My wife's 1997 Blazer experienced a loss of power while she was driving at highway speed. She immediately pulled over and shut off the vehicle, and we had it towed in to our mechanic. Evidently, damage had occurred to the bearings (spun main bearing) due to oil being thinned out because of contamination with coolant. Earlier in the month, she had noticed that the vehicle was "using" coolant, but not leaking it or leaving a puddle on the ground, so we took it in for repair. The problem was the intake gasket; it was allowing coolant to leak into the block and contaminate the oil. We thought we had taken care of the problem quickly enough, but the spun bearing showed that not to be the case. Fortunately, my mechanic just happened to have a crate 4.3 engine that he sold us for a reasonable amount.

Lessons learned: if the vehicle is "using" coolant, immediately check and find out what's wrong. Suspect the worst (coolant in engine oil) and get an oil change and repair the leak. Also, I have to say that the recommended 5W30 oil is probably too thin for long term use; I have an 1993 Chevy S-10 Blazer that ran over 300,000 miles on the original engine when I used the 10W30 oil recommended in that year's owner manual. Needless to say, we're running 10W30 full syn in the new engine, and it's going strong.

While crossing over the top of the Sierra Nevada mountains in CA, the engine started knocking. It did not take long to get really loud. I pulled into a gas station and called a two truck, who took us and the car to a GMC dealer in Placerville, about 150 miles from home in San Jose. Diagnosis, bad rod bearing caused by an failed intake manifold gasket that let water get into the oil. One week to rebuild and at least $5500. We had the tow truck take us and the car home. Much easier to deal with from home where we also had another car, did not have to pay hotel bills, or would not have to rent a car to go home and then come back up the hill a week or two later to get the Blazer. The tow was $800. the cost of a new log block plus labor was $6500. And not under warranty which expired at 100K miles.