[kats96gtconv]

I need advice on what could cause a loud engine knock in my motor. Here's the story in a shortened version. My 1996 Mustang GT 4.6 liter sohc v8 , 5 speed manual transmission, blew a head gasket,. (among many other problems before that.) So, I got a used motor from a 1998 Mustang GT 4.6 liter sohc v8, automatic transmission. I got the 1998 motor for $500, and was told it had about 78,000 miles on it. So, my friend Jason finished the engine swap day before yesterday and even though the car fired right up, it had a loud knock. So he shut it right off. He told me he tried everything to get it to stop, including "honey oil" whatever that is, but it still knocks. What could cause this? Could he have damaged the motor during the swap? Any ideas? I'm about to give up on this car, I've owned it for over three years now and it's been parked almost the entire time. I can't find a good mechanic and was scammed when I got the car. Anyway thanks for any tips.

[jinsc2006]

This may be no help at all, but i know the engine computers (and probably wiring harness") for these are different. Even the 98 with the manual trans is different from the 98 with auto trans. So you couldnt use the one from the 98 AT in your 96 MT.

[kats96gtconv]

Really? I wondered about that. I'm not sure about the computer. I forgot what Jason told me. All I know is I have an extra computer. So, I think he took off the computer from my old '96 motor for a spare and kept the '98 on that motor. Which like I said came off an auto transmission . Would that be incompatible then with my manual transmission? The wiring harness from my car seemed to match up that's the one he used. I have get ahold of him to clarify...Thanks for your help

[belwyrm]

Yeah, If he can tell him to put the computer off the 96 on it. The computer is very different from the auto to the manual.
The 96 - 98 GT motors are exactly the same, so the only differences you're looking for are in the clutch/flywheel. If all that is correct, then someone probably sold you a bad engine, I'd have to hear the knocking.

[racin366]

Have to agree with belwyrm, it sound like you got sold a bad motor, hard to diagnose the cause of a knock without hearing it, could be crank or rods bearing(s), bad oil pump, or valvetrain problems. I'm assuming Jason installed a pilot bearing in the back of the crank, you have to have one for a manual trans