1991 DODGE RAM 50

Typical onset: 80,000-150,000 mi

Symptoms: pink or milky transmission fluid, sudden loss of all forward gears, transmission slipping after coolant system work, overheating transmission on hills

Fix: The external cooler lines rust through or the internal radiator cooler fails, allowing coolant and ATF to mix. This contaminates the transmission within days. Requires transmission rebuild (8-12 hours) plus new cooler, lines, and radiator flush. Preventive external cooler addition is 2 hours.

Estimated cost: $1,800-3,200

Typical onset: 100,000-140,000 mi

Symptoms: white smoke from exhaust, coolant loss with no visible leaks, overheating under load, oil cap mayonnaise buildup, rough idle when cold

Fix: The 3.0L Mitsubishi V6 has a known weak head gasket design. Both heads typically need resurfacing, new gaskets, and valve seals while apart. Job takes 14-18 hours. If overheated severely, head warping requires machining or replacement.

Estimated cost: $2,200-3,800

Typical onset: 120,000-180,000 mi

Symptoms: oil puddle centered under bellhousing area, oil drips from transmission mating surface, coolant seeping from block sides near freeze plugs, low oil level without visible top-end leaks

Fix: Rear main seal requires transmission removal (6-8 hours). Freeze plugs corrode through on high-mileage examples, especially in rust-belt trucks. Doing all freeze plugs while engine is out for other work adds 4 hours, otherwise spot replacement is 2-3 hours each depending on location.

Estimated cost: $800-1,400

Typical onset: 140,000-200,000 mi

Symptoms: grinding or whining in neutral that goes away with clutch depressed (input bearing), howling that changes with vehicle speed, not engine RPM (output bearing), vibration through shift lever, harder shifting into first or reverse

Fix: Input shaft bearing failure is more common and requires transmission removal and partial teardown (7-9 hours). Output bearing is less invasive at 5-7 hours. Often found during clutch jobs on high-mileage manuals. If fluid has been neglected, internal damage may warrant full rebuild.

Estimated cost: $900-1,600

Typical onset: 70,000-130,000 mi

Symptoms: hard starting when hot, stalling after short trips in summer heat, loss of power climbing grades, won't restart until engine cools 20-30 minutes, fuel gauge erratic readings

Fix: Fuel filter clogs from tank rust (30 minutes to replace, often neglected). In-tank pump fails from running on low fuel or age. Pump replacement is 3-4 hours including tank drop. Vapor lock from heat-soaked lines near exhaust requires rerouting fuel lines and adding insulation (2 hours).

Estimated cost: $400-900

Symptoms: rocker panels bubbling or perforated, cab corners rusted behind rear wheels, bed floor rust-through near wheel wells, frame surface rust but rarely structural, door bottoms rotting out

Fix: These trucks rust aggressively in salt states. Rockers and cab corners are 6-10 hours bodywork each side. Bed floors can be patched but replacement beds are cheap from salvage. Frame typically stays solid but surface rust makes exhaust and suspension work difficult. Not a mechanical failure but kills resale value and safety inspections.

Estimated cost: $1,200-3,500