AMI 370 or MP7

[Straydog954]

Hello everybody I’m looking at some older Macks and wondered which engine was more reliable and would give fewer problems. I’ve read that the AMI 370 is the better of the aset engines. Should I focus on the gray engine or look at the MP7 although it would have the dpf ? Anybody ever owned both ?

[96bulldogpower]

We own both.  I wouldn’t say the AMI was the best of the asets, in my opinion the best aset was the AC, just because it had respectable performance for what it was.  I’m assuming you’re looking at getting some type of a vocational truck and not something OTR based on the engine choices you’re talking about.   The AMI will generally be trouble free and have a lower cost of ownership especially when it comes to repairs, but it’s a slow turd and it can even sometimes be a hazard for how underpowered those engines are.  The MP7 will perform excellent especially if you find one with a 397c engine file. Those engines pull hard for the size engine that they are.   Don’t expect them to pull with the large displacement engines, but you’ll be happy with its performance. The downsides are that parts and repairs will come at a tax. We have more problems with our MP7’s than we do with our older aset trucks.   When an aset goes down, it’s usually a quick repair. When an MP goes down it’s sometimes a wild goose chase to find the problem and then to wait on parts.    
having said all of this, your results will vary, depending on the condition of each truck you find and how well it was maintained by their previous owner.  
if you’re considering an MP, try looking for the rare early 07’ model granite CTP713. The early ones had EPA 04  emissions which only came with egr, no dpf or scr.  We have two of those and it’s the best of both worlds, MP power and efficiency with aset reliability, and the newer style cabs are a plus.