One problem related to coolant leaking has been reported for the 2005 Toyota 4Runner. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2005 Toyota 4Runner based on all problems reported for the 2005 4Runner.
For 3 days the car would start with engine roughness, lasting 15 seconds or so (sometimes with a cloud of smoke from the exhaust). On the 3rd day the check engine light, vsc, and trac lights illuminated. An analysis at an independent repair shop found a computer code of p0306 (engine mis-fire on cylinder 6). A borescope video of the cylinder shows small amounts of coolant entering the cylinder, indicating a head gasket leak. Searching this vehicle online and in this database shows a high number of reports of head gaskets leaking into cylinder 6. I am looking at quotes between $2500-5000 for repairs.