I've had my '99 4Runner for about two years now, and it's got about 150,000 miles. I've owned lots of vehicles over the years, and the main culprit for the most expensive repairs has always been a cooling system failure. I have read that 80% of all major engine problems are a result of a cooling system failure. I have flushed the coolant in the 4Runner and added new coolant and some Water Wetter, but I'm thinking about replacing the thermostat with a new one just for the sake of it. Has anyone experienced t-stat failure on any of their Toyotas? Both the 4Runners I've had have been fantastic vehicles as far as durability, and I'd hate to change the t-stat out needlessly, but I also think about the mileage getting up there.

Any thoughts? Thanks!

 

was it not changed with the t-belt and water pump?

 

I've never had a t-stat failure in any of my vehicles, but then I replace them on every second coolant change. T-stats are cheap, and it only takes 5 minutes extra when the rad is already empty. If you're worried about it I would go ahead and replace it.

New thermostat = $10
Peace of mind knowing you won't be stranded at the side of the road = priceless