KA24DE: Engine Basics and Specs
The KA24DE is a 2.4L inline four-cylinder engine that uses an iron cylinder block with an aluminum cylinder head. Part of the reason Nissan used an iron cylinder block was to save money. The engine was intended for use in light trucks and SUVs, so weight saving wasn’t a significant concern. Early versions of this engine used a SOHC design with three valves per cylinder. Even with its relatively large displacement, the KA24 did not implement balance shafts.

Later versions of this engine used a DOHC design with four valves per cylinder which increased power and efficiency. Oddly enough, Nissan decided to use a shim-over-bucket configuration for the valve train instead of rocker arms. The KA24 uses a Hitachi sequential electronic fuel injection system. Nissan configured some KA24 engines for front wheel drive vehicles.

Production Run: 1988 – 2004
Displacement: 2389cc
Cylinder Block Material: Cast Iron
Cylinder Head Material: Cast Aluminum
Valvetrain: SOHC | Three Valves per Cylinder (1988 – 1997) – DOHC | Four Valves per Cylinder (1991 – 2004)
Stroke: 96mm
Bore: 89mm
Compression Ratio: 8.6:1 to 9.5:1
Horsepower: 134hp to 155hp
Torque: 152 lb-ft to 160 lb-ft
Deck: Open Deck
Configuration: Inline Four Cylinder
Cars That Came With the KA24DE
Nissan put the KA24E and KA24DE in a variety of different products through their life cycles. Some engines were destined for light duty pickup trucks and SUVs such as the Nissan Hardbody or Nissan Xterra, but the KA24 is best known for its appearance in the 240SX. It makes sense just to adapt the engine for multiple platforms rather than creating an all-new engine.

1989 – 1990: Nissan 240 (KA24E)
1990 – 1997: Nissan Hardbody (KA24E)
1990 – 1995: Nissan Pathfinder (KA24E)
1989 – 1995: Nissan Access / Nissan Prairie (KA24E)
1990 – 1992: Nissan Stanza (KA24E)
1989 – 1992: Nissan Pintara / Ford Corsair (KA24E)
1993 – 1996: Nissan Terrano II (KA24E)
2000 – 2004: Nissan Xterra (KA24DE)
1998 – 2008: Nissan Frontier (KA24DE)
1991 – 1998: Nissan 240SX (KA24DE)
1997 – 2000: Nissan R’nessa (KA24DE)
1998 – 2001: Nissan Presage (KA24DE)
1999 – 2001: Nissan Bassara (KA24DE)
1993 – 1997: Nissan Bluebird (KA24DE)
1993 – 2001: Nissan Altima (KA24DE-a)
KA24DE: Known Problems
Just like any other engine, the KA24DE has a couple of known issues that are common. The distributor is known for failing on earlier versions of the KA24. Another prevalent issue is a rattling timing chain, which occurs when the timing chain gets loose from age and begins to rub against the timing chain cover.

Supposedly the alternator fails more than many other vehicles, but we are not able to verify this problem. The last issue is the valve cover gasket which is known for leaking, which is mostly due to the bolt pattern and design of the valve cover. It’s a pretty quick and easy fix, but it is a common occurrence.

KA24DE: Tuning Potential
Thanks to the massive explosion of drifting, the 240SX has become the most popular tuner car in the world. Although many people upgrade to the SR20DET engine, many stay with the KA24DE because of its larger displacement. A naturally aspirated built can reach up to 200whp (230bhp), but it isn’t cheap. This kind of build requires full bolt-on, ported and polished head, bigger cams, and possibly a higher compression ratio.

Many people prefer the turbocharged route as it’s relatively cheap and makes pretty decent amounts of power. Although many people use an eBay turbocharger or the SR20 turbo, the better option is to use a quality turbo. Something like a Garrett GTX2867R would easily make 400whp or more. If you want excellent throttle response and lot’s of low-end torque, a Borg Warner EFR turbo would be a great solution. Unfortunately, the stock bottom-end isn’t strong and can only hold up to about 350whp. If you’re looking to go for big power, you’ll need a forged rotating assembly. If you end up dumping that much money into a KA24, you might as well swap in a 1JZ/2JZ or RB engine which will make way more power while also being more reliable.

Ka24E vs KA24DE
There seems to be quite a lot of confusion about the differences between the KA24E and the KA24DE. As you may expect, these engines are very similar, but there are a few fundamental differences that separate these engines. The most significant difference is the cylinder head.

