Symptoms
Coolant loss with no visible leak, white exhaust after warm-up, overheating, misfires — 4Runners.com members say cylinder 6 is the usual victim.
The fix, step by step
- This is an engine-out-of-the-car level job in all but name: drain fluids, strip the intake and exhaust crossover, remove the timing belt and cams, pull both heads and have them checked flat.
- Fit MLS gaskets (they need a very smooth deck finish), new head bolts or studs, and do the timing belt, water pump and thermostat while it's apart.
- Many owners add an exhaust crossover delete to reduce heat at the back of the engine.
Tools & part numbers
- Full metric socket set
- torque wrench
- cam/crank pulley tools
- LCE MLS head gasket set
- 3VZ OE head bolt set (88–95)
- 3VZ timing belt kit (1988–92)
Where to buy the parts
MLS head gasket set — 3VZLC Engineering ↗Amazon ↗
3VZ OE head bolt set (1988–95)LC Engineering ↗Amazon ↗
Timing belt kit — 3VZ 1988–1992LC Engineering ↗Amazon ↗
Water pump — 3VZ (LCE lists 1989–92; confirm fit on 1988 trucks)LC Engineering ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Toyota 4Runner 1st Gen parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.