Got an engine with 90k+ miles put into my coupe. Previous engine had like 168k, but was a beast. Got it back and not only is the pickup lacking and very noticeable but the fan runs all the time. My fan never ran like this with the previous engine. Wtf happened?

btw, mechanic gave a 6 month warranty..but that fan constantly running is loud af. I'm hoping it won't burn itself out every time I drive, which is usually 45+ miles. Is this normal for an engine swap?

Sounds like you either had mods on the previous engine, or the new used engine has problems. It could be something simple, but definitely have it looked it, that's not normal. Sounds like it wasn't installed properly or something was broken during the process maybe. A successful engine swap shouldn't come with any compromises.

Thanks, I wanted to make sure I wasn't over reacting as I was thinking the same about an engine swap...Did not seem normal for the fan to stay on for a 45 mile freeway drive. No mods on the previous engine either, except a grounding wire kit done by Sxexcx.
kinda skeptical about bringing it back to the same guy tbh. If he didn't drive it enough to notice this after the swap and still allowed me to drive off... what's really going on at the shop? Sucks bcs it's my old trustworthy shop with a new owner and mechanic running the show.

Does the engine appear to be running the same temperature?

My first engine ran a little below half way and this one doesn't seem too off from that. If anything it has fluctuated from the middle to a hair above.
It doesn't seem to have hot air pushing out from the grill but the fan is always on so... just strange and wanted to know if any one else's fans stay on high while driving ALL the time. The only time it's off is the first 2-5 minutes of driving.

If your AC is on then the fan should be on high all the time. This includes windshield defrost which engages the AC compressor. The light on the AC head will be on if the compressor is engaged

I've been too iffy about the feeling of the car to run the AC in any way, shape or form so it has been off.
Alongside the fan running constantly there's a light tick that is in rhythm which wasn't there before the swap.
I am still curious if any of our engines have had scenarios of a constantly running fan after a swap, or even from the day they bought it.

The IPDM contains the cooling fan relays. Perhaps one of those relays is defective?
See the EC section in the FSM for your vehicle

"The engine coolant temperature (determined "When the engine coolant temperature
Telcoman