The Ka24E was a single overhead cam engine with just three valves per cylinder, and the KA24DE was a dual overhead cam engine with four valves per cylinder. If you didn’t already know, the biggest power gains of any engine are found in the cylinder head. It was mostly the trucks that use the KA24E, but the 89-90 240SX also used it. Luckily, the 1991 – 1998 240SX used the KA24DE.

Design improvements of the dual cam engine include the use of a knock sensor, larger diameter girdled main bearings in the Japanese block, different oil pan, different oil pickup, dipstick location, and piston oil squirters.

1) Quick theoretical overview (what the part does)
- The oil pressure sensor (sending unit or switch) converts engine oil pressure into an electrical signal for the engine control unit and/or dashboard gauge/warning lamp.
- Switch type: closes or opens a circuit at a set pressure to drive a warning lamp.
- Sending unit (variable): a pressure-actuated variable resistor or piezo element produces a voltage/resistance proportional to oil pressure for the gauge/ECU.
- Failures: internal element failure (open/short/change in output), connector/wiring corrosion, or a sealing/thread leak. Symptoms from sensor failure are incorrect gauge readings, flickering/constant oil-pressure warning light, or stored fault codes — while an actual low-oil-pressure condition (worn pump, bearings, low oil) produces true low pressure and must be distinguished.
- How replacement fixes it: replacing a faulty sensor restores the expected electrical characteristic (correct resistance/voltage or switching behavior) and proper sealing. That returns accurate information to gauge/ECU and stops false warnings. If the underlying mechanical oil pressure is low, the sensor only reports it — replacing the sensor does not fix pump/bearing problems.

2) Ordered diagnostic + repair procedure (theory tied to each action)
1. Safety and preparation
- Theory: avoid electrical short, burns, and uncontrolled oil loss.
- Actions: Park on level ground, engine OFF and cooled. Disconnect negative battery terminal. Raise and support vehicle safely if required to access the sensor. Have rags and a small drain container ready for a little oil.

2. Confirm symptom and isolate electrical vs mechanical
- Theory: prevent swapping in a part when the real fault is oil pressure.
- Actions: read stored codes (OBD) for oil-pressure/sender faults. Observe gauge/warning behavior. If possible, back up with a simple bench test: with connector off, measure sender wiring resistance/voltage per a manual or use a multimeter to see if wire behaves like open/short. If you have a known-good sensor or can bench-test the suspect unit, that helps.

3. Locate the sensor
- Theory: sender threads into the oil gallery; removing it opens a passage but only a small volume.
- Actions: on the KA24DE the oil pressure sensor/switch is threaded into the engine block/oil filter housing area at the front/right side of the engine (adjacent to the oil filter / lower block area). Remove obstructing components (airbox, battery, covers) as needed to get a clear path.

4. Remove electrical connector and inspect wiring
- Theory: many “bad sensor” faults are connector corrosion or broken wires.
- Actions: unplug the connector, inspect for corroded pins, damaged wires, or melted plastic. Clean contacts with contact cleaner or replace pigtail if damaged.

5. Remove the sensor
- Theory: unscrewing the sensor relieves a sealed oil port; expect small oil seepage.
- Actions: place a rag/drip pan under the sensor. Use the correct deep socket or appropriate wrench to unscrew the sender. Keep orientation to avoid tearing the harness. Note whether the sensor uses an O-ring, crush washer, or tapered thread.

6. Inspect threads and port
- Theory: damaged threads or a missing/bad sealing element cause leaks.
- Actions: clean the port threads and check for metal chips or damaged sealing surfaces. Replace or repair as needed.

7. Prepare replacement sensor
- Theory: correct sealing method and correct part restore both electrical and hydraulic integrity.
- Actions: use OEM or equivalent sensor that uses the same sealing method (O‑ring, crush washer, or tapered thread). Do not over-apply Teflon tape to an O‑ring type. If the new sensor requires thread sealant per the manufacturer, apply the specified sealant sparingly.

8. Install new sensor
- Theory: proper torque compresses the seal without damaging sensor body or threads; correct electrical contact restores signal.
- Actions: thread sensor in by hand to avoid cross-threading. Tighten to the factory torque specification (consult the KA24DE service manual). If a torque value is not immediately available, tighten firmly with the wrench but avoid overtightening — using a torque wrench is recommended. Reconnect electrical connector, ensuring a snug, corrosion-free connection.

9. Reconnect battery and test
- Theory: verify no leaks and that the electrical signal corresponds to actual pressure.
- Actions: reconnect negative battery. Start engine and immediately check for oil leaks around the sensor. Observe the dash gauge/warning lamp behavior. The warning lamp should extinguish and the gauge should behave normally if the sensor was the fault.

