1990 INFINITI M30

Typical onset: 80,000-150,000 mi

Symptoms: Transmission fluid appears pink or milky (coolant contamination), Harsh shifting or slipping after coolant system service, Transmission failure within days of coolant mixing with ATF, Coolant loss with no external leaks

Fix: The internal transmission cooler in the radiator fails, allowing coolant and ATF to mix. This destroys clutch packs and seals rapidly. Best practice is preventive radiator replacement with an external trans cooler install. If contamination occurs, requires full transmission rebuild or replacement plus radiator and complete fluid flush of both systems. 12-18 labor hours for trans R&R and rebuild.

Estimated cost: $2,800-4,500

Typical onset: 120,000-180,000 mi

Symptoms: White smoke from exhaust on cold start, Coolant consumption with no visible leaks, Oil appears milky or chocolate-colored, Overheating under load or highway speeds, Rough idle and misfires on cold start

Fix: VG30E head gaskets leak externally and internally. Many shops see warped heads on these if overheating occurred. Requires both heads pulled, pressure tested, and resurfaced (usually 0.010-0.015 removed). Timing belt, water pump, all coolant hoses should be done simultaneously. 16-20 labor hours including machining downtime.

Estimated cost: $2,200-3,800

Typical onset: 70,000-120,000 mi

Symptoms: Clunk when shifting from Park to Drive or Reverse, Excessive vibration at idle in gear, Visible sagging of transmission tailshaft, Shifter feels loose or notchy

Fix: Rubber mounts deteriorate and crack, allowing excessive drivetrain movement. Front and rear mounts typically fail together. Requires lift access and transmission support. 2.5-3.5 labor hours for both mounts.

Estimated cost: $350-650

Symptoms: Random misfires (multiple cylinders), Rough idle that moves between cylinders, Check engine light with lean/rich codes, Poor fuel economy and hesitation

Fix: Injector plug seals crack with age, allowing moisture into pins. Causes intermittent connection. Requires individual injector pigtail repair or full harness section replacement. Often misdiagnosed as bad injectors. 3-5 labor hours to properly repair all six connectors with heat-shrink solder joints.

Estimated cost: $400-750

Typical onset: 60,000-100,000 mi

Symptoms: Window drops into door or moves crooked, Grinding or clicking noise when operating window, Window moves slowly or binds halfway, Complete failure to move (motor runs but no movement)

Fix: Plastic rollers on the scissor-style regulator disintegrate. Window can fall into door unexpectedly. Requires door panel removal and regulator replacement. OEM parts NLA; aftermarket quality is hit-or-miss. 2-3 labor hours per door.

Estimated cost: $300-550

Typical onset: 100,000-160,000 mi

Symptoms: No-start condition (cranks but won't fire), Intermittent stalling when hot, Dies after 20-30 minutes of driving, restarts when cool, No tach signal or erratic tach needle

Fix: Optical sensor in distributor fails when heat-soaked. Very common failure mode on VG30E engines. Requires distributor removal and sensor replacement. Nissan part still available but expensive. 1.5-2 labor hours.

Estimated cost: $400-700