1987 CHEVROLET C30

Typical onset: 100,000-150,000 mi

Symptoms: Oil drips from bell housing area, especially after sitting overnight, Transmission fluid contamination if leak is severe, Clutch slippage on manual trans trucks due to oil saturation

Fix: Requires transmission removal, 8-12 hours labor depending on 2WD vs 4WD. Two-piece rear main seal design is prone to failure. Replace with updated one-piece seal conversion kit if available for your engine. Inspect flywheel/flexplate surface for grooving.

Estimated cost: $800-1,400

Typical onset: 80,000-120,000 mi

Symptoms: Clunking on acceleration or deceleration, Vibration through cab floor at highway speed, Visible sag or cracking in crossmember rubber isolator

Fix: The rubber mount collapses from heavy loads and age. Simple job on 2WD (1.5 hours), more involved on 4WD with transfer case clearance issues (2.5 hours). Inspect crossmember for cracks while you're under there — these trucks see abuse.

Estimated cost: $150-300

Symptoms: Transmission fluid dripping from radiator area or along frame rail, Low transmission fluid level with no visible leak at pan, Transmission overheating, especially when towing

Fix: Steel lines rust through where they attach to radiator or at frame mounting points. Total failure means no transmission cooling and rapid overheating. Replace both lines as a set (don't piece it together), 2-3 hours. Check radiator end tank for pink milkshake — indicates internal cooler failure mixing ATF and coolant, requiring radiator replacement.

Estimated cost: $250-600

Typical onset: 150,000-200,000 mi

Symptoms: Blue smoke on startup that clears after warmup, Excessive oil consumption (1 quart per 500-800 miles), Low compression across multiple cylinders, Poor acceleration and loss of power under load

Fix: The 350 and 454 engines in these trucks were often run hard and not always maintained. Ring wear and cylinder glazing are common. Full engine rebuild with bore and hone, new pistons/rings, bearings, gaskets runs 30-40 hours. Short block replacement is 20-25 hours if cores are available. Many shops recommend swapping to a crate motor instead.

Estimated cost: $3,500-6,500

Typical onset: 120,000-180,000 mi

Symptoms: Hard starting, especially when cold, Rough idle with excessive white smoke, Loss of power and black smoke under acceleration, Fuel in crankcase oil (dilution from internal pump seal failure)

Fix: The Stanadyne DB2 mechanical injection pump wears internally, loses timing, and seals fail. Replacement pump plus timing setup is 6-8 hours. Use genuine or quality reman units — cheap pumps fail quickly. Check glow plug system and fuel supply pump while diagnosing.

Estimated cost: $1,200-2,200

Typical onset: 100,000-140,000 mi

Symptoms: Howling or grinding noise from front axle when in 4WD, Gear oil leaking from pinion seal or axle tubes, Vibration or binding in tight turns (if spider gears are worn)

Fix: The Dana 60 front end sees hard use in work trucks. Bearing wear and pinion seal leaks are typical. Full rebuild with bearings, seals, and gear setup is 8-12 hours. If ring and pinion are worn, add another $400-600 in parts. Check for bent axle tubes from plow work.

Estimated cost: $1,200-2,000

Symptoms: Fuel gauge reads empty or erratically, Rust flakes in fuel filter during changes, Fuel pump failure on EFI-equipped trucks from debris

Fix: Steel tanks rust from inside out, especially if truck sat or was used seasonally. Sender float arms corrode and bind. Tank replacement is 3-4 hours with bed removal or tank straps. If going this far, replace all fuel lines from tank forward — they're 35+ years old. Sender-only replacement is 2 hours but pointless if tank is rusty.

Estimated cost: $400-800