10. Verify actual oil pressure (confirmation step)
- Theory: a new sensor can only report; confirm oil pressure mechanically if any doubt remains that the engine had low pressure.
- Actions: for definitive verification, fit a mechanical oil pressure gauge to the sensor port (or use an adapter) and measure pressure at idle and at higher engine speed. Compare readings to manufacturer specs. Typical expectations: pressure rises with rpm; consult the service manual for KA24DE numbers. If mechanical gauge shows acceptable pressure and dash/gauge now behave normally, the sensor replacement fixed the electrical/reporting fault. If mechanical gauge shows low pressure, further mechanical diagnosis (pump, relief valve, bearings, oil level/viscosity) is required — sensor replacement did not fix that.

3) Why each step matters (short)
- Disconnect battery: prevents shorts when unplugging connectors.
- Inspect wiring first: eliminates unnecessary part replacement.
- Use correct seal and torque: prevents oil leaks and sensor damage which would recreate the fault.
- Mechanical gauge verification: differentiates a replaced-but-still-reporting issue (electrical) from real low oil pressure (mechanical).

4) Typical failure signatures and what the repair actually fixes
- Symptom: intermittent or constant false low-pressure lamp or erratic gauge — usually a failed sender/switch (internals or connector). Replacing the sensor restores the correct electrical characteristic and solves false indications.
- Symptom: steady low-pressure reading confirmed by mechanical gauge — indicates actual low oil pressure; swapping the sensor will not fix the mechanical cause (oil pump, relief valve, bearings, oil level/viscosity).
- Symptom: oil leaking from sensor area — typically a bad seal or cross-thread; replacing sensor and correct sealing prevents the leak.

Done.
rteeqp73

Tools & supplies
- Transmission pressure gauge kit (mechanical gauge, hose, assortment of adapters including common Nissan/Sun/Schrader fittings). Gauge should read to at least 500 psi.
- Adapter or test port fitting that matches the transmission test port (don’t force wrong threads). Nissan uses several styles — Schrader-style or threaded boss; use factory-specified adapter when possible.
- Wrenches / ratchet set, torque wrench for reinstalling fittings.
- Jack and jackstands or vehicle lift (prefer lift if available).
- Catch pan, rags, gloves, safety glasses.
- Transmission fluid (correct type and quantity for topping off).
- New crush washer or O-ring and replacement pan gasket/filter if you remove pan.
- Mirror/flashlight, service manual or pressure spec sheet for your specific trans model.
- Optional: digital thermometer (for fluid temp), remote tachometer.

Safety precautions (non-negotiable)
- Work on a level surface. Chock wheels and use jackstands or a lift — never rely on a jack alone.
- Transmission must be warmed to normal operating temperature for meaningful readings (see steps). Hot fluid and components can scald — wear gloves and eye protection.
- Engine will be running while you’re under the car. Keep loose clothing, hair, and tools clear of belts, pulleys and moving parts.
- Use the parking brake and block wheels. If testing requires gear selection or throttle while stationary, keep a helper outside the vehicle ready to brake and hold.
- Dispose of drained fluid per local regulations.

High-level overview
1) Warm the transmission to operating temperature.
2) Locate the correct transmission pressure test port on the transmission/valve body.
3) Install the correct adapter/gauge and seal properly.
4) With engine running, read pressures in Park/Neutral and at specified RPMs and gear positions per the factory service manual.
5) Compare readings to factory specs, then remove gauge, reseal port, check fluid level and clean up.

Step-by-step procedure

1. Preparation
- Have the factory service manual or pressure spec sheets for the exact transmission model (the KA24DE is the engine — transmissions vary by vehicle and year; do not assume specs).
- Park vehicle on level ground, chock wheels, lift and support on jackstands or use a lift.
- Ensure you have the correct adapter fitting for the transmission test port. If you don’t know the thread, consult FSM.

2. Warm up transmission
- Start the engine and let it idle until transmission fluid reaches normal operating temperature (ideally ~80–100 °C / 175–210 °F). Use a fluid thermometer at the dipstick or rely on warm-up time and temp gauge if you do not have a thermometer.
- Cycle the shifter through all positions (P-R-N-D-2-1) and back to Park to distribute fluid.

3. Locate the test port
- On most Nissan automatics the pressure test port is on the transmission case near the valve body. It may be a Schrader (small valve core) style fitting or threaded boss with a plug. Consult the FSM picture/diagram.
- Clean area before opening to prevent contamination.

