual-fuel/diesel-specific notes are called out separately in the source and aren’t relevant to a gasoline-only start):

1. Position the PLATFORM CONTROLS/GROUND CONTROLS selector to GROUND CONTROLS (hold it there).
2. Turn the keyed IGNITION switch at ground controls to ON.
3. Turn that same keyed IGNITION switch to START. It is spring returned to ON. There is no START push-button at the ground controls. The operator’s handbook puts the push-button START on the platform controls, and the ground panel photographed on 09 Sep 2026 shows OFF / ON / START around the key. An earlier revision of this page said to push a START switch at the ground controls; that was wrong, and it matters here because §0 requires nobody in the platform.
4. Crank no more than 10 seconds per attempt. If it doesn’t start, let the starter cool ~2 minutes before trying again. If it doesn’t start after 4 attempts, stop and diagnose — don’t keep cranking.
5. Per the shutdown procedure in reverse — once running, let it idle; per the handbook, gasoline engines should idle 30 seconds before shutdown to avoid a backfire, so don’t kill it instantly once it catches.

5. Once it’s running

• Watch/listen for anything from the area of the damaged hose and the disconnected coil — with the engine running (and hydraulic pump therefore turning), any hydraulic leak at that damaged hose will show up now.
• Check oil pressure (gauge or light, whichever this unit has) comes up immediately.
• Let it idle and get to operating temperature before doing anything else. Do not attempt any boom or drive function yet — the throttle solenoid isn’t reinstalled and the mystery coil/limit switch aren’t resolved.
• Once satisfied it runs cleanly at idle, shut down per §4 step 5 and move to reinstalling/ diagnosing the remaining items before ever testing a function.

Before this machine goes into service (not just diagnostics)

All of the following must be fully repaired and verified — not bypassed, not left “good enough” — before anyone rides the platform or the machine drives/lifts under normal operation. Restated from My Story:

• Throttle/choke solenoid (P/N 7750000085) reinstalled and wired correctly, verified to actually raise RPM under load.
• Mystery coil on the hydraulic line identified, and either properly reconnected (if it’s a needed function) or properly and permanently removed/blanked off (if it’s genuinely not applicable to this unit’s fuel configuration) — not just left dangling.
• Damaged hose near that coil replaced.
• The damaged limit-switch wiring near the engine bay fully repaired (harness section replaced, not spliced — see My Story) and the switch’s actual function verified once identified.
• Boom retracted and boom lowered limit switches (rear of boom base / turntable) verified to correctly cut out high-speed drive when the boom isn’t stowed — this is a safety interlock, confirmed working, not assumed.
• Control bucket (platform controls) damage assessed and repaired.
• Tilt alarm tested (per handbook: press down on one corner of the tilt sensor on the platform frame; buzzer should sound).
• Full function cycle test from ground controls, engine running, before anyone ever rides the platform for the first time.