The 1987 BMW 524td is a rare diesel E28 with the M21 turbodiesel—robust mechanically but plagued by aging transmission coolers, stretched timing chains, and injection pump wear that can strand you if ignored.
Timing Chain Stretch and Guide Rail Failure
Common · high severityTypical onset: 120,000-180,000 mi
Symptoms: rattling on cold start that fades after 30 seconds, rough idle, loss of power, check engine light with timing-related codes
Fix: Replace timing chain, tensioner, guide rails, and upper chain guide. This is front-of-engine work requiring radiator removal and careful timing alignment. 8-12 labor hours depending on shop familiarity with M21.
Estimated cost: $1,800-3,200
Injection Pump Wear and Internal Leakage
Common · high severityTypical onset: 150,000-200,000 mi
Symptoms: hard starting when hot, surging at idle, loss of power under load, excessive black smoke, fuel consumption increase
Fix: Bosch VE pump rebuild or replacement. Most shops send out for rebuild (3-5 day turnaround) or install reman unit. Removal and installation is 4-6 hours, timing must be set precisely with dial indicator.
Estimated cost: $1,500-2,800
Transmission Oil Cooler Line Corrosion and Leaks
Common · medium severityTypical onset: 80,000-140,000 mi
Symptoms: ATF puddles under front of car, pink residue on radiator support, low transmission fluid, slipping or delayed shifts if severe
Fix: Replace steel cooler lines (rust through at bends) and rubber hoses. Often done with transmission mount replacement since access is similar. 2-3 hours labor.
Estimated cost: $400-700
Crankshaft and Main Bearing Wear
Occasional · high severityTypical onset: 200,000+ mi
Symptoms: deep knocking from bottom end, low oil pressure at idle when hot, metallic debris in oil filter, vibration through whole car
Fix: Engine out, full bottom-end rebuild with crank grinding, new bearings, and seal replacement. If crank is scored beyond .030 undersize, sourcing replacement is difficult. 18-25 hours for full rebuild.
Estimated cost: $3,500-6,000
Glow Plug Relay and Controller Failure
Common · medium severitySymptoms: extended cranking in cold weather, white smoke on startup, glow plug light flashing or not illuminating, won't start below 40°F
Fix: Replace glow plug relay (behind left headlight) and test individual glow plugs. Controller module under dash also fails. Relay replacement is 1 hour, plugs add 2-3 hours if seized in head.
Estimated cost: $300-800
Vacuum System Leaks Affecting Turbo and HVAC
Common · low severityTypical onset: 100,000+ mi
Symptoms: loss of heat/AC vent control, turbo wastegate stuck open (no boost), hissing under hood, rough idle
Fix: Replace all vacuum lines (they turn to dust), check valve on brake booster, and turbo wastegate diaphragm. Tedious line-by-line diagnosis. 3-5 hours for comprehensive replacement.
Estimated cost: $400-900
Transmission Mount Collapse
Common · low severityTypical onset: 80,000-150,000 mi
Symptoms: clunk when shifting from Park to Drive, vibration at idle in gear, driveline shudder on acceleration
Fix: Replace transmission mount and center driveshaft bearing while underneath. Simple job with transmission jack. 1.5-2 hours.
Estimated cost: $250-450
Buy one if you find a well-maintained example under 150k miles with recent timing chain service and clean injection pump; otherwise, budget $3-5k for deferred diesel-specific maintenance within the first year.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.