Last Friday, my engine finally overheated—with very little warning, as is often the case. Over the past several weeks, I had noticed the overflow bottle I placed under the expansion tank tube was collecting some coolant, though not a significant amount. Then everything let go. Honestly, I’m surprised it didn’t happen years ago—after six years, plenty of tapping noises, and roughly 40k miles, here we are. Total truck mileage is 192k.
I removed the thermostat ( “extinct” mod), and the engine now runs well at around 150–160°F. However, the cooling system is pressurizing excessively, and there’s a coolant film under the oil filler cap, indicating coolant is getting into the crankcase. Adding to that, I’m getting a misfire code on cylinder #3. Given that it’s an ’04 4.6, my suspicion is a slipped liner and/or cracked block and a head gasket failure. Best-case scenario would be just a head gasket—but I’m not optimistic.
With that said, the path I’d like to pursue is finding a bad Rover with a good engine. I’ve currently found a 1997 P38 parts truck with a 4.6 that’s claimed to be a solid runner. My question is whether a non‑Bosch P38 long block will accept all of my Bosch components for a swap, or if I should specifically be looking for a Bosch-era P38 (’98 and newer, I believe).
Any help from the experts is appreciated.

Best - Dave

 

It can be made to work but not easily. Better to find a bosch/Thor variant. Plenty of bad trucks with good engines in the NE/Midwest where the rust eats them FL seems to get a lot of cheap trucks too. You can contact Doc Heydary for a complete engine, he is on facebook, tell him I sent you. If you have a choice get the oldest block/engine you can. Yes, all your guts will go in to a 4.0 block.