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I replaced a '97 Ford 302 with a 351 Windsor, but the thrust bearing failed after only 200 miles. What gives?
A. We have all seen the thrust bearing failures in the Ford 302/5.0L engine applications. Many if not most of them have occurred due to the insufficient depth of the pilot hole for the torque converter in the rear of the crankshaft when used in conjunction with an overdrive transmission, and in particular with the AODE electronic overdrive introduced in the 1994 model year.
EngineDataSource.com explains that the original casting number 2MA crankshaft which ended in 1982 had a pilot hole depth of approximately .560" and the introduction of the c/n 2MAE in 1983 had a depth of approximately .680". However when the electronic overdrive transmissions came online in 1994 there was a dramatic increase in these thrust failure issues so in 1997 (the same year the 351 ended) the pilot hole depth was increased to .760-.810" to allow for even greater expansion of the torque converter.
The 351 Windsor was never used with the electronic overdrive transmission so therefore it didn't need the deep pilot hole. The engine swap itself should not have had anything to do with the thrust failure. If you're going to pursue this interchange in the future make certain that you have the rear of the crankshaft pilot hole depth machined to .810" and the problem will no longer exist.
You also want to verify that the transmission cooler is not clogged and that line pressures both in and out are within specifications as well.