28th Dec 2017, 16:21

Yes, the HT 4100 is one of the worst GM engines ever built, let alone it is THE worst Cadillac engine ever built. If anyone is interested in an Eldorado from this generation, my advice would be to ignore years '82-'85 and focus on trying to acquire years '79-'81.

30th Dec 2017, 03:47

My HT4100 went 129,000 miles before biting the dust. Not bad for a 'junk' motor. All these cars are antiques at this point, so even its 307 powered cousins (Riviera & Toronado) can potentially give loads of problems. I've found the 307 is tuned to be as gutless as can be and does not really perform better than the HT4100. Quality remanufactured HT4100s usually give years of reliable service and get better fuel mileage than 307s.