Having attained the 600,000 mile milestone with my vehicle a few months ago and additionally never having opened the engine for any maintenance or repairs (and it still runs great), I figured this finally would be a good time to replace some internal engine gaskets. Furthermore, over the last 50,000 miles, I occasionally noticed a very small pool of coolant sometimes accumulating under the back-side of the engine. After eliminating any heater hoses or freeze-plugs as the source of the leaked coolant, a mechanic friend verified that the rear of the intake manifold was in fact showing signs of leaking (as the intake manifold on this engine maintains a water-jacket for cooling or whatever). So, as I said, I figured 600,000 miles was long enough to wait to open the engine to replace some gaskets.
The photos show some of the carbon build-up internal to the top-side of the engine. What can I say? Often driving the vehicle off-road in the sand when I first purchased it, I nevertheless probably only changed the motor oil a handful of times during the first 100,000 miles – if that often. Regardless, knock on wood (and all), the engine still runs fantastically well and even better than before the gasket change!
Here’s to the next 600,000 miles! :)
Adam Trotter, P.E. (January, 2017)