4. Remove the port plug / valve core
- If it’s a Schrader-style valve, you can remove the core (or use an adapter that depresses core). If it’s a threaded plug, remove it carefully and inspect the o-ring/crush washer. Capture any drip with a pan.
- Keep the plug and sealing parts if they’ll be reused, but plan to replace crushed washers or a leaking valve core.

5. Install adapter and gauge
- Attach the correct adapter to the test port — use the adapter designed for that port or a proper thread-matched fitting. Do not use pipe dope on o-ring seats; where metal crush washer is used, replace with new washer.
- Tighten to snug torque per manual (or firm, avoid over-torquing which can strip threads).
- Connect gauge hose to adapter and ensure a tight leak-free connection. Make sure gauge line and hose are clear of moving parts and hot exhaust.

6. Baseline readings (Engine running, Park)
- With the engine idling in Park (engine at normal idle), read the line pressure. Record the reading and fluid temperature.
- If noise or leaks occur, shut down immediately.

7. RPM-based checks
- Increase engine speed to specified RPMs per FSM (commonly 1500–2000 rpm) and record pressure. Use an assistant to control throttle, or a remote tach, but never leave the vehicle unattended at speed while under it.
- Some tests require pressures measured in Neutral and Drive. Follow FSM exactly: pressures in N, P, R, and each gear position (D, 2, 1) are often checked.

8. Kickdown / wide-open-throttle (WOT) pressure
- With the vehicle safely restrained and brake applied, rapidly open throttle (kickdown) to measure the maximum line pressure. This is often done only briefly — do not sustain WOT while gauge attached for long.
- Record the transient/WOT pressure.

9. Other specific tests
- Some manufacturer procedures include checking pressure drop during gear changes or measuring accumulator pressures. Follow FSM for those advanced tests.

10. Interpret results
- Compare recorded pressures vs factory specs. Small deviations are normal; large deviations indicate valve body problems, pump wear (low pressure), stuck pressure regulator or blocked filter/strainer, or a worn pump (low) or valve/solenoid faults.

11. Shutdown & reassembly
- Shut off engine before disconnecting gauge if possible to reduce fluid spray.
- Remove adapter, reinstall original plug or new plug/washer/seal as required and torque to spec.
- Refill or top off transmission fluid to the correct level and temperature after replacing seals. Check for leaks.
- Clean up spilled fluid.

Tool usage details / how the gauge works
- The mechanical gauge converts hydraulic pressure to a dial reading. It’s connected to the transmission pressure circuit by a hose and adapter. The gauge should be mounted where you can read it safely (on a stand or held by an assistant).
- Use adapter that engages the test port without damaging the valve core. For Schrader ports, a dedicated Schrader-to-hose adapter that seals properly is ideal (it engages the valve core and uses the factory sealing surface).
- Never hammer on fittings. Tighten by hand then wrench to specified torque.
- If the test port is a threaded plug (not Schrader), the adapter should have a matching thread and an O-ring; don’t use tape on O-ring seats.

Common pitfalls & how to avoid them
- Wrong adapter/thread damage: Verify port type & threads. Using incorrect fittings can strip threads and require transmission removal to repair.
- Cold fluid: Testing when cold yields misleading pressures. Warm to operating temp.
- Leaks when running: Poorly sealed adapter or damaged valve core can spray hot ATF — use good fitting and protective PPE.
- Leaving gauge connected too long at high RPM/WOT: The gauge and fittings are fine for testing, but prolonged WOT can overheat or entrain air — only short bursts.
- Misreading specs: Different transmissions (even in same car line) have different pressures — use the correct FSM for the transmission model.
- Contamination: Dirt or debris near the port during opening can enter the valve body. Clean the area well before opening.
- Not replacing crush washers/O-rings: Reusing old crushed seals causes leaks.
- Confusing sensor vs mechanical test: Don’t confuse checking an electrical pressure sensor (which requires electrical tests) with a mechanical pressure test.

When replacement parts are required
- Replace valve core (Schrader) if leaking.
- Replace thread plug crush washer / O-ring if disturbed.
- If pressures are low or erratic: suspect worn pump (may require removal and rebuild), clogged strainer/filter (replace filter and fluid), damaged valve body/seals (may need rebuild or solenoid replacement), or linkage throttle/kickdown misadjustment.
- If test fitting damages port threads: you may need a heli-coil or transmission removal for repair — avoid by using correct adapter.

Final notes
- Always get the exact test port location and pressure specifications from the service manual for your vehicle’s transmission. The KA24DE was used with multiple transmissions and pressure specs vary.
- Document all readings, temps and gear positions when you test — that makes diagnosis and parts ordering easier.

No further questions.
rteeqp73

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